Samdim Design

Antonov AN-24RV

for FS 2004



Version 2.02
June 2005


When the model An-24RV from RFGroup appeared for MS Flight Simulator 2000 it was like a revolution in the add-ons design. Since, many simmers tried to adopt this model for FS2002 but without much success. A new visual model and a new panel were needed. After the release of our An-24B and even in spite of an incorrect dynamics, this plane immediately replaced the old one. It has been followed by two other planes of the same family: short-range transport An-26 and aerial photographer An-30. The next release of An-24RV for FS2004 corrected some bugs in An-24B, supplied a new dynamics and added lots of new features namely a full interior with working virtual cockpit and passenger cabin.

The panel update was a rather complicated deal because there had been almost no aircrafts with the same panel. The aircraft itself has been declined in 43 modifications. Each version could have a slightly different cockpit. With the development of avionics, many gauges have been replaced on the existing panels. That's why it is almost impossible to create "The An-24 Panel". We tried to make a general panel that has the most used and typical avionics and instruments on An-24. This panel is very complete because it includes also instruments used on arctic and military versions.

In Version 2 of An-24RV all patches are included and several other changes were made also:

§          Even more realistic, real turboprop flight dynamics

§          Thrust reverse is replaced by propeller blade locking switch

§          New sound package (still not proper however)

§          Enhanced light effects

§          Complete navigation documentation and Navigator Notepad panel

§          COM radio and SPU switch is adopted to frequency changes with VATSIM and IVAO clients

§          Passenger loader application

The model works in both FS2004 and FS2002. The panel works only in FS2004. There is an older FS2002-compliant version available on the web.


Visual model, exterior and interior, animations


Dimitri Samborski (

Exterior painting and many advices about the cabin disposition and levers functionalities, model testing


Nikolai Samsonov (

Interior painting, VC panel disposition, beta-testing


Maxim Mysin (

The panel itself (created in 3Dmax) and some gauges


Valery Bocharnikov (

Gauges GAU and bitmaps to XML gauges, technical support, testing and consulting


Stepan Gritsevsky and Gabor Hrasko

Flight dynamics


Curl, Alexander Terentyev [Aless], Paul [PI134]. Also thanks to Nick Sharmanzhinov [except], Alexander Timoshin [UNKL], Alexander Zuev [ALZP] and Dmitry Kolesnik [TenderCat]



Based on package from Mike Maarse

Passenger loader





Gabor Hrasko (

Installation program


Dimitri Samborski


Thanks to Serguei Skozhevnikov for his help in the development of the autopilot, to Dmitry Ermakov for the complete An-24 instructions docs

Special thanks to George Sukhykh for blueprints and testing, Vladimir Sokolov and Dmitry Kolesnik for their XML gauges taken as example and to RFGroup - Valentin, D.Prosko and others.

Thanks for virtual airline Special Air Service Hungary active and former members - Zsolt Baumann, István Szántai, György Posztos - for testing, documentations and for all other support.

Recommended RSBN scenery is from Andrei Pryadko.

The Aircraft


The visual model  has some animations only accessible if you have shortcuts bounded to the following actions (it can be configured in the Configuration/Key Assignments menu) :

FS event


Select exit - 1

open the passenger door and deploy the ladder

Select exit - 2

open the cargo doors (front and rear).

Tail hook up/down

open the cabin windows

Wing fold/unfold

enter the maintenance mode - open the gear bays, the engines, the nose and lower the antistatic ground cable

Water rudder up/down

deploy glass cleaners

Extend/Retract Concorde nose & visor fully

deploy landing/taxi lights


The visual model has every possible standard animations as follows.

Exterior model animations



Interior and exterior flaps deployment. Interior flaps have little shields that open when the flaps start to deploy (F5-F8).

Control surfaces


All control surfaces are animated and have animated trims (joystick, num. pad. 1, 7, 0, Enter).

Gears, rotating tires


The tires image becomes blurred at high speed to improve the visual effect. Extension/deployment (G) using13 animated parts per gear. Working suspension. Nose gear direction independent from the rudder (the rudder can be disabled by pressing Ctrl-D)

Landing lights


On An-24 landing lights share the same body with taxi lights. To switch on the taxi lights, switch on navigation. Light beams follow the lamp animation (bounded to gears retraction). Attention: usual keyboard shortcuts (L, Ctrl-L) may not work with the panel. Use the correspondent switches on the panel (bottom-left corner)



The passenger door (Shift-E) is supplied with a folding ladder that deploys when the aircraft is on ground. There are also two cargo doors (Shift-E 2) on the right side of the fuselage. Actually, all the doors are bounded to the same key (passenger door) because of an incompatibility of the cargo doors with the panel.

Cabin windows


open them after the landing to equilibrate the air pressure. In the cockpit, they have also animated handles (bounded to tail hook key).

Gear bay doors, engine coverings and nose


all animated for maintenance mode on ground. There is also a little anti-static cable that descends to the ground (bounded to wing folding).



use each three differently textured parts - for still, slow and fast rotation. They dispose of the automatic feathering - it occurs when an engine stops airborne (F1-F4).

Glass cleaners


they are also visible from the cockpit (bounded to water rudder deploy).


Cockpit animations

Throttle levers


on the central console (F1-F4)



joystick with Z-axis



on the rear side of the central console. The flaps switcher features a security mechanism with a locker (F5-F8).



on the rear side of the central console. Like flaps switcher, features a locker (G).

Parking brakes


at the rear base of the central console and beneath the captain's yoke (Ctrl-.).






big wheels on both sides of the central console - move very slowly (num.pad 1, 7).


Cabin windows and passenger door with ladder are animated like in the exterior model.

All the exterior animations visible from inside the plane are present in the virtual cockpit view.

The visual model uses many materials with different levels of dynamic shine and transparency. The exterior model uses reflective textures with alpha-channel and lighting maps. The interior model uses night-lighting textures for the interior parts. Some of the interior parts use also lighting maps.

The visual model contains special instructions to hide invisible parts (like engines interior when the engines are closed) and thus improve the frame-rate. There is also a shadow model that makes the FS engine calculate the shadow far faster and again improve the frame-rate on ground.

Virtual Cockpit

The plane has a fully functional virtual cockpit with passenger cabin and exterior views. Be sure you have the ActiveCamera plugin to be able to move inside the plane; otherwise you can't enter the passenger cabin.

When you are in the cabin, the disposition is the following:

Depending on configuration and difficulty of flight conditions, the aircraft can be piloted by smaller crew. Actually, only two to three people are needed to fly the plane.

Behind you: the passenger cabin. No first class, no economy class - everybody's equal in the USSR.

Gears and flaps controls are specific. The switches are provided with security lockers. To raise the gears, you must first turn the locker, then initiate the retraction with the switcher, raise the switcher to the initial position and lock it again. The same procedure should be respected when operating the flaps. These procedures are done automatically by animation.

The third throttle lever operates the additional jet engine RU-19. Since a jet engine cannot be placed on a turboprop aircraft (FS limitation), the lever is not operational. In fact, it is rarely used in the real life.

The navigator's panel is situated right behind the captain's place. Press "2" on the numeric keypad to move back (using ActiveCamera) and see the panel. A tip: when you move back, you'll first see a map or an approach plan situated on the navigator's panel. Place here the approach plan of the airport you are going to and you will have the possibility to quickly look at it without loosing control of the aircraft. Just move backward and forward with Active Camera. To place you own picture there, put the picture into the Textures folder and name it  A_MAP.bmp. Like any FS texture, it must be 256x256, 512x512 or 1024x1024 pixels and 8, 16 or 32 bit in depth. Grayscale (8 bits) images would be the best. If the image doesn't show up in the cockpit, check it isn't 24 bits in depth and is of a right dimension.



Flight Instructions

Attention: metric system. 100 kts = 185 km/h. 1000 ft = 328 m. 10 miles = 18.5 km

Regimes for engine AI-24:

Regime (mode)


Take off




0.85 nom.


0.7 nom.


0.6 nom.


0.4 nom.


0.2 nom.




Disengage the parking brake, the slowly advance the power levers until UPRT is around 30%. Once the plane starts moving cut back the power to around UPRT 20-25% for a taxi speed 30 km/h (16 kts).

Take-off and climbing

Flaps to 15° (third position).

Arm the brakes, turn propeller lock ON and raise the throttle briefly to 40%. Then raise to 100% and release the brakes (press ".").  Start to raise the plane at ~200 km/h, take off should be at ~220-250 km/h (depending on the weight). Keep the pitch approximately 8-9°. (max 10 deg.). After take off  retract the gear. Above 250 km/h and minimum 120m above ground altitude (AGL) raise the flaps. After raising the flaps, use trimm and throttle to keep the climbing rate constant and the speed at 300 km/h (162 kts). At about 400m AGL reduce UPRT 65% (nominal), and set pitch for a stable 300 km/h climbing. Climb rate will be as follows:

altitude (m)

climb rate (m/s)












Economic cruising mode is UPRT 52% (0.85 nominal). The best economical flight altitude is about 5000 m (16400 ft).


Altitude (feet)





5 000

16 400





6 000

19 700







Descending mode is UPRT 20-30%. The alarm horn will be on below 38%. If bothers (I guess yes), turn ЗВУК - sound alarms switch OFF on the Engineer's panel. No speed brakes, so pay attention of speed.

Descend by approximately 350-360 km/h (180-185 kts) IAS and 5 to 10 m/s (900 to 1800 ft/min) of descend rate.  Keep 300 km/h (162 kts) on downwind and base legs.

The critical speed for descending is 540 km/h (290 kts) to avoid structure deformation.


Keep speed 300 km/h (162 kts) on pattern. On the downwind leg, extend the gear. On the base leg deploy the flaps to 15° and reduce speed to 250 km/h (130 kts). Before the final approach deploy the landing lights and the flaps to 38°. Keep speed approximately 200-210 km/h (108-110 kts) on the final approach. Before the touchdown reduce UPRT around 12-15%, and after touchdown UPRT 0%. Disengage (turn off) "propeller lock". Propeller blade angle will drop and that will create a rather strong back thrust (and noise). The brakes can be used below speed 150 km/h (81 kts) only.

Critical parameters

Maximal speed on descend: 540 km/h (290 kts)

Maximal speed to deploy the gear: 300 km/h (162 kts)

Maximal speed to deploy the flaps to 15°: 300 km/h (162 kts)

Maximal speed to deploy the flaps to 38°: 250 km/h (135 kts)

Maximal flight altitude:  8 400 m (26 800 ft)

Maximal side-speed of wind: 12 m/c (22 kts)

Take off distance: about 900 m (2950 ft)

Landing distance: about 600 m (2000 ft)

Fuel calculation

(unit: 1 lbs = 0.4536 kg)

Fuel consumption during cruising at altitude 6000 m (FL197): 705 kg/h (1550 lbs/h)

Fuel for taxi to line up and climbing to FL197 and descending from FL197, approach and taxi to full stop:  600 kg (1323 lbs)

Note that climb to FL197 and descend from FL197 takes approximately 200 km.

Example: calculate necessary fuel for distance 750 km at altitude 6000 m and cruising speed 460 km/h GS.

  1. Estimate distance for cruising flight: 750 km - 200 km = 550 km
  2. Estimate duration of cruising at final flight level: 550/460 = 1.2 h
  3. Fuel needed for cruising flight: 705 kg/h * 1.2 h = 846 kg
  4. Total fuel needed for flight: 600 kg + 846 kg = 1446 kg
  5. Take 500 kg of reserve fuel (depends on alternate airport distance)

Grand total: 1446 kg + 500 kg = 1946 kg

The Panel

Antonov An-24 has a complex panel and normally it is piloted by a crew of four or five members. It is impossible to put all their gauges on the same screen. In this panel, we applied the principle of multiple workplaces. Our model can be piloted by just one simmer who must take an appropriate workplace depending on the stage of the flight. Each workplace corresponds roughly to the workplace of a crew member. Some concessions have been made to simplify the use of all these panels by one person but the gauges disposition is generally well respected.

Switching between panels.

Switching between some panels can be done as usually by pressing Shift-1, Shift-2 etc. The others are shown/hidden by clicking special zones (buttons or active icons) with the mouse. Shift key assignments are as follows:

Shift key



Flight Engineer's panel




Overhead panel


SPU panel


Navigator Notepad panel


Joystick configuration service panel

Panel display order can not be easily controlled in FS2004. As both the pilot and the navigator panels are large, they have to be the "bottom" panels if you open other smaller panels, otherwise the smaller ones could not be seen. FS defines panel stacking (order) based on opening sequence of the panels - i.e. the one that was opened first will be at the background. Only first-time opening is relevant. To make life even more difficult, some panels are inter-dependent in our An-24RV. For example, the yoke is not needed to be shown on the navigator panel, so it is closed when the user switches from pilot panel to navigator panel. This provokes sometimes a malfunction: the impossibility to show up some of the panels from the navigator panel.

In the present version we tried to implement an automatic initialization process. Uppon aircraft loading we close pilot panel, open navigator panel, close it, and re-open pilot panel. This makes it sure that these panels will be displayed behind all other smaller panels. This panel switching is fast and invisible, but works quite reliable based on our test.

However if you experience that this initialization is not working correctly for you - i.e. smaller panels appear behind the navigator or pilot panels - perform the following manual steps after aircraft loading:

  1. after the main panel loads, switch to the navigator panel
  2. open and close the following panels : autopilot, overhead (КУРС-МП) and SPU
  3. switch back to the main panel

Pilot's panel

The main panel is situated in the pilot cabin. The majority of the panels can be shown from there.

The autopilot panel is called by clicking on the icon "АП-28Л" (low-right corner)

The weather locator (a big screen at the right) is just a decorative element but it serves to switch to the navigator panel. Click on it to show up the navigator panel. Click on the weather locator in the navigator panel to go back to the main panel.

Click in the middle of the yoke to hide it. Click on its axis to show it up. There is also a button on the yoke that calls the SPU panel. When the yoke is hidden, the SPU panel can be shown by clicking on an icon close to the clock.

Above the weather locator, there is an invisible button to show up the overhead panel where all the radios are situated.

The main panel contains the following gauges:

1.                  Magnetic compass

2.                  Indicator signals. The middle and the right leds indicate a dangerous banking: more than 32° in the nominal flight or more than 15° at takeoff or landing (the speed is lower than 230 km/h). The left led indicates that the autopilot is on.

3.                  Pitch (left) and vertical acceleration (right) indicator (AUASP)

4.                  Combined horizontal speed indicator ( КУС-730/1100К. ). Outer scale shows IAS, inner scale shows TAS in km/h.

5.                  Vertical speed indicator (ВАР-30). Measures in meter/sec. 1m/sec = 180feet/min

6.                  Indicator of dangerous engine vibration. Doesn't work for the moment in FS2004.

7.                  RSBN target signaling lamps

8.                  Markers lamp

9.                  Control lamps for "propeller unlocked" feature

10.              Propeller unlock switch. Unlocking the prop diminish dramatically the thrust after touchdown. It must not be switched off during flight.

11.              Artificial horizon indicator. Switch it on from the flight engineer's panel.

12.              VOR/RSBN/ILS course and glide-slope indicator (КППМ).

13.              Two-channel RSBN/VOR/NDB bearing indicator.

14.              Throttle indicator (УПРТ-2)

15.              Engine indicators ЭМИ-3К. Show the oil temperature and pressure together with the fuel pressure before the injection.

16.              The dangerous altitude panel (РВ-УМ). Signals when the altitude is lower than the chosen one. Set the critical altitude with the tumbler on this panel. Switch the monitoring on. "K" is a check-up position..

17.              Altitude indicator (ВД-10). When the pressure is set, an additional gauge appears for 10 seconds. This gauge can also be shown by simply clicking on the altitude indicator.

18.              Altitude (height) above ground indicator (РВ-УМ). Monitoring should be switched on at the dangerous altitude panel

19.              Fast alignment button of the induction compass (ГИК - 1)

20.              Gyrocompass (ГПК-52), it is also used to set up the course in the Turn mode of the autopilot.

21.              RSBN aircraft bearing and distance indicator (ППДА-П).

22.              Exhausting gas temperature indicators (ИТГ-1), Scale is in x100°C.

23.              DME (measures in km with one decimal) and DME 1-2 selector switch

24.              Pitot heating

25.              Landing/taxi lamps deploy. Turn the switch off to hide/protect the lamps during cruise.

26.              Landing (up) and taxi (down) lights. Middle position is off.

27.              Beacon lights

28.              Navigation lights (red-green-white) and also panel lights

29.              Clock (АЧС-1). Clicking on it will make the arrows disappear for 5 seconds. This is done to make easier reading the chronometer and the total flight time.

30.              Flaps Indicator

31.              Gears indicator.

32.              Rpm indicator.

33.              Fuel level indicator (main and auxiliary tanks). Needles show right and left tanks based on mode switch (see next). Outer scale should be read if needles show total fuel, inner scale is relevant for main or aux tank levels. Scale is in x100 kg. If tanks are full, they hold 2 x 4500 Pounds = 2 x 2000 kg fuel, i.e. if Mode switch is set to "total" (СУММА) needles show 20 on outer scale.

34.              Fuel level indicator mode switch (off, total, main tanks or aux tanks).

35.              Not displayed. These gauges are overlaid by Fuel level indicator and Fuel level indicator mode switches. Fuel consumption indicators (РТМС-1.2-Б1). Measures fuel consumption per engines in x100 kg/h. The counter calculates remaining fuel based on consumption. After refuel set this counter to the amount of fuel on left and right tanks respectively. In this case during flight this counter should show similar value than that of the Fuel level indicator (in total mode). Any difference (most probably level indicator shows less then remaining consumption indicator) suggests that you are loosing fuel somewhere (fuel is not consumed only by the engines).

