• Radio Altitude (RA) No Computed Data (NCD): Notes:
  • RA NCD data causes the RA display and rising runway symbol to be removed and also the flight directors could bias out of view with a PSEU light illuminated on the ground. The NCD occurs when the return RA signals are too weak or the radio altitude is more than 2500 feet. Also, the rising runway will not show when the ILS is not captured.
  
  
  RA NCD Causes:

  Before replacing any component perform BITE if available. (R/A R/T bite check in main E&E)

  
  

  1.RA Receiver/Transmitter.

  
  

  2.Receive Antenna.

  
  

  3.Transmit Antenna

  
  

  4.Wiring from the Antennas to the RA Receiver/Transmitter.

  
  

  5.Aircraft is 2500 feet or more above the ground.

  
  
  Radio Altitude (RA) No Computed Data (NCD):

  

  
  

  

  
  Circuit Breakers:

  R/A #1: P18-1 = B2.

  R/A#2: P6-1 = A16.

  DEU#1 HOLD UP: P6-1 = D10.

  DEU#1 PRIMARY: P18-2 = D5.

  DEU#2 HOLD UP: P6-1 = D9.

  DEU#2 PRIMARY: P6-1 = D11.

  
  
  Applicable deferrals MEL 34-20 Radio Altimeter System
  

Training Only