• OFF Flag In-view (Rising runway function on ADI operates normally):

  1.Replace indicator.
  
  2.Check for power to the indicator.
  
  3.Check wiring from R/T unit to indicator.

  
  OFF Flag In-view (Rising runway function on ADI does not work):

  1.Replace R/T unit.

  
  
  2.Check power to R/T unit.
  
  
  3.Check wiring from R/T unit to indicators.
  
  
  4.Check coax from rack to antennas.
  
  
  5.Check condition of antennas.
  
  T/S R/A system From Flt Deck With Enhanced GPWS System:

  If you can’t capture the localizer and bring the runway symbol into-view then do the following to determine whether its the indicator or source (R/T) causing the flag. Must have EGPWS.

  
  

  1.Pull circuit breaker for the Operative Radio Altimeter system.

  
  
  2.Observe the "INOP" light on the Gnd Prox warn control panel (lower P3).
  
  
  3.If the Gnd Prox "INOP" light illuminates when you pull the opertive Radio Altimeter C/B then the opposite (flagged) R/T unit is failed.
  
  
  4.If the Gnd Prox "INOP" light does not illuminate when you pull the opertive radio altimeter C/B, then the opposite (flagged) Radio Altimeter indicator is the problem.
  
  

  The Enhanced Ground Prox computer receives inputs from both radio altimeter R/T’s. If both fail then the inop light will illuminate. By pulling one of the radio altimeter C/B’s you are simulating a dual failure if the opposite R/T unit is already failed. You can also check for a valid RA signal if your aircaft has a HUD system.

  
  RADIO ALTIMETER INFORMATION:

  

  
  Circuit Breakers:

  Radio Altimeter #1: P18-1 = B4.

  Radio Altimeter #2: P6-1 = A16.

  
  Notes:

  The radio altimeter indicators are the week link in this system. When a flag comes into view on the radio altimeter indicator,using the rising runway symbol on the corresponding ADI is the quick and easy way to distinguish what is causing the flag as indicated above. On the ground, in order to get the rising runway to come into-view on the ADI, you must tune an active ILS frequency at your airport, and, be able to receive a valid localizer signal. This may not be possible depending on where the aircraft is located in relation to the runway and localizer transmiter that you have tuned.

  
  Applicable deferrals 34-20=Radio Altimeter System.
  34-43=Radio Height Alert (Decision Height).

Training Only