Panel switches:

A.                 Overhead panel switch (above magnetic compass)

B.                 Navigator panel switch (on the weather radar screen)

C.                 Flight engineer panel switch (left to speed indicator)

D.                 Yoke switch (on the emblem of the yoke)

E.                  SPU switch (on the right horn of the yoke)

F.                  Fuel level indicator - Fuel consumption indicator toggle switch (left of trim wheel)

G.                 Autopilot switch (right of trim wheel)

Flight Engineer's panel

In reality, there is no single flight engineer's panel on An-24. Instead, there are several little panels that we have assembled in one to make it useful. It includes three parts: engine startup (ЗАПУСК ДВИГАТЕЛЕЙ), additional jet engine startup (ЗАПУСК ДВ. "РУ-19" - not implemented) and power switches (АЗС).

Engines start block:

36.              Start engine button

37.              Indicator of APD (starter) system. Actually it is lit during the engines startup.

38.              Left-right engine start selection switch. The middle position is neutral.

39.              Stop engine startup button. Shuts down both engines.

40.              Fuel pump ("ПРТ-24") for the left engine.

41.              Fuel pump ("ПРТ-24") for the right engine.

Block of fuses and switchers. Up position is "on", down position is "off":

42.              АККУМ. - accumulator switch;

43.              ГЕН.1, ГЕН.2 - generator switches for the left and the right engines;

44.              ПТ-1000 - avionics on switch;

45.              АГД-1 - horizon indicator switch;

46.              ГИК-1 - gyro-induction compass switch;

47.              СИГН. ШАССИ - gears and flaps indicators on switch;

48.              РСБН - RSBN navigation system switch;

49.              КУРС-МП - Course indicator on switch;

50.              АП-28Л - autopilot power on switch;

51.              ЗВУК - sound alarms on switch;

52.              Propeller de-ice switch and control lamp.

53.              Structural de-ice switch and control lamp.

H.                 Invisible button for closing the panel.

Engines Startup

The engines startup has been slightly simplified. It is done from the flight engineer's panel. The procedure is the following:

To stop an engine, switch off the corresponding "ПРТ-24" switch;

To stop both engines, press the stop engines button "Прекращение запуска двигателя".

The bottom part of the panel is used to start the additional jet RU-19 in the right engine nacelle. This jet is basically used to boost the takeoff but can also serve as an independent energy source in case one or both main engines fail. It provides a 800 kgs additional thrust. Usually, RU-19 is not used at all. As in FS2002-2004 an aircraft cannot be turboprop and jet at the same time, this engine is not implemented.

Overhead Panel

The overhead panel contains mostly the standard radio-navigation stuff. On the real plane, there are many other systems that cannot be implemented in FS2002-2004, like fire extinction systems. We didn't put unusable gauges on the panel because it is already quite overcrowded.

The overhead panel contains the following gauges:

54.              Transponder

55.              Two duplicated sets of NDB source frequency selectors. Upper pair is АРК1 lower pair is АРК2. One can select between main and standby frequencies by switches.

56.              Two sets of VOR/ILS frequency selectors (VOR1, VOR2). No standby frequencies are available.

57.              NDB signal level indicators

58.              COM1 panel with main switch

59.              NDB and VOR system main switches. VOR switch is the same as the one on the Engineer's panel.

60.              COM2 panel with main switch

61.              Radio-system selector.

I.                    Invisible button to close the panel.

Detailed description of these equipment can be found in the relevant navigation chapter.

Navigator's panel

Depending on the modification, the navigator's panel in An-24 can vary from just a bottle of oxygen to a complex system. We implemented here the most complete one, like those used on arctic and military versions. Detailed description of these equipment can be found in the relevant navigation chapter.

The navigator's panel contains the following gauges:

62.              Two ADF panel. Same as on overhead panel.

63.              ADF signal level indicators. Same as on overhead panel.

64.              NAS-1 panel with main switch, map angle and counter (Y, X, XY) gauges. This sub-panel overlays the RSBN panel.

65.              Gyrocompass ГПК-52 panel with alignment knob, main switch and latitude selector

66.              Gyrocompass (ГПК-52), it is also used to set up the course in the Turn mode of the autopilot (same as on pilot's panel).

67.              NAS-1 Lateral Deviation and Automatic Control gauge

68.              RSBN aircraft bearing and distance indicator (ППДА-Ш). Higher resolution (small needle) than that of the pilot's one.

69.              Radio compass source selector switches.

70.              Two-channel ADF/VOR indicator with correction ring

71.              ADF system switches (same as on overhead panel)

72.              RSBN target indicator lamps

73.              RSBN azimuth and distance signal indicators

74.              Clock АЧС-1.

75.              NAS-1 DISS (Doppler radar) Slip Angle and Ground Speed indicator

76.              Gyro-induction compass ( ГИК-1) fast alignment button

77.              DME indicator and selector switch.

The following equipment are identical to the corresponding ones at the pilot's panel and in fact shows the co-pilot panel as seen from the Navigator seat:

78.              RSBN target indicator lamps

79.              Artificial horizon indicator

80.              VOR/RSBN/ILS course and glide-slope indicator (КППМ).

81.              Speed (IAS and TAS) indicator

82.              Throttle indicator (УПРТ-2)

83.              Altitude indicator (ВД-10)

84.              Vertical speed indicator (ВАР-30)

85.              Pitot heating

86.              Landing/taxi lamps deploy

87.              Landing and taxi lights

J.                   Active icons for opening/closing the following panels: autopilot, overhead (КУРС-МП) panel, SPU, GIK-GPK gyro alignment (ГИК/ГПК), RSBN (will overlay with NAS), NAS.

K.                Active icon to switch back to the Pilot's panel.

NAS and RSBN panels are described in details in the relevant Navigation chapter.

Navigation and communication systems

The following chapters describe the An-24RV navigation and communication systems. The RV variant of AN-24 planes were designed to perform special military and arctic operations. These aircrafts are equipped with two enhanced RNAV systems: the NAS-1 and the RSBN-2 systems. These systems are quite independent from each other and are not highly integrated to the autopilot either. On some other Russian aircrafts (for example the Tu-154) these and other systems form a complex navigation system, making it very effective, but really difficult to understand. The relatively simple NAS-1 and RSBN-2 systems makes AN24-RV an ideal airplane to understand these systems in full depth.

Equipment discussed in the following chapters include:

The next chapters starts from basic navigation principles and advances toward enhanced equipment and tools. The RSBN-2 radio-navigation system can only be used over the territory of the former Soviet union (if appropriate RSBN scenery is installed), but the inertial NAS-1 system can be used anywhere on the Northern Hemisphere (limitation is due to gyroscope correction mechanism).

Directions and courses

Magnetic versus true directions

If we try to define our course we run into the problem whether to use magnetic or true directions. In fact in most of the situations with standard planes in FS we use magnetic directions. Runways are named by their magnetic direction, though it generally does not make a big difference, as the last digit is left out from the name anyhow, thus the small difference between magnetic and true heading is not obvious. In Russia, in Northern Europe and in Canada however this difference is quite important.

The magnetic coordinate system has some drawback in some situations:

Because of all of these issues you will find true coordinates rather important in navigation of Russian aircrafts. They went so far that they even worked out a navigation method without using the magnetic compass at all. We will see that later.

Compasses and gyroscopes

A compass is an equipment that could show you the direction to a certain point even if you move from one place to the other. An obvious example is the magnetic compass that points to the magnetic North Pole of  the Earth. Another good example is the radio-compass that points to the given radio transmitter. They even put these two equipment together to form a radio-magnetic-compass (or radio-magnetic-indicator RMI): the needle(s) of the RMI points to the radio transmitter(s) while the ring of the equipment turns so that its top is pointing to the magnetic heading of the aircraft.

Gyroscopes on the other hand tend not to follow any movements. That is their duty - to keep their original direction even if the aircraft is moving, turning or bending. Using some methods you can align a gyroscope to a useful direction - to magnetic North, to geographical (true) North or to your course - and it will try to keep that direction later. It is important however that the direction might become meaningless if you fly over longer distances as the gyro might lose its direction relative to you. That is because the gyro keeps its direction relative to the stars (Universe) and not to the Earth.  This could cause the gyro to loose its alignment even while staying on ground. As Earth rotates 1 degree per 4 minutes (360 degrees per day) the gyroscope performs a similar speed precession relative to the Earth (this precession is simulated in FS if you check "gyro drift" in Realism Settings).

Several type of correction mechanisms are used to keep the gyros aligned to the desired direction. However in some cases it is an advantage that the gyro is not totally "corrected". We will see this at the GPK gyroscope that is showing the true or magnetic meridian direction of the take-off airport even if we fly away long distances.

Loxodrome and the Great Circle

If you maintain a specific heading (generally magnetic, but it could be true as well) while flying long distance you will follow a specific course over Earth surface called loxodrome. It is not a strait line at all (and if you fly long enough you will end up at the magnetic North Pole with a spiral). By definition a loxodrome is intersecting each meridians by the same angle. If you want to fly from point P1 to point P2 than it is some dirty calculation to figure out what should be the correct loxodrome and heading, but once it is done, navigation is quite simple: just keep that (magnetic) course and you will end up at point P2.

If you want to fly from P1 to P2 on the shortest route you have to fly on a great circle course (orthodrome). Great circle is a circle defined by the intersection of the surface of the Earth and any plane that passes through the center of the Earth. There are infinite number of great circles on Earth - the Equator and all the meridians are specific examples for that. For us a single great circle is interesting; the one that goes through P1 and P2 points. Calculation of this great circle is rather simple using spherical trigonometry, but navigating is much more difficult. Great circles are intersecting the meridians by variable angles because of meridian convergence. You have to start with a specific course angle from P1, but along the course you have to change heading angle to remain on the great circle. This is practically impossible to do using a magnetic compass.

Great Circle is the shortest route on a globe. Earth is not a perfect globe. Its form is called geoid and on a geoid the shortest route is called geodesic and it is rather difficult to calculate. Anyhow the difference between the geodesic and the great circle is negligible in aviation.

Flying on the Great Circle (orthodrome)

Flying on an orthodrome instead of a loxodrome has several advantages. The generally known reason is that this is the shortest distance between any two points on Earth. In fact this difference is quite small on middle latitudes and shorter distances: on a 600 km flight the saving will be not more than 10 km. On longer distances the saving is increasing but as the maximal range of our AN-24 is around 2000 km the saving is not significant. On higher altitudes and near to the magnetic pole however the saving is quite important.

The other advantage of the orthodrome relates to radio transmitter radials. These radials are in fact orthodromes. If you would like to precisely follow a radial either towards or from a beacon you have to fly on a great circle. As the range of such transmitters are rarely larger than 300-400 km, the difference between a loxodrome and an orthodrome is not big, but in precision flights it could be important. On the other hand if you use a magnetic compass to follow a transmitter course, you might find that you have to adjust your magnetic heading time by time to maintain the needle of the VOR track indicator (HIS, KPPM) in the middle. This is especially important in AN-24 where the autopilot will not follow a VOR track automatically.

Orthodrome (great circle) flights are supported by special gyroscopes. At point P1 you spin the gyro, align it for example towards true North and you follow the calculated start angle on the route. The gyro will not point to North any more on the route (it will point to parallel of the meridian at P1 still), but it does not matter. Just follow that initial course angle and you will arrive to P2.

Figure 1 - On the Great Circle the course angle (true or magnetic) is changing continuously
as you proceed from P1 to P2. You should maintain the angle relative to the meridian at P1.
That is where a gyroscope will be handy.

If from point P2 you would like to continue to point P3 on a great circle, you have to make some more trigonometry to calculate the start angle from point P2. This angle is to be measured from the meridian at P2. The problem is that our gyro is still aligned to the meridian in point P1 and it is obviously not aligned with the meridian in point P2 as the meridians are converging to the pole (that is why our start  and arrival angles differ).

Figure 2 - The course angle from waypoint P2 to P3 should be adjusted
by the Fork angle that is a result of the convergence of the meridians.

We have two options now:

Orthodromic Course Angle 2 = Course Angle 2 + Fork 2

In Russian terminology (see explanation later):

OZIPU2 = ZIPU2 + Δa2

We can continue with either methods when we reach point P3. Russian navigation use(d) this technics so much that they sometimes do not use magnetic compass at all. Before take-off they align the aircraft along the runway precisely. The magnetic direction and the declination of the runway is documented, so the true heading of the aircraft can be calculated easily. They align the gyro to the true North based on this and they follow the method described above along the route. Near to the destination airport they make a similar calculation based on the magnetic direction and declination of the runway, so keeping in mind the calculated cumulative fork they are able to define the final turn.

In the example above we aligned our gyro to true North (after calculating it form magnetic direction and from magnetic declination of the runway), thus we used true courses all along the route. If you prefer you might align the gyro to magnetic North at the take-off runway and use magnetic courses on the route. In this case however you should modify the above algorithm:

It is basically your decision whether to use magnetic or true courses. True courses have the advantage that they are calculated directly from the equations and they are independent of the spatial and temporal changes of magnetic declination. Magnetic courses have the advantage that they are widely used in charts, maps for example in SIDs and STARs and in ATC conversations.

VORs are "advertising" magnetic courses (bearing), but their Russian counterparts - RSBN beacons - use true courses. The complete RSBN-2 equipment on AN-24 is built around true directions, thus it could be quite ambiguous to align our gyro and define our courses relative to magnetic pole when we use RSBN. NAS-1 navigation system however is independent of external systems, thus it can be used with any reference directions.

Russian terminology

If you are challenged enough to read Russian documents you will realize that they are generally very precise in terminology. It is rather difficult to translate the terms to English. In fact they are not frequently using the terms but abbreviations instead. Hereby I summarize the most important terms.

The most annoying thing is the different use of the term "course". In English it means the track on which the aircraft is moving. May also mean the angle ("course angle") - the track's angle to the reference direction - true or magnetic North. Thus we can speak about true and magnetic course. In Russian the term "курс" (kurs) means "the angle between the reference direction and the extended longitudinal axis of the aircraft" - i.e. "heading"!

The Russian equivalent of "course" is "путевой угол" (track angle). The difference (angle) between the course and heading is called "slip angle" ("угол сноса") and is generally caused by cross-wind:

Course = Heading + Slip

"Курс" (heading) is either true ("Истинный курс, ИК") or magnetic ("Магнитный курс, МК"). "Путевой угол" (course) is also either true ("истинный путевой угол, ИПУ") or magnetic ("магнитный путевой угол, МПУ"). If it is the planned (required) course than they call it "заданный истинный путевой угол, ЗИПУ" or "заданный магнитный путевой угол, ЗМПУ" depending on the reference direction. And finally if the course is measured relative to a reference meridian and not directly to the actual meridian, then it is called as "ортодромический заданный истинный путевой угол, ОЗИПУ" or "ортодромический заданный магнитный путевой угол, ОЗМПУ" respectively:

ОЗИПУ = ЗИПУ + вилка

The course referred frequently within this document - ZPU is the "planned course" ("заданный путевой угол, ЗПУ"). However when used in conjunction with the RSBN navigation it has a special meaning: It is the course (angle) measured at the RSBN radio station between the true meridian and the line going through the RSBN station parallel with the "planned course" (see details later).

The Earth magnetic field in FS9

The Earth magnetic field can be described by the magnetic North vectors at each point on the Earth surface. In practice magnetic declination used to be defined for each location. FS stores global magnetic declination database in the \Scenery\BASE\Scenery\magdec.bgl file. The database might be quite old (some says it is from the early 80th, I did not check), but if you are not using other external data, this will not cause any problem. FS stores a single declination value for each 1 x 1 degree area. When defining declination for a given location FS makes two dimensional linear interpolation. FS Navigator on the other hand rounds the location coordinates (latitude and longitude as well) to the nearest integer and uses a single value from the database thus in areas where declination changes fast (near to the magnetic poles) it gives practically useless magnetic courses. Use FS Flight Planner this case, or the Route Planner provided with this document.

Sceneries define magnetic declination to several individual objects as to airports, VORs, NDBs, ISEC points etc. These might or might not match to the global declination "below" them. However during navigation FS uses the global declination table and adjusts aircraft equipment based on that only. It means that magnetic compass or gyro-induction compass will show magnetic North based on this table regardless of individual scenery elements' declination values. The local (scenery-based) value has any role only in "aligning" the scenery elements (runways, ILS beams etc.). Thus you have to care about it only when turning to final generally. Anyhow we hope that scenery objects define similar declination values than that of the global database ones.

Magnetic compass

I think I do not have to introduce the magnetic compass. It looks like a sphere on AN24-RV and you can find it at the pilot panel at the right of the cockpit window. It is quite hard to read and you will see that we will practically never use it.

The magnetic compass has a lot of problems on an airplane. It reacts slowly, then it takes a long time to stabilize in the new direction. In steep turns it simply hangs up. Even in a bit more moderate turn it is rather impossible to judge when to come out off the turn based on the magnetic compass.

So I think it is not worth speaking about it any longer…




The GIK gyro-induction compass

Gyro-induction compass (Гиро-индукционный компас, ГИК) is replacing the traditional magnetic compass in most situations. It consists of a gyroscope that can be aligned to the magnetic North using a specific device component (ИД - индукционный датчик). This component "scans" Earth's magnetic lines of forces using a rotating induction coil. This way the gyro is kept aligned to the magnetic lines of forces thus to the magnetic North Pole. When switching on GIK you can speed up automatic alignment by pressing and holding the "fast align GIK" button (right to the compass gauge): alignment should happen within 20 seconds. During steep turns and larger accelerations GIK might loose alignment; you might again align GIK with the "fast align GIK" button. During normal flight operations the induction circuit will make necessary corrections continuously and automatically.

Using this gyroscope to keep track of magnetic directions has some advantages over the conventional magnetic compass. The gyro is much less sensitive for steep turns and accelerations and it reacts faster.

Figure 3 - The gauge of the GIK compass with two NDB/VOR needles (and with the corresponding selector switches) and with the "fast align GIK" button

There are several gauges linked to the GIK gyroscope, most important one is being the one shown above from the navigator panel. Its inner scale is rotating and the number at the top (signed with small arrow) shows the magnetic heading of the aircraft. On the outer scale you can set a correction value for the correction circuit (коррекционный механизм - КМ) between ±50°. The two needles of this gauge can be connected to either NDB or VOR stations by the switches above (up = NDB, down = VOR). The whole gauge can be seen as a sophisticated RMI (radio-magnetic indicator or compass).

