A/C with the #1 Radio Altimeter display failing on Primary Flight Display. Indication was not "XXX" as with a failed R/T.
My explanation of how a Radio Alt works in the vid was weak. In a nutshell, the system uses "timing" of the transmitted signal until it is received back at the R/T. The longer the time between send and receive the higher you are. Radio Altimeter signals are only used from the 0-2500 foot range (above the actual ground, it is not dependent on baro altitude). Radio Altitude height is not only used by the crew for a visual indication, it is used by the FCC's for auto-flight, and the GPWS for almost all the Ground Proximity calculations.
Cable length of the transmit and receive co-ax's is critical. Without looking it up, I think most, if not all manufacturers require a cable to be replaced instead of repaired.
