F-4B/N Navigation equipment
Data used for the aircraft's navigation systems is relayed from:
- Forward cockpit
- Attitude-direction indicator
- Horizontal situation indicator
- True airspeed indicator
- Compass control panel
- Navigation radio
- Rear cockpit
- Navigation radio
- ASN-39 Inertial navigation system
Compass control panel
The compass control panel allows the pilot to select the source of heading signals for the HSI and ADI. Available modes are:
- SLAVE, COMP: simulated the same way, these modes output magnetic aircraft heading on the HSI and ADI
- FREE: this mode requires the pilot to input current aircraft latitude and magnetic variation to the compass system. First, input the current latitude using the latitude knob on the right. To synchronise magnetic variation, turn the knob labeled PUSH TO TURN in the direction of the SYN IND needle, until it is centered. This mode produces increasing error as the difference of actual vs set latitude increases, so it is required that the aircraft latitude is constantly updated.
The INS calculates the current aircraft position using dead reckoning calculations. It requires inputs of current aircraft position, magnetic variation, wind speed and direction. This information is combined with true airspeed and magnetic heading information from the air data computer to provide an estimate of the current position. The INS can be set up using the ACM or the physical INS in the rear cockpit.
Physical INS setup
- Rotate the power knob (#1) to STBY
- Input wind speed
- Input the direction from which the wind is blowing
- Input the local magnetic variation. You can see the value from the ACM or from magnetic variation maps
- Input the aircraft's current latitude/longitude using the knobs
- Use left/right and the mousewheel on the knobs labeled 5 to change the values
- Click with your mousewheel to change the increment values. The knobs increment values by 1 degree by default. Wheel-clicking on the knob will change the increment to 0.1 degrees. Wheel-clicking again will swap it back to 1 degree increments.
- Ensure that you have remained in STBY for 60 seconds to allow the INS to align
- Above 150 knots true air speed, rotate the power knob to TARGET or BASE to activate the INS
To set TARGET coordinates, you need to be in TARGET or STBY mode. Using the knobs labeled 6, set the target steerpoint coordinates.
To set the BASE coordinates, you need to be in RESET mode. Use the knobs labeled 5 to input the return/alternate airport coordinates. Rotate the power knob to BASE to provide steering information to the BASE waypoint. NOTE: When in RESET mode, these knobs set BASE coordinates, not AIRCRAFT as described above! BASE coordinates can only be changed in RESET mode!
ACM INS setup
The ACM can help you set up the INS quickly, by providing an easier interface than the real instrument and providing information such as magnetic variation and wind speed. Furthermore, the INS allows you to save and load settings so that you don't have to input them every single time. Please refer to the ACM chapter for details.
Navigation modes are controlled using the navigation function selector panel, which controls what information is relayed to the pilot's ADI and HSI.
The Bearing/Distance switch on the left controls the DME and bearing pointer on the HSI and has three settings:
- TACAN: The bearing pointer indicates magnetic bearing to the selected TACAN station. The DME indicates distance to the station, if the navigation radio is set to T/R. In this mode, the TAC light is illuminated on the HSI.
- ADF: INOP. The UHF light is illuminated on the HSI.
- NAV COMP: The bearing pointer indicates magnetic bearing to the TARGET or BASE steerpoint, depending on INS setting. The DME indicates the distance in nautical miles. If the distance is greater than 300nm, the DME window indicates 300nm. In this mode, the NAV light is illuminated on the HSI.
The mode selector knob on the right controls the pitch and bank steering bars on the ADI, the heading bug and course arrow on the HSI.
- ATT (attitude)
- When the AFCS is engaged and this mode is selected, the autopilot will try to trim the aircraft to maintain the current pitch and bank attitude as soon as the stick is centered in the respective axis. If the stick is centered within five degrees of bank from level flight, the AFCS will automatically bring the plane to a wings-level attitude. This feature can be toggled using the TAILWHEEL LOCK key command.
- HSI: the course arrow, course deviation indicator and heading marker are slaved to the magnetic heading of the airplane. No mode light is illuminated.
- ADI: All pointers are deflected out of view. Only Attitude and azimuth are displayed
- HDG (Heading): When the AFCS is engaged and wing leveler is active, the autopilot will turn to intercept the selected heading on the HSI.
- HSI: The heading marker is positioned by the heading set knob to provide the ADI bank steering bar with bank and azimuth information. The MAN mode light is illuminated.
- ADI: The bank steering bar indicates bank angle steering up to 30 degrees to approach the selected heading.
- HSI: The course deviation indicator is placed to the desired radial using the course knob.
- ADI: The bank steering bar indicates the bank angle to intercept the TACAN radial. When on the radial and wings level, the bank steering bar should be centered.
- NAV COMP
- HSI: The heading marker indicates the heading to the selected steerpoint, BASE or TARGET. The course deviation indicator indicates bearing to the selected steer point.
- ADI: The bank steering bar indicates bank angle steering up to 30 degrees to intercept the heading towards the steerpoint.
The RIO has a suite of basic flight and navigation instruments to aid him in navigation. The main navigation instruments are the INS described above and the bearing, distance and heading indicator, consisting of:
- a rotating compass drum, indicating magnetic heading
- two dme drums in the center
- two rotating needles. The arrow-shaped needle is No.1, while the B shaped needle is No.2
The two needles are controlled by the NAV COMP switch on the rear cockpit's lighting and compass control panel. The BDHI needle options are:
- Early F-4B aircraft (BDHI switch):
- Up: BDHI needle No.1 will indicate bearing to the selected ADF station and No.2 bearing to the selected TACAN station
- Down: Relays TARGET or BASE coordinates to the BDHI, depending on INS setting. Needle No.1 will indicate bearing and No.2 will indicate track to the selected waypoint.
- On Late F-4B and F-4N aircraft (BDHI knob):
- Left: BDHI needle No.1 will indicate bearing to the selected ADF station and No.2 bearing to the selected TACAN station
- Middle: Not simulated
- Right: Relays TARGET or BASE coordinates to the BDHI, depending on INS setting. Needle No.1 will indicate bearing and No.2 will indicate track to the selected waypoint.