Figure 4 - The KPPM (left) and the RMI (right) gauges
on the pilot panel are both using the GIK defined magnetic heading

The KPPM gauge on both the pilot's and the navigator's panel shows the heading defined by the GIK with a funny needle (circle with arrow). KPPM gauge receives corrected heading value from GIK. If you set magnetic declination as correction value on GIK, KPPM will show true heading instead of magnetic one. On the outer scale of KPPM you can set desired course or heading.

The pilot's RMI indicator shows the magnetic heading provided by the GIK. This heading is not affected by the correction ring setting (at least not in the simulated plane), so it always shows the magnetic heading! The outer scale is fixed and shows bearings relative to the aircraft's longitudinal axis. The two needles can show different transmitter combinations based on the bottom two switches. The left switch (yellow needle) is 3-stage (RSBN/NDB1/VOR1) the right switch (white double-line needle) is 2-stage (NDB2/VOR2). It is basically the same as the navigator's RMI with the addition that is can also show RSBN bearing. In many airplanes there is a dual ADF (NDB) indicator at the pilot only. This RMI is built in to AN-26 planes mainly.

The autopilot (introduced separately) can also use the signals of the GIK to maintain the current magnetic heading (loxodrome course flying).

The GPK gyro-compass

GPK (Гирополукомпас, ГПК-52) serves course information for several navigation subsystems. It is a separate gyroscope designed especially to support flying on the Great Circle (orthodrome). This compass is designed to correct precession and it keeps its direction relative to the meridian (latitude line) of the point where alignment was made for a longer period. Its configuration gauges can be found on the navigator's panel.

Figure 5 - GPK configuration panel. From left to right: big "GIK-GPK align switch",
"power switch", "latitude selector" and the "GPK indicator".

To perfectly correct precession caused by Earth rotation the actual geographical latitude (or an "average" latitude for a route segment) should be set on the "Latitude Selector". Latitude can be modified during the flight - it should be if latitude is changing several degrees. The power switch also has to be turned on. At this point the gyro is spinning and is maintaining its axis relative to the actual meridian (later called as reference meridian), but it is not yet aligned to any specific meaningful direction.

As soon as you turn the power switch on the small green airplane on the "GPK indicator" rotates to an angle which is quite arbitrary. On the picture above the gyro was initiated showing the aircraft heading as 115 degrees. It means nothing as we had not defined a reference direction yet - we have to set a meaningful value. You can turn the airplane figure to any meaningful degree using the big knob (ЗАДАТЧИК КУРСА) at the left. You can change alignment by 0,25 or by 2 degrees in any directions depending on which area you click on the knob. In most cases you align GPK to the magnetic heading provided by the GIK gyro (thus the two gyros are aligned to each other), or to the true heading which is calculated using the magnetic heading and the magnetic declination of the current location. To make a more precise alignment you can invoke the GIK/GPK alignment panel clicking on the "ГИК/ГПК" (GIK/GPK) hot spot on the navigator panel.

Figure 6 - GPK-GIK gyro alignments. GIK is already aligned with the magnetic compass and current magnetic heading of the plane is 90 degrees as pointed by the red arrow.
A: Full alignment. GPK will provide course (OZMPU) relative to the magnetic reference meridian.
B: GPK is aligned with a magnetic declination of 4 degrees. It will provide course (OZIPU) relative to the true reference meridian.
C: GPK 0 degree is set to the current magnetic course,  here to 90 degrees (rarely used).

As you will fly over long distances you will notice that the two gyros (GIK and GPK) will lose their initial alignment. It has several reasons: it is mostly because the moving airplane's relative position to the magnetic pole (pointed by GIK) and to the initial meridian (GPK) will become different. You can re-align GPK to GIK or to the true North again, but in certain cases it is not necessary or even forbidden otherwise you lose your track. It all depends on what is actually important to you. We will see it later.

The pilot has a same "GPK indicator" gauge as the navigator has. The green airplane's nose always shows the heading of the real aircraft based on the GPK. The whole "GPK indicator" ring can be rotated using the knob on the left-bottom of the gauge. It is used to execute automatic turns to the predefined GPK-based heading by the autopilot. The degree on the top (pointed by a white small rectangle) shows the planned direction after the turn. Autopilot will perform the turn if you select the Turn mode on it (see later).

The simulated GPK gyroscope can not be used on the Southern hemisphere because Southern latitudes can not be set on the GPK panel. In some other aircrafts there is a North/South switch attached to the Latitude Selector, but that is missing in this version of An24 and entered value is interpreted as Northern latitude. If wrong latitude is set, precession correction will not work correctly and GPK gyro will lose its alignment to the reference meridian rather fast (test it in FS!). The picture on the right shows a simulated Il-18 aircraft's gyroscope panel; that consists of a North/South (СЕВЕРН./ЮЖН.) switch above the Latitude Selector (the other switch is the main-supplementary gyro selector).

Connection of the gyros to other equipment

At this point it is interesting to compare AN24 gyroscope connections to that of other aircrafts. One would see that in principle there is no real difference. In AN24 the systems are more separated thus didactically better to understand the concepts behind.

AN24-RV gyroscope connections

The two gyroscopes are connected to other aircraft equipment in a rather straightforward way. This is described in the picture below. It is important to understand that GPK Indicator always shows direction based on the GPK gyro alignment. The other RMI type of equipment show magnetic directions based on the GIK gyro. The Dual ADF Indicator and the RSBN Bearing-Distance Indicator (not shown on the picture) are not connected to either gyros, they show radiomagnetic bearing relative to the aircraft horizontal axes or to the meridian at the (RSBN) locator station.

Figure 7 - Connection of GPK and GIK gyroscopes to various input and output devices. Pilot's RMI is not getting input through the correction mechanism (KM) - at least not in the FS model.

Gyroscope connections on other aircrafts (not An-24/26)

On some other aircrafts there are no separate GIK and GPK gyros. There is a GPK gyro only that has several work modes. On some aircrafts the gyros are duplicated (Tu-154, Il-18) for reliability, accuracy and comfort. You can select via a switch whether the main or the supplementary gyro should provide course information to the different equipment. The gyros can work in different modes:

GPK              This is the "native" mode of the gyroscope without additional correction mechanisms. Though these gyros are correcting several disturbing effects (for example precession) on their own, they will slowly lose alignment to the desired orthodromic direction due to minor configuration and construction errors.

MK               Magnetic correction mode. In this mode the gyro is continuously adjusted by the magnetic induction circuit ИД-2М (exactly like in case of GIK gyro on AN) using also the correction value we set on КМ-4 for declination and for other deviations. The gyro acts as a magnetic compass, but it is most reliable/robust than a traditional compass. This mode is used to follow loxodromic courses or during take-offs and landings, when magnetic directions are used and where there is no difference between orthodromic and loxodromic courses due to short distances.

AK                 Astronomical correction. In this mode the gyro is continuously adjusted by a component like ДАК-ДБ-5 providing true orthodromic course ( I have no information about how this component is exactly working). In FS in most cases this is simply implemented as a very accurate source for true direction. It is generally even independent of cloud coverage and other blocking factors, so it is not very realistic (it is too good).

In most of the cases modes for the individual gyros (main gyro and supplementary gyro) can not be set totally independently. If the active gyro (that provides course info to the other equipment) is in GPK or in AK mode, the other one is in MK mode. If it is in MK mode, the other one is in GPK mode.

The gyro also used to be adjusted either manually or automatically based on external radio-station references. Generally the radio references have the priority and when they are not available the system will use AK or MK mode whichever is selected. Generally a warning will appear that radio-synchronization is not available and the inertial correction systems are working. In deep turns or during greater accelerations AK and MK correction is temporarily disconnected from the gyro by ВК-53РВ.

The Autopilot

The autopilot (AP) of AN24-RV differs from what we could find in the Western aircrafts. In fact there is a relatively small overlap between the functionalities of the two types. Hereby I summarize briefly what this AP is capable for and what not:

It CAN …

It can NOT…

maintain current altitude

climb or descend to a specified altitude

maintain the current pitch

maintain a predefined vario

turn with defined banking

maintain a predefined speed (A/T)

maintain heading based on GIK or GPK gyros

follow a VOR or ILS radial (NAV)

turn to a predefined heading based on GPK

follow an ILS glide slope (APR)


The great minus is lack of auto-thrust and radial tracking. Both exist in some other Russian aircrafts.

There is an extra feature not listed here: the Automatic Control system of the NAS-1 system. It rather much differ from the general logic of AN24-RV autopilot and is generally not built in to AN-24 planes. Based on my best knowledge it is built in some specific purposed AN24-RVs. NAS-1 is an important component of some other Russian aircraft's AP system and it is working correctly in the FS AN24-RV. Its functions are discussed separately.

Figure 8 - The autopilot panel in AN24-RV

The AP can be invoked by the Shift-2 combination or by clicking on the "АП-28Л" hotspots on either the pilot's or the navigator's panel. The brief description of the components are as below:






Power switch to turn on AP



Yellow lamp indicating that AP is in standby mode. It will go on some seconds after you turn AP power switch on.


Engage AP

Button to engage AP once it is in standby mode. AP can be engaged in any conditions provided the altitude is greater than 300m, the pitch is between -20° and 20° and the bank is between -30° and 30°.



Green lamp indicating that AP is engaged and is controlling the plane.


Turn L-R

Coordinated turn to Left or to Right by the define banking. Click on the middle of the control to bring the plane back to straight flight fast. Scale is by 5 degrees up to 30 degrees banking.


Altitude corrector

Button on the right turns altitude corrector KB-11 on.
Green control lamp turns on and AP will maintain the present altitude. Vario must not be bigger than 1.5 m/sec when activating this feature. This mode is not to bring the plane to horizontal flight, but to maintain the present altitude after you had already brought the plane into level flight.


Bring to level flight

Button bringing the plane to horizontal flight. This is not implemented, even the button is missing. In FS you can use КВ to perform the same action - though it is forbidden to do it in real plane.


Descend - Climb

Push and hold switch up to decrease pitch.

Push and hold switch down to increase pitch.


GPK - GMK - Turn

3-stage mode selector switch:

GPK: maintain current heading using GPK gyro

GMK: maintain current heading using GIK gyro

Turn: Turn to heading defined on the "GPK Indicator"



Turn on the switch to let AP using the trim automatically.

Turn off to manage the trim manually



Turn on the switch to let AP manage pitch

Turn of to manage pitch manually


From you

Lamp signs force on yoke from you is managed by the servo


Towards you

Lamp signs force on yoke towards you is managed by the servo


Regarding RNAV the mode selector switch is the most important component of AP:

GPK mode             The AP will maintain the actual heading (not course) based on the GPK gyro. The aircraft will fly on a great circle if there is no drift (wind).

GMK mode            The AP will maintain the actual heading (not course) based on the GIK gyro. The aircraft will fly on a loxodrome if there is no drift (wind).

Turn mode              The AP will perform a coordinated turn to the direction set on the GPK Indicator gauge. The airplane will turn until the small green aircraft symbol on the gauge will be vertical and point to the heading shown on the top. Do not forget about wind drift when you define the target heading on the GPK Indicator. After completing the turn switch the mode to either GPK or GMK mode to maintain the heading! If you leave the mode as Turn, AP will turn back the plane to the defined heading after you finish a manual or AP-based (РАЗВОРОТ Л-П) turn. This is generally not what you want and could be rather unexpected. You will probably do not understand why the plane is turning back always.

"Turn mode" can be effectively used when you are getting vectors during a STAR (approach) procedure. As soon as you receive the instructions from the ATC, you set the required heading on the GPK Indicator and switch on Turn mode. The plane will perform turning to the new direction, you do not have to bother to come out from the turn manually. Of course in this case GPK should be aligned with GIK to work with magnetic direction as SID/STAR procedures and ATC are defining magnetic courses. In case of frequent vector changes you might leave AP in Turn mode so that you just have to modify direction on the GPK Indicator and the plane starts turning immediately while you can read back the instruction to the ATC.

There is a separate Service Panel where one might further configure the AP. The full description of that panel is out of the scope of this document, we mention three parameters only:

Совм.управл         Combined control button. This is assigned to the 1st button (brake) of the (1st) joystick by default. Pressing and holding the brake button of the joystick while the AP is engaged will temporarily disengage AP (green button goes off, yellow button goes on signing standby mode). You can control the plane by the joystick and as soon as you release the brake button, AP is taking back control maintaining the new pitch.

Быстр. Откл          Fast disengage button. This is not assigned to any joystick buttons by default. If you would like to disengage AP (go to standby mode) you have to either press and hold brake button (but this only effective while you keep brake button pressed), or you should turn off and on the AP main switch. Define a free button of the joystick to this function here and then if you press this button, AP will go to standby mode. You just press the button, you do not have to keep it hold.

Вкл.АП                  Engage button. This is not assigned to any joystick buttons by default. This function is available by clicking on the ВКЛ АП button on the AP panel. If you define a free joystick button for this function here, it will be available from the joystick as well.


General navigation and communication systems

General navigation and communication systems include VOR/ILS, NDB (АРК) systems, transponder and COM radios. These equipment are working the same way as in Western planes (and in default planes of FS) and they are not described in details.

Radio source selection

The radio source selector on the Course-MP panel is used to select the signal source (VOR1, VOR2 or RSBN) for the gauges connected to the course system - KPPM and DME. The four red lamps indicate missing (!) horizontal (Г1, Г2) and vertical (К1, К2) direction beam of VOR1 and VOR2 respectively. Vertical beam signal will be received in case of ILS beacons only.

KPPM gauges of the pilot and the navigator can show signals from different sources. The combination can be set by selecting one of the five options on the selector switch:


KPPM at the pilot

KPPM at the navigator

















This is not working correctly on my installation. Navigator's KPPM shows always the same as the pilot's one.

The NDB (АРК) system

This system is a standard NDB (non-directional beacon) system, sometimes called as ADF (automatic direction finder). Frequencies can be set on the Course-MP panel.

Figure 9 - Dual ADF (NDB) indicator,
ADF/VOR/RSBN RMI for the pilot,  ADF/VOR RMI for the navigator

The dual ADF indicator is displaying NDB beacon bearings relative to the aircraft's horizontal axis. The more complex RMI indicators are connected to the GIK gyro and shows the navaid bearings relative to magnetic North, while the top of the rotating ring shows actual magnetic heading of the aircraft. On the outer ring of the navigator's RMI you can set a correction value for the GIK based direction and it effects how courses appear on other equipment. However the RMI on the pilot's panel is receiving non-corrected raw direction data from GIK.

The Course-MP (VOR) system

This system is a standard VOR/ILS navigation system developed originally for navigation outside the Sovietunion. Nowadays VOR and ILS stations are widely used in the area of former Sovietunion (CIS). Frequencies and bearings (radials) can be set on the Course-MP panel.

Be careful - unlike in the real plane - in the simulated AN-24RV you can not select TO and FROM (inbound/outbound) directions. It is assuming always the logical one - do not think in inbound or outbound only in direction. It will rarely cause confusion. In case of ILS you do not have to select course at all. The course system here always assumes TO mode and we can not use the ILS easily to maintain runway heading for departure as we can not select back-course. You might however use the ILS at the other end of the runway if back-course for that ILS in the scenery is enabled.

KPPM is a standard horizontal navigation and landing system displaying position of the aircraft relative to the vertical (ILS only) and horizontal direction beams of the VOR, ILS or RSBN system. Blinkers are closing upon receiving horizontal and vertical direction signals.

ADF/VOR RMI for the navigator, DME indicator

DME indicator shows distance of the DME or VORDME station in kilometers with one decimal digit (100m). Source can be selected by the switch at the top.

RMI indicators for the navigator and for the pilot can show VOR station bearings. The bearing is always magnetic.

Course-MP system is connected to the GIK gyroscope and is using magnetic directions always.

Listening the Morse sign of the radio-stations

AN24-RV is not equipped with a Morse decoder thus one should listen to the raw received Morse signals to check whether the correct radio-station was tuned or not. Selecting the correct source is quite difficult and involves several gauges.

Figure 11 - SPU panel and the VOR/NDB selector

On the SPU aircraft intercom (СПУ - самолетное переговорное устройство) panel you should select RSBN, NDB1/VOR1 or NDB2/VOR2. You select between NDB and VOR on the VOR/NDB selector switches at the navigator panel above the large RMI indicator. These switches select input for the RMI indicator as well. You also have to select radio-source.

The following table summarizes the settings of the various switches for listening Morse signal of VOR1, VOR2, NDB1, NDB2 or RSBN stations:


SPU setting

VOR/NDB selector

Radio source selector

NDB systems power***




1 or СОВМ*





СОВМ or 2






NDB2 should be off***





NDB1 should be off***




РСБН or РСБН/СП-50**



There are some strange settings that are due to FS limitations, but also there could be some bugs here as well:

*          In fact you can set 2 on the radio-source selector as well

**        In fact you can set 1 on the radio-source selector as well

***      If both NDB (АРК2) systems are switched on you will not hear the Morse code even if all other switches are set correctly.

Morse codes are as follows:










































































Short-range Radio-navigation System (RSBN-2)


Short-range radio-navigation system (РСБН - радиотехническая система ближней

навигации) is a key component of RNAV navigation on AN-24 and on other Russian aircrafts. It is similar to the VOR system, but is expanded to support flights not directly going to or coming from a radio-station, but to any points within the range of the system. Though it is called "short-range" it is in fact longer range than VOR navigation. Typical RSBN beacons has a range larger than 400 km. As this is also a short-wave navigation system it's effective range depends on the altitude of the airplane:


Altitude of aircraft (m)


1 000

3 000

5 000

7 000

9 000

11 000

12 000

RSBN range (km)










Accuracy of the RSBN system is said to be slightly better than that of the VOR system. Distance (orbit) is measured by the accuracy of ±200m, azimuth (bearing) is by ±0,25°. Stations are not selected based on frequency directly but based on "channel number" (канал). Channels are assigned to frequencies starting from 116.00 MHz (channel 1) stepping by 0.05 MHz up to channel 40, frequency 117,95 MHz (1:116.00, 2:116.05, 3:116.10, …, 39:117.90, 40:117,95).

RSBN system on the airplane continuously checks the position of the aircraft relative to the beacon. Direction is relative to the RSBN station, i.e. it is measured relative to the true (!) meridian going through the station, so it points from the station to the airplane (or to the target). This is called azimuth and it is not exactly the reverse direction (±180°) of the bearing to the station from the aircraft. The difference is due to meridian convergence and it is equal to the fork discussed in earlier chapter (in smaller distances the difference is negligible) .

Work modes

RSBN is supporting several work modes:

Azimuth TO                (АЗИМУТ НА) The target is on the same RSBN radial we are flying, but its azimuth (direction from the station) is just opposite. It means that the target is right between the aircraft and the radio-station, so we have to fly TOWARDS the station to reach is.

Azimuth FROM         (АЗИМУТ ОТ) The target is on the same RSBN radial we are flying, and its azimuth (direction from the station) is the same. The station is either behind us, or it is ahead of us, but in this case the target is behind the station, so finally we have to fly away FROM the station to reach it.

LEFT orbit                 Supports flying what is called an anticlockwise DME-Arc in Western style navigation. The radio-station is on your LEFT (ЛЕВО) side and you fly at a define distance (orbit - ОРБИТА) from it.

RIGHT orbit              Supports flying what is called an clockwise DME-Arc in Western style navigation. The radio-station is on your RIGHT (ПРАВО) side and you fly at a define distance (orbit) from it.

SRP                            This mode (СРП) makes it possible to fly over a point that is anywhere within the range of the radio-station. The point is defined by it's azimuth and orbit. These data are referred as Target Angle (УГОЛ ЦЕЛИ) and Target Distance (РАССТОЯНИЕ ДО ЦЕЛИ) in this case. The required course (ЗПУ) should be defined also. This mode provides the greatest freedom in flight, but has less accuracy.

Landing                      Not supported in FS simulated AN24-RV. It has to be provided glide-slope assistance beside vertical guidance similar that of ILS. It requires special RSBN station and it is (was) used mainly in military aviation.

Figure 12 - Select mode FROM if your course and azimuth are equal.
If they are opposite to each other, select mode TO. For all other cases select mode SRP.

One has to use special calculations to precisely define the appropriate parameters and mode (the method is described later and a tool is provided separately). We have to pick up the geographical coordinates of the starting waypoint (P1), the target waypoint (P2) and of the RSBN station (PR). You can use either MS Flight Simulator Map/Fight Planner or FS Navigator. We have to calculate the three main parameters first:

Target Angle                (УГОЛ ЦЕЛИ) is the true course from the RSBN navaid (PR) to the target waypoint (P2).

Target distance             (РАССТОЯНИЕ ДО ЦЕЛИ) is the distance (in km) from the RSBN navaid (PR) to the target waypoint (P2).

ZPU                            (ЗПУ) is a virtual course angle measured at the RSBN navaid (PR) on an orthodromy that is going through the navaid and that is parallel to the orthodromy going from P1 to P2.

The most important thing is that Course angle (ZPU) and target angle are both to be measured at the RSBN station. Though the real course line and the helper line going through the RSBN station are parallel, ZPU is not equal to the initial course measured at point P1 (due to fork). Course angle is continuously changing while flying from P1 to P2, but ZPU remains the same.

Figure 13 - Course angle (ZPU), target angle, target distance and initial course (ZIPU) in the general SRP
mode of RSBN navigation from point P1 to point P2 if the RSBN navaid is at point PR

If Target Angle = ZPU then we have to fly away FROM the station. If Target Angle = ZPU ± 180 (reverse direction) then we have to fly TO the station. In other cases we have to use the general SRP mode. In FROM and TO modes the system has a larger accuracy and as there is a special relationship between Target Angle and ZPU they use different names. ZPU is not used, Target Angle is called as Azimuth and Target Distance is called as Orbita.


Figure 14 - Azimuth and orbita in the FROM mode of RSBN navigation.
Initial course is not equal to Azimuth unless RSBN (PR) is placed at P1.

Setting RSBN parameters

RSBN channel, mode and the calculated data should be set at the RSBN panel of the navigator. Channel should be set on two switches: the upper switch defines the tenths, the lower defines the remainder, so channel 34 should be set as 30 + 4 on the two switches.

In SRP mode set the three values ZPU, Target angle and Target Distance at the right sub-panel. In TO and FROM modes only the left sub-panel should be used to define Azimuth and Orbita. It is worth to set these two values even in SRP mode (Azimuth = Target Angle, Orbita = Target Distance) as the target signals (see later) are bound to these settings. In case of LEFT ORBIT and RIGHT ORBIT modes set only Orbita on the left panel to define the radius of the arc.

Figure 15 - RSBN panel to define (from left to right) channel, mode,
azimuth, orbita, ZPU, target angle and target distance.

For defining azimuth, orbita, ZPU, target angle and target distance you have to click on the left side (decrease) and right side (increase) of the big knobs. Clicking above the center will change the value by 10 degrees/km, below the center by 0.1 degrees/km.

RSBN gauges used in navigation

The RSBN system is not connected to the autopilot, thus it can not fly automatically the defined route segment. The pilot and the navigator use three equipment to manage the plane on the desired route:

RMI indicator         is not frequently installed on An-24 planes, but mostly on An-26s. Its first (yellow) needle can show either an RSBN, the first NDB or the first VOR station bearing. The second (white) needle can show the second NDB or the second VOR station defined on the CURS-MP panel. The selection can be made by two knobs at the bottom of the gauge. The selected navaid type is displayed at the very bottom. The RMI is connected to the GIK gyro and its bearing is always magnetic!

Radio switcher        One should define the data source going to the gauges from the radio switcher on the Radio Panel. It should be in the RSBN or in the RSBN-SP50 position (1st or 2nd) to feed KPPM with RSBN data.

KPPM                      is the gauge used to provide vertical and horizontal guidance with ILS, VOR or with RSBN. Vertical guidance is provided only with ILS. The blinker at the up-right quarter (marked with к) disappears if there is a signal from the RSBN station.

PPDA                       Aircraft bearing and distance relative to the RSBN station. The thick needle shows the ten-degrees on the outer scale. The thin needle shows degrees on the inner scale. It is true (geographic) bearing and it is not the reverse of the bearing to the RSBN station shown by the RMI. The difference is twofold: RMI shows magnetic bearing, and there is a fork between the two locations (aircraft and station). When aircraft bearing equals to Azimuth and distance equals to Orbita, you had reached the target.

Signal lamps            The lower two red lamps are on if there is no Azimuth (left) or Orbita (right) signal from the RSBN station. They should go off if the signal is available. The upper green lamp (left) is blinking if the target defined by  Azimuth and Orbita is within 15 km. The red lamp (up right) goes on if the target is within 1 km.

Figure 16 - Main RSBN equipment for navigation: radio signal selection switch,
KPPM ILS/VOR/RSBN indicator, ADF/VOR/RSBN RMI, PPDA, RSBN signal lamps

The marker lamps are bounded to the Azimut and Orbita values so they should be defined on the left sub-panel of the RSBN panel even if values are set on the right sub-panel in SRP mode.

It has to be emphasized that actual distance is measured on a strait line from the aircraft in the air to the RSBN station so it is longer than the distance measured on a map. Azimut, orbita and the other RSBN values are calculated "on the map" independently from the flight altitude. This would cause strange situations (bias) if orbita is less than 15-20 km. For example in the special situation where the target (P2) is at the RSBN station (PR) the red lamp will never sign if the plane flies above 1 km. On the other hand if you are about flying over the RSBN station the receiver will lose azimuth signal and the bottom left red "missing azimuth signal" lamp will go on. It signs the fly-over with a precision depending on flying height.

In case of larger distances the marker lamps provide quite accurate information. A plane cruising by TAS = 450 km/h will reach the destination within 120 seconds after the green lamp starts blinking and within 8 seconds after the red lamp goes on.

RSBN navigation preparation

Before starting to use any RSBN navigation features you have to perform the following steps:

-          Check main avionics power switch (ПТ-1000), GIK gyro power switch (ГИК-1) and RSBN power switch (РСБН) on the fuser (АЗС) panel.

-          Align GIK gyroscope with magnetic North by pressing the Fast Align button.

-          Switch power on and set latitude on GPK panel.

-          Align GPK gyroscope to GIK (magnetic North) or to true North by using the magnetic declination of the current place. Alignment to true North might be more convenient, as RSBN using true coordinates for azimuth.

Basic RSBN navigation procedures

Main challenges in RSBN navigation are 1/ the question of magnetic versus true courses and 2/ the estimation of difference between starting and arrival courses (fork). Do not forget that Azimuth, ZPU and Target angle should be always defined as true courses! PPDA also shows current true bearing of the plane. On the other hand KPPM shows magnetic heading (unless you set magnetic declination on the navigator's RMI correction ring, but this is rarely done).

As a first step in any navigation procedures you have to establish connection to the selected RSBN station:

-          Define channel on RSBN panel and check signal. Two bottom red RSBN signal lamps should not be on and PPDA should show aircraft bearing and distance.

Flying to the RSBN station on the shortest route

-          On the pilot's RMI gauge switch to RSBN source on the first (yellow) needle and check bearing (magnetic!) to the station.

-          Turn heading to the station and adjust for wind.

This is quite enough for reaching the station, though it is not very precise. If you need more precise navigation, continue as follows:

-          Check  aircraft bearing (true) on PPDA. If the thin - high sensibility - needle is moving clockwise (increasing bearing) then you have to adjust to the right. If it is moving anticlockwise (decreasing bearing) you have to adjust to the left.

-          If the needle is stabilized (your bearing from the station is not changing), then you are flying exactly toward the RSBN station. Read the bearing value (both needles).

-          Set radio source switch to RSBN and check signal on KPPM. Blinker к should be off. The horizontal tracking indicator (vertical bar) should move from the center.

-          Set mode TO on the RSBN panel.

-          Set exact bearing copied from PPDA as Azimuth on the RSBN panel. The horizontal tracking bar (vertical line) on the KPPM should be in the middle and should stay there.

-          Define Orbita as zero or the distance of the target point if it is between you and the station (you will not get the "target is within 1 km" red signal at all if Orbita is zero and if you fly above 1000 m).

-          Stabilize heading by switching AP to GPK mode (or GMK on shorter distances). GPK should be switched on and latitude should be set. Alignment mode (magnetic or true) is indifferent.

-          Time-by-time check KPPM tracking bar and wind drift indicator and adjust course if necessary.

The true course to the station is approximately PPDA Azimuth ± 180°. The difference is the fork between your current position and the RSBN station, because Azimuth is calculated relative to the station. The difference is negligible in shorter distances, but not in case of large distances.

Flying to the RSBN station on a predefined radial

-          Set radio source switch to RSBN and check signal on KPPM. Blinker к should be off. The horizontal tracking indicator (vertical bar) should move from the center.

-          Set mode TO on the RSBN panel.

-          Set inbound radial angle ± 180° as Azimuth. If magnetic radial is given, you have to add magnetic declination at the RSBN station to get desired true radial (Attention: FS Navigator defines declination with bad, opposite sign). This course will be your arrival course, i.e. the course on which you arrive to the station.

-          Orbita is basically indifferent. Set it to zero or to the distance of the target point if it is between you and the station. Even if you fly to the station you might set Orbita to the flying altitude (in km) instead of zero, otherwise you might not get the "target is within 1 km" red signal at all.

-          Check tracking bar position on KPPM and navigate the plane toward the correct track.

-          When tracking bar is closing to the middle, you are to be reaching the track. Turn towards the station and maintain the course by keeping tracking bar in the middle. Adjust for crosswind.

-          To determine course deviation before tracking bar actually moves from centre check  aircraft bearing (true) on PPDA. If the thin - high sensibility - needle is moving clockwise (increasing bearing) then you have to adjust to the right. If it is moving anticlockwise (decreasing bearing) you have to adjust to the left.

-          Stabilize heading by switching AP to GPK mode (or GMK on shorter distances). GPK should be switched on and latitude should be set. Alignment mode (magnetic or true) is indifferent.

-          Time-by-time check KPPM tracking bar and wind drift indicator and adjust course if necessary.

Flying from the RSBN station on a predefined radial

This is nearly the same procedure than to fly to the RSBN station on the predefined course. The main difference are as follows:

-          Set outbound radial angle as Azimuth.

-          Set FROM mode on the RSBN panel.

-          Orbita is basically indifferent. Set it to zero or to the destination of the target if it is on the outbound radial.

Flying to point P2 on the shortest route

If the coordinates of point P2 are not yet defined by their azimuth and orbita (in this case they are called as target angle and target distance) then perform the following steps:

-          Pick up the geographical coordinates of point P2 and of the RSBN station (PR) as well from FS Map or from FS Navigator.

-          Calculate RSBN data (see the Route Planner provided with this document)

Next steps are common regardless of source of the coordinates:

-          Set SRP mode, Target angle and Target distance. Set Azimuth and Orbita also to provide input for the signal lamps.

-          Set radio source switch to RSBN and check signal on KPPM. Blinker к should be off. The horizontal tracking indicator (vertical bar) should move from the center.

-          Change ZPU until KPPM tracking bar moves to the middle position. Be careful: there will be two matching angles opposite to each other. You have to have a general idea on the direction of point P2 to select the correct one. Selecting the wrong angle would result to the "back course" type of reverse behavior of KPPM tracking bar.

-          Turn the plane to the direction of the course. The rough true (!) course will be equal to ZPU, the bias being the - not calculated - fork between your position and the RSBN station. Define heading keeping in mind cross wind.

-          You might double-check yourself based on FS Navigator. Move the mouse cursor over the destination (P2) object (NDB, ISEC point, custom waypoint, airport etc.). An info-box should appear and the second line from the bottom will show "Fly to course". This is the correct magnetic (!) course you should select at your current position. Set heading keeping mind cross wind.

-          Set AP mode to GPK. GMK mode can be used for shorter distances only.

-          Adjust and follow track based on KPPM signal. Keep track of cross wind.

Flying to point P2 on a predefined course

This is a rather complex process and in most of the cases can be defined as flying from point P1 to point P2. Perhaps the plane will join the P1 - P2 segment somewhere in the middle only, but it is not a real difference.

Flying from  point P1 to point P2

-          Pick up the geographical coordinates of the two points and of the RSBN station (PR) as well from FS Map or from FS Navigator.

-          Calculate RSBN navigation data (see the Route Planner provided with this document)

-          Calculate true or magnetic start course with Route Planner.

-          Define mode and set all relevant data on the RSBN panel. Set azimuth and orbita even in SRP mode to provide input for the signal lamps.

-          Set radio source switch to RSBN and check signal on KPPM. Blinker к should be off. The horizontal tracking indicator (vertical bar) should move from the center.

-          Check GPK latitude setting and GIK/GPK gyroscope alignments.

-          Set Auto-pilot (AP) mode to GMK or GPK.

-          Prepare initial course (adjusted by cross wind slip) on the GPK Turn Indicator.

-          When approaching point P1 the horizontal indicator bar on KPPM should be moving to middle position.

-          At this point or a bit before (depending on turn angle) switch AP to Turn mode, or perform the turn manually.

-          Set AP mode to GPK (as the radial defines an orthodrome). GMK mode can be used for shorter distances only.

-          Adjust and follow track based on KPPM signal. Keep track of cross wind.

If initial heading is set correctly and is maintained by GPK and if crosswind is not changing then the plane will follow the track to point P2. In realistic situations however track should be checked on KPPM time-by-time and heading should be adjusted. Bias is originated from the following reasons: not absolutely precise initial heading setting; GPK gyro alignment errors; cross wind change.

Autonomous Navigation System (NAS-1)


NAS-1 (НАС-1, Навигационная автономная система) is an autonomous system in a sense that is does not require any external radio signal transmitters to keep track of aircraft route. It is using a Doppler radar equipment DISS (ДИСС, доплеровского измерителя путевой скорости и угла сноса) that is emitting radio signals and checking mirrored waves. It measures aircraft speed (TAS) and also slip (course and heading difference) generally caused by cross wind. Accuracy is 0.5% for speed and ±20' for slip measurement.

With the help of the GPK gyroscope NAS keeps track of the movement of the plane and updates its coordinates in a Cartesian (X-Y) coordinate system. It is even capable of drive the plane along a predefined course - and compensating wind! - via the Automatic Control system SAU (САУ, системы автоматического управления) which is connected to the lateral control channel of the autopilot.

Figure 17 - We generally keep track of aircraft position as distance on route and
lateral deviation from route, but there are other options as well.

The NAS-1 gauges

Main controls of the NAS system can be reached from the navigator's seat. The main NAS panel will overlay the RSBN panel.

Figure 18 - NAS-1 control equipment with hot-spots: Map angle selection gauge, Counter switch, Cartesian coordinates counters (Y, X and YX counters), Reset All Counters icon,
Speed/Slip counter and Lateral Deviation/Automatic Control gauge.


Counter switch           turns on aircraft co-ordinates tracking. All other NAS functions are working even if this switch is off.

Map angle                  Here you can define the direction of the coordinate axis "C" (Y) relative to the reference direction defined by the GPK gyroscope. This is generally true North, magnetic North or the actual route segment course.

Plane coordinates      The two needles of this gauge shows aircraft coordinates relative to the reference point (where the gauge was reset or set manually). Needle "C" is named by North (Север), needle "B" is by East (Восток). You can consider them as coordinates Y and X respectively. Coordinates are given as 10 km-s from the reference point in Y and X directions. The additional counter at the top shows 1000 kms.

Y coordinate

X coordinate              These two additional gauges show Y and X coordinates from the reference point in 10 m resolution (the small needle in the inner scale shows kms). These gauges will overlap the low resolution "Plane coordinates" gauge. You can switch among the three gauges by clicking on the three hot-spots (СЧЕТНИК С-В, СЧЕТНИК С and СЧЕТНИК В) at the bottom-right of the NAS panel.

Reset coordinates     Clicking on this hotspot (right-bottom of panel) will reset all counters at once.

Speed/slip counter     displays aircraft speed (TAS) and slip as reported by DISS Doppler radar equipment.

Lateral Deviation      On this gauge (ЛБУ, линейное боковое уклонение) you can define the known lateral deviation (in km) of the plane relative to the desired route. Set deviation on the knob at the right (in 0.5 km resolution). Pushing the left button will turn on the Automatic Control (САУ). The green lamp at the bottom will go on and the system will control the lateral channel of the Autopilot. Automatic Control will maintain the course (not heading) defined by the "C" (Y) axis (= Map angle).

Coordinate counters can be reset by clicking at the centre of the gauge by the mouse. The four values ("B" and "C" on the default counter, "B" on the "B" counter and "C" on the "C" counter) can be reset individually. To reset all counters at once click on the hotspot below the CB counter.

Map angle and aircraft coordinate counter

NAS-1 is keeping track of aircraft movement using the DISS Doppler radar. Raw result is shown by the speed and slip gauge. Using the GPK gyroscope axis as reference direction NAS-1 keeps track of aircraft coordinates in a Cartesian coordinate system Y axis being the direction defined by GPK and X axis being the perpendicular direction. The axes are called as "C" and "B" (Север and Восток). Coordinate units are kilometers (meters on the high resolution gauges). Y axis points toward either true North or to magnetic North depending on GPK gyro alignment.

The coordinate counters are set to the desired value (generally zero) at a reference point whose real geographical coordinates are known. When the plane flies over the point you turn the counter switch on and coordinate tracking starts. Alternatively you reset the counters when flying over the reference point.

Figure 19 - Aircraft coordinates can be read from the two needles of the counter gauge
as distances from the reference point toward North (C) and East (B) directions.

During aircraft navigation it is generally more natural for the pilot and for the navigator to see the coordinates as distance on route and lateral deviation from route. This is possible by rotating the coordinate system (map) to the route course. This angle is called as Map angle (угол карты) and can be set by a special gauge with a resolution of 0.25°. Map angle is measured relative to true or magnetic North whichever is defined by GPK.

This coordinate system makes it possible for NAS-1 system to send control signals to the Autopilot system. The lateral channel of AP will receive route deviation information and will maintain the aircraft on the desired route (see next chapter).

Figure 20 - The coordinate system is rotated towards the route course, thus Y and X ("C" and "B") coordinates show distance on route and lateral deviation from route respectively.

Automatic control and lateral deviation

Automatic Control  (САУ, система автоматического управления) is a special function of NAS-1. It is able to send signals to the horizontal channel of the autopilot, thus it is able to navigate the plane horizontally. It sends signals to the AP based on the calculated lateral deviation. Deviation is started calculating relative to the course defined by map angle as soon as Automatic Control is turned on. Map angle is relative to the alignment of the GPK gyro and movement is measured by the DISS Doppler equipment.

Turn on Automatic Control by pressing the left button on the Lateral Deviation control. The green lamp at the bottom will go on and the lateral channel of the autopilot will be controlled to keep lateral deviation zero. The coordinate Counter switch setting has no effect on the operation of the Automatic Control.

If the current course is not parallel with the Y ("C") coordinate of the map (map angle) when you turn on Automatic Control or if you manually change map angle (you rotate Y axis) while Automatic Control is on, then the plane will maintain a coordinated turn to align to the new Y axis. As turn can not be made in place, while turning it will gather some lateral deviation thus Automatic Control will overturn and bring back the plane to zero deviation.

If you manually set lateral deviation while Automatic Control is on, or if it is not zero when Automatic Control is turned on, then the plane will perform coordinated turns and passes over a parallel route where lateral deviation is zero.

Autopilot should be on to work with Automatic Control. AP can work in any modes, practically either in GPK or Turn modes. Switching from GPK to Turn mode however will turn off Automatic Control. While in Turn mode turning Automatic Control on will suspend (!) Turn mode, but it will be reactivated as soon as you turn off Automatic Control. It is a good practice to set back mode from Turn to GPK while flying under Automatic Control to avoid unwanted effect when turning the control off.

Rotating the Turn (banking) Knob ("РАЗВОРОТ") will also switch off Automatic Control. Automatic Control can not be switched on while Turn knob is not in neutral position. This means that when we would like to effectively combine Automatic Control with turns, we have to use GPK Indicator to perform the turn instead of the Turn knob.

Basic NAS navigation procedures

NAS is a complex system providing information on aircraft speed, slip, aircraft coordinates and lateral deviation from desired route. It can also control the lateral channel of the Autopilot. It can be used in a variety of situations in aircraft navigation.

NAS system is using the GPK gyroscope for keeping track map axes. You have to prepare GPK gyro before using NAS:

-          Turn on main GPK switch, set average route latitude and align the gyro with any meaningful direction. It is generally GIK (magnetic North) or true North.

Keeping track of cross wind

Cross wind causes the plane deviate from its desired course. You must turn a bit toward the direction of the wind and slip the plane to remain on track. The required slip angle depends on wind speed and direction. NAS Doppler radar system keeps track of slip which is generally caused by cross wind and displays it as degrees of slip. Positive (right) slip should be compensated by a similar amount of decrease (left) in aircraft heading and vice versa. If desired course is 40° and slip is +7° then heading should be 33°.

It should be noted that wind direction and speed information is not directly available.

-          Turn the plane heading toward the desired heading.

-          Check slip angle, deduct it from the desired heading and adjust heading

-          In case of larger slip the heading correction might effect the slip, so you might have to retune heading again.

-          Time-by-time check slip and correct heading.

Flying from point P1 to point P2

Hereby we assume that point P1 is the initial waypoint of the route right after taking off. We also assume that you will be able to detect when flying over point P1. It is wise to use an NDB, VOR or RSBN station around the take-off airport as first route waypoint.

-          Pick up the geographical coordinates of the two points from FS Map or from FS Navigator.

-          Calculate NAS navigation data (see the Route Planner provided with this document)

-          Check and turn off NAS Counter switch.

-          Reset all coordinate counters (check high resolution counters as well). Be sure that Lateral Deviation control is reset as well.

-          Set initial course segment as Map Angle.

-          If you would like to use Automatic Control, then turn Autopilot on and set mode to GPK.

-          When flying over point P1 turn NAS Counter switch on. You might turn Automatic Control as well.

Correcting lateral deviation

In spite of its good precision NAS system will collect a relevant amount of bias during longer journeys. That's why it is a good practice to check correct aircraft position based on external references whenever it is possible. You should make a note on the bias of both coordinates and perform necessary correction. Bias on the Y coordinate ("C") does not effect current course, but on the X coordinate ("B") it does.

To make the manually correction when Automatic Control is off, follow the next steps:

-          Calculate lateral deviation from the desired track using external information (visual, radio signals etc.).

-          Make sure NAS Counter switch is on.

-          Switch to the high resolution X coordinate ("B") counter. It should be more-or-less stabilized as you are flying the correct course, though with a lateral bias. It might show zero meters even if you had deviated from the track (that's why it is a bias of the NAS system).

-          Set the calculated X coordinate on the gauge. It should be set as positive value if you are right form the desired track and vice versa. Now X coordinate will be correct, though you are still flying on a parallel track.

-          Bring the plane towards the desired track. You reach the track when X coordinate becomes zero.

-          Set original heading to follow the track. X coordinate should stabilize on zero.

To make the correction using the Automatic Control follow the next steps:

-          Calculate lateral deviation from the desired track using external information (visual, radio signals etc.).

-          Check whether Automatic Control is on.

-          Set bias on the Lateral Deviation gauge. It should be set as positive value (right) if you are right form the desired track and vice versa. Automatic Control will use appropriate banking to perform the turns.

Figure 21 - Track correction using the Lateral Deviation gauge.

Using full Automatic Control you can make lateral corrections by a 500m resolution only. This is generally precise enough, but if you have to make more precise corrections, then use a combined method:

-          Set exact calculated bias as X coordinate "B" (for example -800m).

-          Set lateral deviation to the next higher 500m unit (-1 000m in this case).

-          Check X coordinate counter ("B") when Automatic Control performs correction and when it reaches zero, reset lateral deviation (by clicking on the middle of the gauge).

-          The aircraft will overrun by not more than hundred meters but will return back to the correct track automatically.

Changing to a parallel track

The following maneuver is frequently used to fly around stormy areas. You go to a parallel track and then return back to the original one. The maneuver is basically using the "lateral deviation correction" scheme, though there is no "deviation" in its strict sense here.

The maneuver can be done manually as well, but here we describe automatic mode only:

-          Check whether Automatic Control is on.

-          Set Lateral Deviation to the desired value. Setting a positive (right) value will cause the plane to switch to a parallel track left to the current one and vice versa. Automatic Control will use appropriate banking to perform the turns.

-          After bypassing the dangerous area you might switch back to the original track by defining an opposite lateral deviation of the same magnitude.

Correcting track using RSBN/VOR information

One of the most precise methods of correcting coordinates maintained by NAS is using a VOR or RSBN station. Hereby we will use the navaid to determine lateral deviation.

Figure 22 - Estimating lateral deviation as a difference between calculated distance
to a VOR/RSBN station and actual DME/PPDA distance. Bearing to the station should
be perpendicular to the actual course to make calculation as easy as this.

-          Select a navigation aid (VOR/DME or RSBN) that has a bearing perpendicular to the actual route segment not far ahead of you.

-          Calculate the check point (Px) and determine its distance from the radio station.

-          Check RMI (VOR) or PPDA (RSBN) to capture the moment when you see the station at 90° relative to your course. You might set course on Course-MP (VOR) or Target Angle/Target Distance (RSBN SPR mode) and use KPPM to see when you cross the radial.

-          Read actual navaid distance from DME (VOR) or from PPDA (RSBN).

-          Deduct difference between calculated and actual distances to get lateral deviation.

-          Use method "Correcting lateral deviation" to go back to the desired course.

Turning to next route segment        

Turning from P1-P2 route segment to P2-P3 segment is a complex procedure. We have to change map angle and also have to reset coordinate counters. Practically you can not do these things parallel. Changing map angle is itself time consuming and while the knob is in intermediate position all coordinate counting and lateral deviation calculation will be more-or-less meaningless or at least biased.

In some other aircraft types there is an active and a parallel passive set of the NAS control equipment. One set is controlling the plane, and on the other you set the new values. You just switch between the two sets when appropriate.

On AN24-RV the best would be possible to turn off NAS (both coordinate counter and Automatic Control) at a calculated distance before point P2, change all settings and turn on NAS when flying over point P2. Fly-over moment can be estimated using a chronometer. When you turn off NAS, you start chronometer and based on aircraft speed you will know when you reach P2. In 10 seconds the plane will fly over 1 - 1.4 km depending upon actual speed.

We will not use this method. The methods described here are simpler and would lead to satisfactory results in most situations. We will generally concentrate on fast changing of map angle and will possibly reset Y ("C") counter. We will also let Automatic Control to turn the plane.

The novice method

In this section we define the most straightforward method. We will start turning only when flying over P2. This method is effective when turn angle is less than 30°.

-          At waypoint P1 reset coordinate counters.

-          Follow exactly the P1-P2 track by maintaining X coordinate as zero. If you use Automatic control, it will do this automatically. If X coordinate is not zero, you will not fly over point P2 at all.

-          While on P1-P2 route segment, check Y coordinate ("C"). When it reaches distance between P1 and P2, you are actually reaching P2.

-          When you see on the Y ("C") counter that you are above point P2 change map angle fast to the new P2-P3 course. Automatic Control will start turning the plane immediately.

-          Reset Y ("C") counter as you did at point P1 as well. Do not bother with X ("B") coordinate.

-          The plane of course overrun the P2-P3 track, but will return to it automatically. At first both X coordinate and lateral deviation will increase. Lateral deviation is shown by 0.5km resolution only, so increase will not be generally visible, but it is increasing and exactly this is that will force Automatic Control to bring the plane back to the right track.

-          As the plane returns back to the P2-P3 track X coordinate and lateral deviation will decrease to zero.

Figure 23 - Novice turn (P2) and advanced turn (P3) using NAS-1. See details in text.

We can further simplify the procedure if we do not reset Y ("C") coordinate at the turn. It will grow from the beginning of the route till the end. We calculate Y ("C") coordinate cumulative i.e. adding each segment length to the previous ones, so that we will know when to turn. This way we should only concentrate on the map angle change at the turning point.

The advanced method

This method is to be used for turn angles greater than 30°. In this situation "novice method" would result too big overruns and long correction turns. Instead of flying over the waypoint we start turning in advance.

We have to define the turn starting point P3' based on turn angle and on aircraft speed. Larger turns and speeds require larger distances. We have to start turning above point P3'. We have to change map angle also to the next route segment course, so we will already fly in the new coordinate system. Coordinates of P3' are not Y=0, X=0 in the new coordinate system. Exact values should be calculated when planning the turn. In the new coordinate system starting Y (C) coordinate will be negative in case of turns smaller than 90° (we are "behind" point P3), positive otherwise (we are "ahead" of point P3). New starting X (B) coordinate will be negative on left turns (we are left to the desired track), positive on right turns (we are right to the track).

Figure 24 - Starting (P3') coordinate signs in case of different turns

These setting changes can not practically be done fast enough on the single active NAS control gauges of the AN-24RV, unless we have a fast and experienced navigator.

Such a simulated navigator is recently under development in the form of an "Auto-Navigator" panel. Through this panel the pilot will be able to read the prepared data from file and will be able to load them into the gauges by a simple button press when flying over the waypoint.

The simplified advanced method

If we are not fast enough to make the changes on the NAS gauges, we can simplify the operation with some in advance calculations again: we calculate cumulative Y coordinate as in the "novice method" but count also extra or minus distance resulted by the advanced turn procedure. This way we do not have to set/reset Y coordinate. We also change the procedure to avoid X coordinate setting. We will do turning automatically:

-          Follow exactly the P2-P3 track by maintaining X coordinate as zero. If you use Automatic control, it will do this automatically. If X coordinate is not zero, you will not fly over point P3' at all.

-          While on P2-P3 route segment, check Y coordinate ("C"). When it will reach cumulative distance value to P3', you will be actually reaching P3'.

-          When you see on the Y ("C") counter that you are above point P3', change map angle to the new P3-P4 course fast. AP will start turning the plane immediately.

-          At this point Automatic Control assumes that we changed map angle on the new track and starts calculating lateral deviation resulted by overrun. But in this case it is not true, we did not overrun yet as we had started turning before reaching the new track. We have to let AC know about that when we had changed map angle we had an intentional lateral deviation from the track.

-          In theory while changing map angle we also has to set lateral deviation on the Automatic Control/Lateral Deviation gauge. This is practically impossible and AC immediately starts summarizing false lateral deviation. No problem: if we know that for example we have to set a 3.5 km positive lateral deviation, we change map angle and after that we click 7 times on the right side of the lateral deviation setting knob. Each click will increase lateral deviation by 0.5 km, thus the total correction will be 3.5 km.

-          Automatic Control will turn the plane to the new direction calculating predefined lateral deviation as well and finally it should approximately reach the new track.

Using Automatic Control to maintain the actual course

We can use Automatic Control to stabilize a course we defined using by any means. The big plus of Automatic Control over AP GPK mode is the automatic handling of cross wind changes.

-          Set the desired course based on any navigational information

-          Set GPK  mode on AP to maintain heading for that course

-          Set the approximate course as Map angle

-          Turn NAS Counter switch on and steer the high resolution X ("B") counter.

-          If counter is increasing (right deviation) then increase map angle, otherwise decrease it, until counter stabilizes. You might reset the counter meanwhile to keep it around zero for clarity.

-          Stabilized counter "B" means that we had found actual course and we had set it as map angle successfully.

-          Turn Automatic Control on to maintain the course set as map angle.

-          From this point on counter "B" will be zero. However this will not guarantee that we reach our target. We had only stabilized the initial course. Precision will be only as accurate as precise the initial course was.

Capturing a VOR radial

-          Set VOR frequency and desired radial (course) on Course-MP.

-          Align GPK with GIK as Course-MP is using magnetic bearings.

-          Set the same course angle to map angle (Automatic Control is off yet). This is not absolutely correct as your desired magnetic course differs from the bearing by fork and by magnetic declination difference between the VOR and your present location. For shorter distances on lower latitudes correction is not necessary.

-          Check KPPM and drive the plane to cross the radial.

-          When crossing the radial turn Automatic Control on. You might also turn on NAS counter switch and check "B" counter, though this is not necessary. Automatic Control will turn the plane onto the radial, will correct possible overrun and will maintain the course.

Figure 25 - Capturing a VOR radial and stabilizing the course using NAS Automatic Control.
For shorter distances correction with fork and magnetic declination difference can be omitted.

Capturing an RSBN radial

-          For inbound radial set RSBN channel, set mode TO and set desired radial ± 180° to Azimuth (azimuth is the direction from the station) on the RSBN control panel. For outbound radial set mode FROM and set radial to Azimuth.

-          Set radial as map angle. RSBN is using true bearings, so GPK should be aligned to true North. If GPK is aligned to GIK (magnetic North) than you have to calculate and set magnetic bearing which is true bearing minus magnetic declination. This is not absolutely correct as your desired true course differs from the bearing by fork between the RSBN station and your present location. For shorter distances on lower latitudes correction is not necessary.

-          Drive the plane toward the desired track based on KPPM.

-          Check when KPPM tracking bar moves to the middle. Exact crossing moment can be recognized by steering the PPDA bearing needles. When they show the defined azimuth (i.e. aircraft bearing from the station is equal to the defined azimuth) then you are crossing the radial.

-          When crossing the radial turn Automatic Control on. Automatic control will turn onto the radial, will correct possible overrun and will maintain the course.

Summary on courses, bearings and radials

Most of misunderstanding around navigation originates from the mixture of the different coordinate systems or reference directions. Different navigation equipment unfortunately use different coordinate systems.

We are basically working with three coordinate systems for courses and radials. Magnetic course is relative to the magnetic meridian at the actual point (do not forget to align your GIK). The aircraft bearing you read from PPDA and the azimuth you set are relative to the true meridian at the RSBN station. And finally orthodromic course you read from your GPK. This is used by NAS and by AP in GPK and in Turn modes and it is relative to the reference meridian (the true or magnetic meridian at the point where you had aligned GPK) and are loaded by collected fork. There is a 4th type of course that is not really used - it is the true course that is relative to the true meridian at the actual point. This is not shown by any equipment, but can be calculated based on magnetic course and declination, or based on orthodromic course and fork:

Figure 26 - Magnetic, true, orthodromic courses and azimuth. Meridians are labeled as:
T = true meridian at actual point, M = magnetic meridian at actual point and R = reference meridian parallel at (true) meridian at DALNA. Meridian (true) convergence is enlarged for better visualization.


We arrived from DALNA to SUNIT and we would like to fly towards the ARKHANGELSK RSBN station on the 60.0° inbound radial. At DALNA we aligned GPK to the true North. From that waypoint we had already collected ­2.8° fork. The fork between the actual point and the RSBN station is ­3.1°, so by the time we reach the station our total fork will be ­5.9°. Magnetic declination at SUNIT is +11.5°, at the RSBN station it is +13.4°. What will we see on different equipment and what direction we should follow based on the different equipment?

The situation is shown on the figure above. Values might differ one value in the decimal digit because of rounding (calculations were done using more decimal digits).

PPDA will show 60.0° + 180° = 240° azimuth (aircraft bearing) and you have to set 240.0° as Azimuth and mode TO on RSBN to see the correct track on KPPM.

True course (ZIPU) is 60.0° - 2.8° = 56.9°. If you follow the radial based on KPPM, this direction will change and when you reach the station it will be 60.0°. Raw true direction is not shown by any equipment, so it is generally not used.

Magnetic course (ZMPU) is true course minus declination: 56.9° - 11.5° = 45.4°. You see this on the RMI or on the magnetic compass (if no wind). This value will change while you proceed toward the station and there it will be 60.0° - 13.4° = 46.6°.

Your orthodromic course (OZIPU) is true course plus fork: 56.9° + (-2.8°) = 54.1° and you have to follow this course on the GPK Indicator (if no wind) and you have to set this value as Map Angle on NAS (regardless of wind). See, this value can be calculated also as arrival true course plus fork at ARKHANGELSK: 60.0° + (-5.9°) = 54.1°.

As an alternative we might align our gyro to magnetic North instead of true North at DALNA. In this case our orthodromic course (OZMPU) is true course minus magnetic declination at DALNA (!) plus fork: 56.9° - 9.5° + (-2.8°) = 44.6°.

The Route Planner

Route Planner is an MS Excel based tool to calculate navigation data mainly for AN-24RV aircrafts.

Present version of Route Planner was tested on FS9 and on the Northern hemisphere only.

General instructions

Calculation of input data for NAS and RSBN gauges based on the waypoint coordinates is not trivial. We developed an MS Excel based tool - the Route Planner - that calculates all necessary information and also provides some additional functionalities:

-          Loading and saving route plans

-          Importing flight plans composed in FS or in FS Navigator

-          Exporting route plan for the "Auto Navigator"

-          Loading interpolated magnetic declination values from FS

-          Selecting RSBN stations from an editable database

-          Working with either magnetic or true coordinates

-          Hiding/displaying data column groups

-          Calculating all NAS and RSBN data

-          Calculating NAS data for the "simplified" navigation method

-          Calculating turn parameters

-          Calculating route segment flight duration

-          Various additional calculation utilities (might change in different versions)

Figure 27 Part of the Route Planner screen with sample flight data

The Route Planner was developed using VBA. Though we tried to make as many checks as possible, it is not fool-proof. The application is under tests and new version might appear as bugs are fixed.

So many input and output data exist that we provided a menu to hide and display data groups individually. In some cases sub-groups of data can be hide/display independently of their parent data (geographical coordinates, rolled length and duration data, NAS counter start values).

From the menu you can also clear, load and save the route plan. Route plans are stored in standard CSV file format. FS9 flight plan files can be imported directly. FS Navigator files should be exported to FS flight plan before importing them to the Route Planner. Route plans can be also exported to be used with the Auto-Navigator presently under development.

Waypoints can be deleted and additional waypoints can be inserted by defining the waypoint number and pressing the "Delete" or "Insert" buttons. "Insert" duplicates the selected waypoints. One of the instances should be modified with the data of the new waypoint.

You can retrieve magnetic declination for the waypoints by pressing button "Actual" (for the selected waypoint) or "All" (for all waypoints). Data is retrieved from FS database (magdec.bgl) and correct declination is calculated using two-dimensional linear interpolation to achieve better accuracy for magnetic course (ZMPU, OZMPU) calculations.

Pressing the "Calculate" button will re-calculate route data. After making any changes on the input data do not forget to recalculate as it is not done automatically.

As entering waypoint data manually is quite difficult use import instead. However RSBN data are not included in FS flight plans, they should be added within the Route Planner. You can select RSBN stations from a predefined list. The RSBN station database itself is stored on the "RSBN" worksheet of the Route Planner. It can be modified and can be saved to file (standard CSV format).

Figure 28 - The database of the RSBN stations can be
edited and saved on the "RSBN" worksheet of the Route Planner


Calculated data were tested against FS Flight Planner and against FS Navigator and during several test flights under critical circumstances (Near to true and magnetic North Poles, cross-pole flights, East and West hemisphere.

This version however were not tested on the Southern hemisphere though calculations are most probably OK. Anyhow the GPK gyroscope can not be used there because Southern latitudes can not be set on the GPK panel (see GPK description).

Route Planner is providing the same ZMPU values as FS Flight Planner even in the most extreme situations, where FS Navigator might have an enormous bias. This is achieved by a precise Earth model and by the two-dimensional interpolation for magnetic declination values for the waypoints. To achieve maximum precision do not enter magnetic declinations manually, but use the function to read them from the FS database. This function also performs the interpolation.

In several navigation documents the following formula is used to define (true) fork:

where φ is geographical latitude and λ is altitude of points P1 and P2. However this formula is an approximation only for situations where latitudes are not changing wildly. On higher latitudes or for long distance flights this equation gives wrong results. In Route Planner we calculate fork with a precise formula instead of this, so Route Planner is not effected by the bias mentioned here.

Calculations are done using double precision floating point numbers, but results are displayed only with precision supported by the aircraft equipment.

Data column description

Route Planner is a newly developed application. It will go under careful tests and its structure might slightly change in the subsequent versions. In the column description below type is defined as I=Input and O=Output.






Basic data about the current waypoint. This waypoint is the starting point of the current segment.



Simple sequential identifier of the waypoint. It is mainly used when defining the waypoint for deletion or insertion. Not to be edited.



The descriptive name of the waypoint. It can be any string. Imported flight plans contains the ICA code as name extended by the waypoint type description (airport, ISEC, VOR or NDB).



Hemisphere (N=North, S=South), degree and minutes in three separate columns



Hemisphere (E=East, W=West), degree and minutes in three separate columns

Mag. decl.


Magnetic declination of the waypoint. Be careful: FS Navigator displays magnetic declinations with a wrong sign. Reverse sign read from FS Navigator before appending here.

For more precise calculation let Route Planner to load magnetic declination values from the corresponding FS9 BGL file directly. It will also perform two dimensional linear interpolation to define more exact declination for the waypoints.



Variety of options for the current waypoint

 GPK alignm.


Alignment of the GPK gyroscope (None, Magn, True) at this waypoint. It is either aligned to the magnetic North (using either GIK gyro or magnetic declination info) or to the true North. You might not re-align the GPK gyro during longer segments on your route, but it is obligatory to align it to true or magnetic North at the first waypoint.

Turn Ctrl


Turn method for this waypoint (Waypnt, In adv). Turn is either started when flying over the waypoint (Waypnt) or in advance (In adv). Calculated turn parameters are displayed in the "Turn Control" output column group.

NAS cntrs


NAS counter handling method (Reset, Rolling) at this waypoint. The counters are either set/reset at the waypoint (Reset) or they ("C" counter) are not reset but summarized (Rolling) over subsequent route segments. In either case the calculated actual NAS data is displayed in the "NAS Data" column group.



Ground speed of the aircraft in km/h. It is used in turn and duration calculations. Besides flight duration speed affects required turn parameters (distance, banking etc.).



RSBN station parameters

Long name


Name and channel of the RSBN station if any. Selectable from the RSBN database. After selection other RSBN station parameters are filled automatically.

Abbr name


Abbreviated name (code) of the RSBN station. Filled automatically from the RSBN database. This code is transmitted via Morse signals.



Hemisphere (N=North, S=South), degree and minutes in three separate columns. Filled automatically from the RSBN database.



Hemisphere (E=East, W=West), degree and minutes in three separate columns. Filled automatically from the RSBN database.



Raw true course data for calculations

Crs >>


Starting true course angle from the waypoint in degrees. This value is called as ZIPU.

>> Crs


Arriving true course angle to the next waypoint in degrees.

>> Fork


Fork between the actual waypoint and the reference meridian. The reference meridian is the meridian that goes through the last waypoint where we had aligned the GPK gyro (with either magnetic or to true North). If we are not aligning the GPK gyro through several subsequent waypoints, it will be still relative to the last reference meridian. All courses defined by GPK will differ from the real reference direction by the >> Fork defined here.



Fork between the actual and the next waypoint in degrees. Fork is caused by the meridian convergence. True fork is equal the difference of the starting and arriving true course angles. Used to be denoted as ΔA.



Length and duration data for the current segment and also rolled from the beginning.



Length of the route segment starting at the actual waypoint in km. Length is measured on the great circle (orthodrome).



Flight duration of the route segment on the great circle calculated based on the given aircraft speed.

Rolled Length


Total calculated route length from the starting waypoint.

Rolled duration


Total calculated flight duration from the starting waypoint.



GPK and GIK based courses. GPK must not be re-aligned during the flight unless it was planned and calculated.



Route segment orthodromic course pointed by the GPK gyro. The value here takes into consideration the previous alignment (magnetic or true) and all colleted fork. This course angle is not changing from the starting waypoint to the next one. In fact we fly the orthodrome based on the fix course shown by the GPK gyro.

This value is called as OZIPU or OZMPU depending on whether the reference meridian is true or magnetic.

GPK fork


Magnetic fork of the GPK gyro. While true fork shows the declination from the true North, this value shows it from the magnetic North. It is calculated only if magnetic declination of the waypoint is provided. If your GIK is not working you can define any magnetic course by subtracting this value from the desired magnetic course and follow that direction on GPK. Used to be denoted as ΔMY

Mag >>


Starting magnetic course angle from the waypoint in degrees. It is calculated only if magnetic declination of the waypoint is provided. This value is called as ZMPU.

>> Mag


Arriving magnetic course angle to the subsequent waypoint in degrees. It is calculated only if magnetic declination of the waypoint is provided.



NAS settings to be set on the gauges for the current segment starting at this waypoint



Map angle in degrees. Map angle is relative to any reference directions, but if NAS is used in conjunction with RSBN it is wise to use true directions. Map angle defines the direction of the Y (C) axis of the NAS coordinate system.

C >>


Y (C) coordinate (km) to be set at the start of the actual segment. It is 0 if you had started turning above the actual waypoint. It is negative if the turn was smaller than 90°, positive otherwise.

B >>


X (B) coordinate (km) to be set at the start of the actual segment. It is 0 if you had started turning above the actual waypoint. It is negative if you had turned left, positive otherwise. See the detailed turning scenarios about how to use X counter if you use rolled (summarized) Y counter values.

>> C


Y (C) counter value (km) defining the end point of the present route segment. It can be a rolled (summarized) value if the "Rolling" option is used. It takes into account turn control method (Waypnt or In adv) also. You have to start turning to the next segment when you see this value on the Y counter.



RSBN settings to be set on the gauges for the current segment starting at this waypoint

Chan num


Channel number to be set. RSBN gauges requires setting of channel number instead of frequency. Channel 1 means 116.00 MHz and channels are divided by 0.05 MHz.



RSBN operation mode. TO if we are flying towards the RSBN station, FROM if away from it. We use the less accurate general SRP mode when the next waypoint does not lie on an RSBN radial.



True bearing of the next waypoint from the RSBN station. In TO and in FROM modes this value should be set on the Azimuth gauge. In SRP mode this value should be set on the Target Angle gauge, though it is worth to set it on the Azimuth gauge as well as the target signals are based on Azimuth and Orbita settings in all three modes.



Destination of the next waypoint from the RSBN station. In TO and in FROM modes this value should be set on the Orbita gauge. In SRP mode this value should be set on the Target Distance gauge, though it is worth to set it on the Orbita gauge as well as the target signals are based on Azimuth and Orbita settings in all three modes.



Course angle to the next waypoint. The actual course angle is continuously changing as we fly between the two waypoints. The ZPU angle is the fix angle that is measured at the RSBN station on the route line parallel of the real route segment.



Calculated turn parameters for in-advance turn at (before) this waypoint. These parameters are calculated regardless of Turn Control option setting. If you see large angles and distances here you might set "In adv" Turn Control for the waypoint.



Turn angle at this waypoint in degrees. Left turn is negative, right turn is positive.



Recommended banking angle in degrees.



Recommended distance ahead of this waypoint to start turning. In case of larger turn angles and larger speeds this value could be several kilometers.



Duration of the turn in seconds, i.e. the time you fly on the arc from the starting of the turn until you end up on this route segment.


RSBN database description

The RSBN database is located on the RSBN worksheet of the Route Planner. It can be modified and saved to standard CSV format files.




Channel count. RSBN gauges requires setting of channel number instead of frequency. Channel 1 means 116.00 MHz and channels are divided by 0.05 MHz.


Name and channel of the RSBN station.


Abbreviated name (code) of the RSBN station. This code is transmitted via Morse signals.


Frequency (MHz)


Hemisphere (N=North, S=South), degree and minutes in three separate columns.


Hemisphere (E=East, W=West), degree and minutes in three separate columns.


Calculated column, not to be modified. This column is used as the lookup list for RSBN station selection on the main sheet.


The attached rsbn_cis_fs2004.csv database file is based on the FS2004 RSBN scenery for CIS (recently used stations). See scenery details in the Appendix.

Sample flight (UKLI, Ukraine)

Route: UKLI (Ivano-Frankivs'k Rwy 28) - STRY RSBN 11k - L'VIV NDB 315.0 kHz - ZOLOCHIV NDB 265.0 kHz - SOLNU - GURMA - D101H - UKLI Rwy 28 ILS 109.3 MHz

During this flight one can learn all features described within this document. It can be managed using NAS only or it can be combined with RSBN. Hereby we describe one scenario using both navigation systems and a combination of turn procedures. As we will extensively use RSBN - that is using true directions - we will align our GPK gyro to the true North instead of the magnetic one. Follow the instruction carefully at first and then combine possibilities at subsequent tests.

Throughout the flight we are using the standard FS9 scenery. We should only add the RSBN scenery defined in Appendix A.

Flight planning

-          Open the Route Planner and Import the included "UKLI_Navigation_Test.pln" flight plan.

-          Each line consists of a route segment except the last one. For example line 4 defines the segment ZL-SOLNU. The last line only defines the end of the route, it is not a segment itself.

-          Load magnetic declination values by pressing the "All" button at the magnetic declination menu section. We will only need declination for the airport, but we can load it for all waypoints. It will make it possible to check some additional functionalities.

-          Notice that segments 2-6 are interesting for us only. Segment 1 UKLI-BP1 is not controlled yet, you fly to BP1 using normal departure procedures. Segment 7 D101H-UKLI is the ILS approach already. Line 8 UKLI is not a segment as there are no further waypoints at all.

-          Assign STY [11k] RSBN station to waypoints BP1, LO and ZL and station IVANO-FRANKOVSK [20k] to SOLNU and to GOTRA.

-          Press "Calculate" to make the first iteration. The program will warn you to define GPK alignment to either true or magnetic North. Select True North now. The system will use predefined values for OPTIONS, you can change them later.

-          Check all calculated values. Use the column description within the previous chapter to interpret values. There are three main interesting points:

1.      NAS DATA: NAS counters are calculated for the "advanced turn" method, i.e. you have to reset counters at each waypoint. This would be quite difficult, so we will change it to calculate rolled (summarized).

2.      RSBN DATA: On segment BP1-LO we can use RSBN mode FROM. No wonder, the waypoint BP1 is the RSBN station itself. On all other segments we have to use the more general SRP mode as routes do not fit to any RSBN radials. Nothing to do here.

3.      TURN CONTROL: Turn angles are quite large. For smaller angles we might start turning above the waypoints, but for waypoints LO and GOTRA we will define "in-advance" turn.

-          In OPTIONS section change "NAS cntrs" (NAS counters) column to "Rolling" for waypoints LO, ZL, SOLNU and GOTRA. We do not want to bother with the counters there. It will be quite enough to deal with other navigation things. At BP1 we have to reset the counters as that is the first explicit waypoint of our controlled route. D101H dose not matter already as that is the endpoint of our controlled route anyhow.

-          At LO and GOTRA the turn angles are really to big, so set "Turn ctrl" (Turn Control flag) to "In adv" (in advance). We will start turning before reaching the waypoint itself.

-          Press "Calculate" to re-calculate navigation data. See changes.

-          Save the plan on any name by pressing the "Save" button in the WAYPOINTS menu section. In fact this plan is already provided as "UKLI_Navigation_Test.csv" within the package, so if you fail during these initial steps, just load this ready file instead of importing the raw FS flight plan.

-          You might change planned aircraft speed (TAS) for each segment. It is 450 km/h now, but can be changed to any reasonable values. You might want to recalculate again and to save the plan.

We are basically ready with flight planning. Our first controlled waypoint is BP1 which is in fact RSBN station STRY. At the first controlled waypoint we have to reset NAS counters, so we have to know explicitly when we are flying over the waypoint. We might use an NDB, a VOR, an RSBN station or a visually distinguishable location for that.

Hereby we selected the STRY RSBN station as the first controlled waypoint. After take of we have to fly to the RSBN station. We will fly to the station on the same radial that we will have to follow when leaving the station. This way we will not have to make any turn above the waypoint and we will be able to concentrate on initializing the navigation systems.

At the last controlled waypoint (D101H ISEC) we will cross the ILS localizer beam, so we finish NAS/RSBN navigation and use standard ILS approach.

Ground preparations

We have to initialize aircraft equipment and plan for the first controlled waypoint. So let's take the plan with us and sit into the plane.

General preparations

-          Load aircraft at UKLI gate 8 medium

-          Load flight plan "UKLI_Navigation_Test.pln".

-          Open engineer panel and turn avionics switches on ("ПТ-1000" General avionics switch, "АГД-1" Artificial horizon, "ГИК-1" GIK gyroscope, "РСБН" RSBN system, "КУРС-МП" VOR system, "АП-28Л1" Autopilot)

-          Switch to Navigator seat and open-close all other panels from here first for initialization. If you fail to do this, panels might be opened "behind" the main panels and remain invisible.

-          On the GPK sub-panel set geographical latitude of the airport (N49°). The whole route will be within 1° latitude, so we do not have to reset this value during the flight. Turn on GPK system with its main switch. The green airplane of the GPK Indicator will rotate to an arbitrary direction.

-          Open the GPK-GIK high resolution alignment service panel. The red arrow on the bottom scale shows the aircraft heading relative to the GIK gyro, on the upper scale relative to the GPK gyro. Both values are arbitrary at the moment.

-          Align GIK gyroscope to magnetic North by pressing the "fast align" button until the bottom scale (and the big RMI ring) stops moving (remember an induction coil is used here to "scan" Earth magnetic lines of forces). Now the red arrow on the bottom scale shows the aircraft heading relative to magnetic North, i.e. it shows magnetic heading. Form me (FS9, standard scenery, gate 8) it is 356.5°.

-          Because of heavy use of RSBN we will use true headings on our route, so let's align the GPK gyro to true North using the "ЗАДАТЧИК КУРСА" knob. It will move the upper scale. We have to move it until the red arrow (top) points to the true heading. True heading is a sum of magnetic heading and magnetic declination. Check our route plan - magnetic declination at UKLI is 3.6° (load declination values from the Route Planner automatically!), for me true heading is 356.5° + 3.6° = 360.1° = 0.1°. The red arrow should point to this value on the upper scale. While you turn the "ЗАДАТЧИК КУРСА" knob it will display the exact value, so it is really possible to set it accurately (now 0.0° can be set as closest). We will use the airports true meridian as reference meridian. All later directions will be relative to this meridian. Do not re-align GPK gyro any more during the flight!

-          Just to check: the upper scale shows 0.1° (well, 0.0°) true heading, the lower scale shows 356.5° magnetic heading.

Preparation for the first controlled waypoint BP1

We have to know explicitly when we are flying over the first controlled waypoint as the whole NAS system will take its origo from that point. In case RSBN-only navigation we do not have this problem, but here we have to use NAS as well. Hereby we will make a direct RSBN approach, as our first controlled waypoint (BP1) is an RSBN station.

-          We have to leave BP1 towards LO on the 7.0° (true) outbound radial (see "TRUE COURSES" section "Crs >> column" in the plan), so why not to approach BP1 on the 7.0° inbound radial? This way we will not have to turn and we will be able to concentrate on NAS reset. Though the true course will be 7.0°, the course we have to follow on GPK will be 7.7° (see "GPK deg" value in the "GPK & GIK" section) as we already collect 0.7° fork until reaching the radial. Notice that we have to follow the 7.7° GPK course wherever we join the BP1 7.0° radial. That's why we use GPK - it keeps its direction along the orthodrome. GPK always shows the orthodromic course - the angle relative to the reference meridian. RSBN on the other hand uses courses relative to the station, so on PPDA you read azimuth that is independent of your collected fork.

-          On the navigator panel's RSBN sub-panel set channel 11, mode FROM ("ОТ"), Azimuth to 7.0° (Outer ring! No fork here!). Leave Orbita as zero. This is already not trivial, so let's analyze: We are flying on an RSBN radial, so we have to use TO or FROM mode. In FROM mode ZPU = Target Angle, in TO mode ZPU = Target Angle - 180° and in both case it is called Azimuth. In this case azimuth is indefinite, but if we select 7.0° it is equal to our course, so we have to set mode FROM. If we select azimuth as 187°, we have to set mode as TO. I selected mode FROM as in this case only Orbita has to be changed after flying over the waypoint BP1 (mode will remain FROM).

-          If you mix these things (azimuth and mode) you will experience a similar effect than if you would follow a back course, i.e. the VOR/ILS/RSBN track bar will move to the opposite direction on KPPM than what you would expect.

-          The red "no azimuth" and "no distance" signal lamps should be ON, as the RSBN station is not visible while on ground. It will be visible as soon as you climb some hundred meters as the station is not far away. If these lamps are OFF, you had not turn RSBN main switch on at the Engineer panel yet.

-          You can test RSBN equipment by switching to channel 20 (IVANO-FRANKIVSK RSBN). This station is next to you on the airport. Warning lamps should go off and with the current settings (Azimuth and Orbita) the green "target within 15 km" lamp should start blinking. For me PPDA gauge shows that I am 2.1 km far from the station in 76.7° true direction. Do not forget to switch back to channel 11 after test!

-          Select RSBN (this is the default) on the Radio Source Selector sub-panel of the Course-MP panel to receive lateral direction signals on the KPPM gauge. No signal yet (both blinkers are on), but it is not a problem.

-          Set NAS Map Angle to 7.7° as well (you can set 7.75° which is quite fine). We can stabilize our course using the NAS Automatic Coordinator as soon as we capture the 7.0° RSBN radial regardless of any wind.

Other preparations and take-off

Proceed with any other preparations. Check fuel, cargo, every equipment and ask for clearance and start. Taxi to runway 28, set flaps, autopilot to standby and take-off.

Navigation in the air

We have two parallel navigation equipment: RSBN and NAS. The two systems require different approach.

RSBN should be more familiar to those who had used VOR navigation already. The big plus is that you can follow non-radial tracks also using the SRP mode. After setting the RSBN gauges based on data from the Route Planner you use PPDA to check distance (and possible aircraft bearing), RMI to see station bearing and of course KPPM to drive the plane on the track. When close to the next waypoint, you set next segment data on RSBN and you capture the new course using KPPM as you would capture a VOR or ILS radial. Generally you are not flying over the waypoint, you start turning in advance.

In case of NAS navigation you follow the progress on your route based on the coordinate counters especially the Y ("C") counter. For the Y counter to precisely measure route distance, map angle should always be equal to the route segment course angle as shown by GPK. This is the key point of NAS navigation and we will have problems with it during turns. When you decide to start turning - either above the waypoint or in advance - you have to change Map Angle to the new value as fast as possible. Longer immediate Map Angle setting cause bias both in Y counter (where we are along the route?) and in X counter (are we on the track?). Once we initiated our counters by flying over the NAS reference point we have to keep counters switched on during the whole flight. If we fail to do so, our coordinates become void and we have to initialize them over a new "known location".

The whole sample flight can be flown using any of these navigation aids. We will start flying using NAS as main navigation tool, though we will use RSBN to capture the first controlled (reference) waypoint. After waypoint ZOLOCHIV we switch to RSBN and we will not maintain the NAS counters any more. You might fly this sample route several times practicing both methods individually. We will also use NDBs to make life easier during practice.

Approaching the first controlled waypoint

Maintain runway heading (279° magnetic) after take off, or follow ATC directions. You have to follow a track less then 300° to be able to capture the true 7.7° inbound radial of STRY RSBN. Climb and prepare everything, you have more than 10 minutes before reaching the radial.

-          Gears up, flaps back, engage autopilot and let it maintain heading in GPK mode and vario 5-6 m/s (UPRT=81°).

-          Starting with 6 m/s vario you will reach 4 000 m (13 000 feet) altitude before reaching the radial. Level off and engage the "КВ" mode on the autopilot to keep this altitude during the flight. Do not forget to decrease trust when you finish climbing: UPRT=63° will be enough for TAS = 450 km/h (IAS = 365 km/h).

-          Check whether the red "no signal" RSBN warning lights went off . They had to. If not, then RSBN system is not switched on, or you did not select the correct channel (11).

-          Check KPPM. It should also show the signal (upper left blinker is off) and the vertical bar should be on the far left side signing that we are right from the track. If there is no signal on KPPM, then check radio source selector on the Course-MP panel.

-          PPDA shows decreasing distance and bearing from the station. When KPPM vertical bar reaches the middle position, PPDA will show 180° + 7.0° = 187.0° true azimuth. This is in fact a much more precise signal than the KPPM bar.

-          The yellow arrow of the pilot's dual RMI indicator (not default gauge, check Appendix A for configuration) will show RSBN direction if you set the left knob to RSBN. It will reach 7.0° - 3.4° = 3.6° magnetic direction when reaching the radial. Declination is 3.4° here already.

-          We plan the turning to the radial now. We have to turn from magnetic 279° to 3.6° that is more than 80°. We will use GPK Indicator with AP Turn mode to perform the turn. Check that AP is not in Turn mode but in GPK mode. We do not want to start turning right now. We would like to let NAS Automatic Control to finalize the turn and align the plane with the bearing. For that we have to be sure that we cross the bearing, so we will be cautious not to turn over before reaching it. Set something like 350° on GPK Turn Indicator instead of 7.7°.  AP will turn the plane, but it will still cross the bearing by some 17°.

-          When KPPM vertical bar starts moving in the middle, check PPDA azimuth. When it reaches 180° (see thin needle for precise value) we start turning right by switching AP to  Turn ("ЗК") mode.

-          When crossing the radial (see KPPM and PPDA azimuth) switch NAS Automatic Control (left button on Lateral Deviation gauge) on. We will overrun, but NAS AC will drive the plane back to the track and will maintain 7.7° course (set as Map Angle) based on GPK. During my tests I had a 22 knots crosswind from 270° causing a +6° (right) slip, but AC compensated it automatically.

-          Switch AP mode from Turn to GPK, otherwise if you turn Automatic Control off, AP will turn the plane back to the heading defined on GPK Turn Indicator. It is always a good practice not to leave AP mode on Turn if not necessary.

-          Check Azimuth on PPDA: if it is larger then 7.7° then you are a bit left to the desired track, if less, you are right. It is OK until NAS is correcting the track, but once it is stabilized this signs a small bias. If even KPPM shows the deviation than it is possibly too big. You might make corrections, but you do not have too much time.

Capturing the fly-over moment

Now we have to concentrate on when we fly over the station (our first controlled waypoint) as this will be the NAS reference coordinate point (we have not turned NAS counters yet). The green "target within 15 km" starts blinking 15 km in advance, but the red "target within 1 km" lamp will never go on, as we will not get closer to the station as about 3.6 km (AGL = altitude - elevation), we will fly over it. In fact the PPDA distance counter will also show more and more biased values as we will reach the station. It will count slower and slower and at about 3,7 km it will stop. It is measuring on a direct line and not on the surface (map). Here are two tricks to calculate the fly-over moment:

-          First trick: Right above the station in a conical area RSBN receiver will lose azimuth signal and the red "no azimuth signal" warning lamp will come up. At this height flying by approximately 450 km/h TAS we reach the centre of the cone (the station) within 5 seconds after we lose the signal. Check the lamp and when it turns on, count from zero to five. At five you are above the station.

-          Second trick: Let's use a counter that measures distance independently of RSBN. It is NAS. Map angle is set to our course so if we turn NAS counters on Y ("C") coordinate will count distance we fly on our course. Let's start counting at 10 km before the station: set high resolution Y ("C") counter to 90 km (that is -10 km). We know that we will fly 4 000 - 300 = 3 700 m over the station (elevation at the station is 300 m). From the station 3.7 km up and then 10.0 km horizontally - that is the point where we have to start counting. And these are the perpendicular sides of a triangle, the third side being the line (distance) measured by RSBN from the airplane directly to the station. It can be calculated based on the famous c2 = a2 + b2 equation of Pythagoras…

When we see 10.7 km on the PPDA we are in fact 10.0 km far from the station in horizontal direction. At this moment we switch on NAS counters and when we see high resolution counter reaching zero, we are right above the station.

Figure 29 - Determining fly-over by timer and by NAS

-          The timer method is simple, but it depends on speed and height. The NAS method is a bit more complex, but accurate and additionally we already start counters and Y counter by definition will reach zero when we fly over the station, so we just have to sit and wait; nothing urgent to do above the waypoint. All-in-all, I recommend the NAS counter method. Let's take a paper and pen (and a calculator) and calculate the trigger RSBN distance if you have other values than what we have in the example.

-          We have done! If you had selected the timer method, you have to switch on NAS counters at the fly-over moment. If you used NAS counters, you do not have to do anything urgent. Just see how the red "no azimuth signal" goes off and how PPDA and KPPM go live as soon as you leave the "dead" area above the station.

The BP1 - LO segment

Check "SEGMENT" data in the plan - we have 9 minutes until reaching LO NDB. We use NAS as main navigation equipment, but we might check our track on the KPPM as well. At the next waypoint we have to make a 86° right turn. Quite big one - we will not fly over waypoint LO, but we will start the turn in-advance as we planned.

-          RSBN channel, mode and Azimuth remain the same, but we have to set Orbita to our turning point. It is 63.4 km based on our plan. Warning lamps will sign 15 km and 1 km distance from that point.

-          Set LO NDB frequency (315.0 kHz) on the second set and switch the dual RMI to show it with the thick white needle. The yellow one still shows the RSBN behind us. Be careful! LO is acting as an outer marker for a nearby airport (UKLL - L'viv), though it is a large distance NDB as well. As it happens in this region regularly there are two NDBs with the same frequency at different end of the runway. They transmit different Morse code however, and as they say in real life only one of them is active at a time. Anyhow in FS both NDBs are active and you will capture the nearest one always. This is the bad one for us during the first part of the route segment, so do not rely on it. If it is not odd enough I have to mention that in FS Navigator only one of them is visible, so it is really extremely confusing. In FS Map both is visible correctly. Anyhow, we are not using the NDB for navigation, so it does not really matter…

-          As Automatic Control is managing the plane, X coordinate should be rather stable zero (no deviance). When near to the turning point you might preset the new segment's initial X value on the high resolution X (B) gauge. It is 4.0 km based on the "B >>" column of the "NAS DATA" section in the plan. It means that after we start the turn and change NAS to the new Map Angle, we will be 4.0 km right (positive) from the new track. That is OK - by the end of the turn we will be hopefully right on the track, thus X counter will reach zero. If we do not preset the counter here, then by the end of the turn (when we reach the new track) X will show -4.0 km. That is OK; after stabilizing on the track, you might reset the counter (to zero).

-          Check high resolution Y counter. When it reaches 63.36 km, then you had reached the turning point. You might check RSBN PPDA distance counter also. At 15 and 1 km before the point you will get warning from RSBN. Well, the two methods (NAS Y counter and RSBN) might of course sign turning point differently because of various biases. If any radiometric distance information is available (for example RSBN), then is it preferred over the inertial NAS system.

-          At the turn point you have to change Map Angle fast to the new value. This is a critical operation. While Map Angle is not equal to the new value it is not calculating Y and X coordinates correctly. Your strategy should be to change roughly to the new angle fast and then make smooth corrections to adjust precisely. Remember that clicking on the outer region of the gauge will change fast by 5°, clicking on the inner region will change by 0.25°.

-          If you leave Automatic Control performing the turn this way, it will assume that the new segment starts at the point where you had modified Map Angle. Deviation control (small airplane) starts showing increasing negative values, as it assumes that we have turned above the waypoint, and we are overrunning. If we leave this in this way it will overturn and return back to the line that goes through the turn start point and parallel to our desired track. We have to let AC know about the lateral deviation of the turn point from the desired track. It is +4.0 km as we picked up before, so let's set this on the Deviation Control gauge. In real life setting the new Map Angle and setting the known lateral deviation happens fast - nearly at the same time. However in FS we might not be fast enough with the mouse, so by the time we start setting lateral deviation it is already starts moving to negative direction. If we concentrate on to set it to +4.0 km we might set false value. Anyhow we know that clicking once on the right side of the deviation setting knob we increase the value by 500 m. So just click eight times (8 x 0.5 = 4.0) and whatever is the actual value shown, you defined that the deviation differs by 4.0 km from what AC assumes.

It is important to understand that changing the X counter to the segment's initial value (as we optionally did in the previous step) is not effecting Automatic Control behavior. It is just a counter that in fact you can modify any time. If counter switch is turned on NAS modifying its value based on Map Angle and on the movement of the plane, but it is not effecting the control of the plane. When Automatic Control is on it is displaying known deviation on the Deviation Control gauge. These things work independently, the only loose relation is being the Map Angle.

This might seem to be a lot to do, but in fact we just had to wait until we reached the turning point, and there we had to set new map angle and lateral deviation. That's it.

The LO - ZL segment

If you made everything correctly Automatic Control should precisely turn the plane to the new track. Deviation should disappear (becomes zero). At the end of this segment at ZL we have to make a 53° turn. It is still quite big, but we will try the simple turn method - starting the turn above the waypoint.

-          Check high resolution X. If it is stabilizing, you are on the track. X counter should be zero if you preset the value to +4.0 km, otherwise it is -4.0 km. You can reset X counter to show 0.

-          Check Y counter. We did not reset it at the starting moment of the turn. It is not a problem, we have calculated all Y counter values cumulative (rolled). Do not be confused by that - the value here does not show the distance from the starting point of the actual segment.

-          You might set RSBN to show new segment data at this point. You have to do this if you are using RSBN as the main navigation tool, but now it is optional. This segment does not fit to any RSBN radials, so we have to set mode to SRP. Check "RSBN DATA" in the plan: ZPU = 93.5°, Target Angle = 52.1°, Target Distance = 101.5 km. Azimuth and Orbita are just used for the 15 and 1 km warning signals in SRP mode, so it is not urgent to set them yet. Anyhow Azimuth = Target Angle, Orbita = Target Distance.

-          You might also set the frequency of the Zolochiv NDB (265.0 MHz, ZL).

-          Check high resolution Y counter. When it shows 135.57 km (cumulative value!), you have reached ZL. We are not turning in advance, so it is ZL itself. You might also use RSBN signals to determine the fly-over moment. After the red "Target within 1 km" lamp comes up it will take 8 seconds to reach the waypoint with this speed (450 km/h).

-          Above the waypoint change Map Angle fast to the new angle 147.3° and Automatic Control will perform the turn. It will overrun the segment, but will return to it automatically.

The ZL - SOLNU segment

For didactical purposes from this waypoint we will switch to RSBN navigation and we will use NAS only to stabilize the track via Automatic Control. When using RSBN we could have two main goals: 1/ flying over the waypoints precisely, or 2/ flying the segments precisely. We will not bother with waypoints too precisely, will concentrate on the second goal. As soon as the green "Target within 15 km" warning comes up, we change RSBN settings for the new segment and turn to it based on KPPM as we would turn onto a VOR radial.

-          Already during the automatic turn over ZL you can start programming RSBN for this segment: channel (11) and mode (SRP) is still the same; ZPU=146.6°, Target Angle=86.7° and Target Distance=117.0km. Set Azimuth and Orbita also to trigger the distance warning.

-          We do not need NAS coordinates any more during this test. You might leave them running, but you might switch them off also. We will rely on the green RSBN warning lamp to determine the closing waypoint, but we are not very much interested on the precise figures. However we will still use NAS Automatic Control to drive the plane along the tracks.

-          Turn angle at SOLNU will be 13°. Not too much - we can fly over the waypoint and let NAS Automatic Control to turn the plane to the new track.

-          When the green "Target within 15 km" warning comes up we have 15 * 8 = 120 seconds until the waypoint.

-          Change RSBN settings for the new segment: Channel=20 (this is Ivano-Frankovsk RSBN already), mode=SRP, ZPU=160.5°, Target Angle=82.4° and Target Distance=65.4km. You should see the closing track on KPPM from the left. Set Azimuth and Orbita also though you can do this after the turn if you do not have time.

-          Check whether AP is in GPK mode and turn NAS Automatic Control off.

-          Change Map Angle for the new segment: 160.5°. You do not have to be very fast now, Automatic Control is off, so the plane will not start turning.

-          Check KPPM and when the vertical tracking bar is in the middle (you are crossing the new track), turn NAS Automatic Control on again. AC will turn the plane and correct the small overrun. KPPM tracking bar should be stabilized in the middle regardless of any cross wind.

The SOLNU - GOTRA segment

The main difference here is that at the end of this segment at GOTRA we have to make a big turn of 102°. If we would let AC to make this turn starting over GOTRA, the overrun would be too big. Instead we will turn in advance using GPK Indicator and AP Turn Mode as we did before our first waypoint BP1 and we will let Automatic Control to finalize the turn and to stabilize on the next track.

-          Check whether AP is in GPK mode and set turn destination course GPK Indicator. The final orthodromic course is 262.6°, but we again would like to cross the new track with a solid angle, so set some 245° to cross the track by some 18°.

-          When the green "Target within 15 km" warning comes up we have two minutes until we reach the turn point. In the Route Planner we asked for "In advance" turn so it calculated Azimuth and Orbita for the turning point instead of the waypoint itself.

-          Change RSBN settings for the new segment: Channel (20) and mode (SRP) is the same, ZPU=262.6°, Target Angle=104.1° and Target Distance=14.3km. You should again see the closing track on KPPM from the left. Do not modify Azimuth and Orbita yet. They are still pointing to the turning point at GOTRA and as we did not modify the RSBN channel (station) they are still valid and will warn us when "Target is within 1km", the target being the turning point.

-          Turn Automatic control off and change Map Angle for the new segment: 262.6°.

-          When the red "Target is within 1km" lamp comes up, count to eight and then switch Autopilot to Turn mode. AP will start turning the plane.

-          Check KPPM and when the vertical tracking bar is in the middle (you are crossing the new track), turn NAS Automatic Control on again. AC will correct the small overrun. KPPM tracking bar should be stabilized in the middle regardless of any cross wind.

-          Turn AP to GPK mode to avoid unintentional turn later.

The GOTRA - D101H segment

This is our final controlled segment. We have to start descending and at end we have to capture the ILS of runway 28.

-          Start descend right after the turn by 9 m/s. Keep TAS around 420 km/h (UPRT=25°).

-          Set Azimuth and Orbita. This will warn as for the closing last waypoint.

-          Set ILS frequency 109.3 MHz on the first VOR block of Course-MP panel.

-          At altitude 800m bring the plane to level flight with the AP. Increase power as needed. You might open some flaps already.

-          The ILS magnetic course is 279°, the orthodromic course is 283.1° (see "GPK deg" in the "GPK & GIK" section). The turn is 21°. We might cross D101H and let NAS Automatic Control to perform the turn and stabilize on the final. This is the same procedure we used at SOLNU with the only difference that here we turn onto an ILS course.

-          When the green "Target within 15 km" warning comes up switch Radio Source Selector on the Course-MP panel from RSBN to 1 to receive the ILS signal on KPPM (ILS frequency is already set). You should see the closing track on KPPM from the left. You will also see the tracking bar of the vertical beam. Most probably you are already below the glide slope.

-          Check whether AP is in GPK mode and turn NAS Automatic Control off.

-          Change Map Angle for the last segment: 283.1°.

-          You might open more flaps and release the gears. Most probably more power is needed. To keep speed above 250 km/h

-          Check KPPM and when the vertical tracking bar is in the middle (you are crossing the new track), turn NAS Automatic Control on again. AC will turn the plane and correct the small overrun.

The final on runway 28

-          You will reach the glide slope from below rather fast, it is not a long final. Set landing flap configuration and set 3 m/sec descent.

-          Check lights, gear and report that you are on ILS.

-          There is no DME attached to the ILS so do not expect distance data. On PPDA you still see distance from Ivano-Frankovsk RSBN on the airport, but that is some 1.5 km behind the runway landing zone.

-          Even if you made the final turn precisely with Automatic Control, it will not bring you down automatically. Turn AGL meter on to keep track of height above ground. At around 400 m AGL turn autopilot off and land the aircraft manually.

The Navigator Notepad

The Navigator Notepad is a panel for AN24/26 that reads prepared route segment data from file and loads it to the NAS and RSBN systems automatically triggered by a single button press when flying over the waypoint. In automatic navigation mode it drives the plane from the first controlled waypoint automatically.

Figure 30 - The Navigator Notepad panel in front of the RSBN gauges.

Navigator Notepad can be opened/closed by pressing Shift-5. Its input file is read from the <FS9 folder>\Aircrafts\An-24RV\utils\RoutePlanner\data\*.dat files exported from the Route Planner.

Description of the Navigator Notepad screen is as follows…






The 5th segment of the route



Previous and next route segment



Previous and next route file in directory <FS9>\an24_calculator\



Beginning and ending waypoint of actual route segment. Here ZL is an NDB, SOLNU is an ISEC point.

When selecting a route file, the route file name appears here with red letters for 3-4 seconds.

Map angle

147.3 °

NAS map angle


1.5 / -1.1 km

NAS X (B) and Y (C) starting coordinates at the route's beginning point. It is 0/0 if turning starts at the waypoint. In this case turn starts before ZL NDB, thus starting X coordinate will be 1.5 km, Y coordinate -1.1 km.


66.7 km

Length of route segment as measured by the NAS Y (C) counter. When The NAS Y counter reaches this value turning to the next segment should be started and NAS values should be changed to the new segment.

RSBN mode


RSBN work mode for this route segment. Here it is SRP.



RSBN channel, here 11 for RSBN STRY


146.5 °

RSBN ZPU degree if RSBN mode is SRP. Otherwise it is empty.


86.6 °

RSBN azimuth degree or  target angle.


116.9 km

RSBN orbita or target distance.



Feeds NAS data on page to the NAS equipment.



Feeds RSBN data on the page to the RSBN equipment.



Feeds both NAS and RSBN data on page to the corresponding equipment.



Switch automatic navigation mode ON/OFF. When turning ON, it also turns NAS Automatic Control and NAS coordinate counter switch on.

To turn NAS Automatic Control and counter switch on without turning automatic navigation on, press the button twice. It will turn automatic navigation On and OFF, but leaving the other two functions ON.

ATTENTION: Autopilot itself should be ON when switching to Automatic Navigation mode. This is not checked by the system.


Preparing a route data file

Navigator Notepad reads NAS and RSBN navigation data from an ASCII file exported from Route Planner. The general steps creating the file are as follows (detailed information can be read in the chapter about Route Planner):

-          Create a flight plan in MS Flight Simulator and save it.

-          You might create the plan in FS Navigator, but that should be exported as FS2004 flight plan.

-          Open Route Planner and import the saved file by pressing the Import button and selecting the file in the Open File dialog box. Waypoints will be read with names and coordinates and magnetic declination will be read from FS.

-          Define all options and RSBN station information and calculate navigation info.

For working with the Navigator Notepad you have to make some special considerations. These generally relates to the fact that the Navigator Notepad will load navigation data to the equipment by a keystroke, so you do not have to make most of the tricks described in earlier chapters.

-          You can set NAS counters column to "Reset" and you can use Turn Control "In advance".

-          For the waypoint where you would like to turn Automatic Navigation (autofeed) option on, you should define Turn Control "Waypoint".

-          Set GPK alignment (either to True or Magnetic North) only on first waypoint (generally on ground). If you are not using Automatic Navigation, you can set GPK at other waypoints also, but it will not work with Automatic Navigation.

-          Save the plan and also export it by pressing the Export button to the <FS9 folder>\Aircrafts\An-24RV\utils\RoutePlanner\data directory from where it will be loaded by Navigator Notepad.

Using Navigator Notepad during flight

During flight preparation open Navigator Notepad by pressing Shift-5 or by selecting it from the Views/Instrument Panel menu and perform the next steps:

-          Navigator Notepad will automatically load the first file found in the directory. If it is not the one you would like to use, press the down and up arrows (65) to select your file. The file name will appear for 2-3 seconds on the 2nd line in read.

-          Select the first route segment you are interested in by pressing the previous and next arrows (34).  The segment staring and ending waypoints will be displayed on the 2nd line.

-          Feed NAS, RSBN data or both to the navigation equipment with the buttons at the bottom of the panel.

-          Align GIK and GPK gyros depending on the settings you had defined when you had created the plan. 

The first route segment might be right from the end of the runway to the first waypoint. NAS could not be used here, as it can only be used some hundred meters above the ground, so it has to be reset somewhere in air above a known position. However RSBN can be used and it could be quite useful to drive us to the first waypoint where we can initialize NAS. We will also use Automatic navigation mode. Considering this scenario follow the next steps:

-          After take-off disregard NAS data and drive the plane based on RSBN information. If no RSBN information, use any other navigation method to drive the plane to the first waypoint where you can initialize NAS.

-          Engage autopilot and switch it to GPK mode. It is very important to switch autopilot on before switching Automatic Navigation on. Automatic navigation is based on NAS Automatic Control and that is based on autopilot.

-          Check for the first controlled waypoint. Use any visual target, or RSBN, VOR or NDB information. If you are using RSBN then guide the plane along the defined route and check distance on PPDA. The RSBN warning lamps will sign 15 and 1 km distance from the waypoint.

-          Open Navigator Panel, step to the next segment by the 4 button and load NAS data to the NAS equipment by clicking the NAS button. If you are using RSBN to detect reaching the waypoint, you must NOT load RSBN data because you are still using RSBN settings for the present route segment.

-          When reaching the waypoint, press the Auto button to turn on Automatic Navigation mode. This will also turn on NAS counter switch and NAS Automatic Control. The plane will perform a turn to the next segment and will correct overrun.

-          You can load RSBN data now by pressing RSBN button.

-          From this point on Automatic Navigation will drive the plane to the last segment.

You have to understand that Navigator Notepad is primarily a help only to load prepared navigation data to NAS and/or RSBN.

Automatic navigation (AN)  is an extra feature that is based on NAS only! You can freely modify RSBN settings, it will not effect Automatic Navigation. AN is using an extra information for switching to the new route segment: the calculated length of the segment keeping in mind in-advance turns. It is also calculated by the Route Planner and is used by the navigator when not using Navigator Notepad. When NAS "Y" ("C") counter reaches segment length, turn should be started and navigation equipment (NAS and RSBN) should be set to the next segment. As AN is independent of RSBN, it can be used at any part of the World (in fact only on the Northern hemisphere due to GPK gyro limitations - see details there).

As NAS is an inertial system, it sums up errors and time-by-time the route should be corrected based on external information (mostly VOR or RSBN data). The present version of Navigator Notepad does not fully support on-the-fly corrections, thought a lot of manual things can be done.

The limitation is that you can not easily enter correction data when Automatic Navigation mode is on. If - based on external information - you experience a lateral deviation (NAS X coordinate) you can set it on the Lateral Deviation (ЛБУ) gauge. The only limitation is that you must be sure that the deviation could be corrected by Automatic Control before reaching the next turn point. Deviation on the Y counter however can not be entered into the system. It practically means the correction of the Y counter and it can not be done easily. There is one possibility only: to deduct the difference from the calculated route segment length, switch Automatic Navigation off and start the next segment (by loading next segment NAS data) manually with the NAS (or BOTH) button when reaching the modified route segment length value on the NAS Y counter.

Navigator Notepad input file

The structure of this file is subject of change at any release. The structure of the current version is described in the Appendix.

Sample flight around Boryspol airport (UKBB, Kiev)

A 265 nm long (1h 15m) sample flight is prepared around Kiev's Borispol airport:




MS Flight Simulator flight plan. Exported from FS Navigator in FS2004 format.


Route Planner flight plan with RSBN data and with other options defined


Navigator notepad route file


GPK is aligned to GIK on the ground. Take-off runway is 36R, the first route segment start point is the opposite end of the runway i.e. 18L. End of first segment and reference point of NAS navigation is BOHDANIVKA NDB (BO). This NDB can not be tuned in FS as its frequency is 1290.0 KHz.

-          Before take-off load the file to Navigator Notepad. Check that the 1st segment is "UKBB - BO" and feed RSBN data to RSBN equipment. NAS is not initialized yet.

-          Select the next (2nd) segment "BO - Fix01" and feed NAS only! RSBN values for that segment will be loaded after turning to that segment.

-          Take-off and follow the route based on RSBN (slight left turn).

-          Turn autopilot on and set GPK mode. Stabilize the pane on the RSBN defined route.

-          Check PPDA distance. Target Distance (Orbita) is 32.4 km. When PPDA shows this value - and if you are on the RSBN track - you had reached BOHDANIVKA NDB. The RSBN warning lights will also sign when within 1 km from the target.

-          At the waypoint click on Navigator Notepad AUTO button to turn Automatic Navigation on. Remember that we had already turned autopilot on and we had already fed NAS with 2nd segment NAS data (but not with RSBN data).

-          The plane starts turning left and corrects overrun (we started the turn above the waypoint as it generally happens at the first controlled waypoint) if everything is OK.

-          Feed current RSBN data by clicking on the RSBN button.

-          From now on up to the landing 36R Automatic Navigator will automatically read and feed segment navigation data and will perform navigation based on NAS Automatic Control.

You will see that time-by-time we will fly "beside" the route defined by RSBN, but the overall bias will not be more than 1 km by the end of the 75 minute flight. You might try a second run and adjust the track around the middle of the segments by Lateral Deviation control based on RSBN information. You do not have to make difficult calculations, just estimate the distance from the track based on KPPM data and set the value on NAS Lateral Deviation gauge.

The Navigator Passanger and fuel loader

A simple but useful An-24RV passanger and fuel loader is added. During launch select the An24 aircraft.cfg file in the popped up dialog box. The program should be used before loading the aircraft into FS. Usage of the program is rather straightforward.

Appendix 1 - Configuration tips

Windows regional settings


Author: Gabor Hrasko

Added: 18.06.2004


For some there are some strange problems:


-          Though autopilot generally works, the "up-down" switches do not modify the pitch of the plane.

-          RSBN channels can not be set (RSBN does not work)


Related parameters are defined in:



The file contains numbers with decimal digits. It uses '.' (decimal dot) while some

Windows regional settings (Hungarian for example) expect decimals separated by ',' (decimal comma) instead. The result is that the configuration data is read incorrectly by the gauges. You have two options:


-          Modify Windows regional settings to use '.' instead of ',' to sign decimals (PREFERRED SOLUTION)

-          Modify the stt_navgau.cfg file to contain ',' instead of '.' to sign decimals


RSBN scenery (for FS2004 only!)


Site: files section


Size: 47 K

Added: 01.03.2004

Authors: Андрей Прядко


This pack includes two sceneries of RSBN Navaids for use with appropriate onboard equipment of aicrafts made by Stepan Gritsevsky ( IL-18, Tu-154, An-24RV,...), and ONLY for their FS2004 versions.


-          CIS_RSBN Scenery includes 108 stations and covers the whole territory of Russia/CIS contries according to real navigation data of end 2002.

-          USSR_RSBN Scenery includes 197 RSBN stations and covers the territory of USSR ( navigation data - late 1980s) Localities names are of that epoch.


Install only one of the two packages! I recommend using CIS_RSBN for realistic flying in present times. If you use FSNavigator, dont' forget to update it's database via



RSBN scenery (for FS2002 only!)


Site: files section


Size: 7 443 K

Added: 07.04.2003 21:04

Authors: Валерий Бочарников


This is a complete FS2002 AN-24 panel, but it includes an FS2002 compatible RSBN

scenery package from Андрея Прядко. Install only from the RSBN directory! If you use FSNavigator, dont' forget to update it's database via FSNavDBC.exe.


Appendix 2 - Navigation Notepad input file structure

The structure of this file is subject of change at any release. Presently the structure is the following:


354.33,0,0,0,31482,40,5,16,324,3595,16,324,"UKBB - BO"

310.38,0,0,0,30311,40,5,3394,577,3156,3394,577,"BO - Fix01"

217.69,164,-3500,-3500,34209,40,5,3044,557,2229,3044,557,"Fix01 - UKKM"


Fields are as follows (see segment 3 for example):



This file can be edited or assembled manually if one fully understands the meaning of the values here.