Radio Altimeter Flashcards
What systems using radio altimeter
Autopilot / throttle
Ground proximity warning system
TCAS
How does a radio altimeter work
Uses radio waves to detect distance between aircraft and surface
What height does a radio altimeter work
Always working but doesn’t display height above 2500ft
What is the frequency of radio altimeter
4300 MHZ +/- 50 MHZ
“Continuous wave frequency modulated”
(CWFM)
What frequency band is radio altimeter
Super high frequency (centimetic)
What is the relationship between frequency different and height above surface for radio altimeter
Frequency difference is directly proportional to height above surface
Where is the radio altimeter datum
Main gear
What is cable length compensation (radio altimeter)
Removal of error from radio altimeter datum to radio altimeter sensor + distance of cable from sensor to radio altimeter computer
What is the value of radio altimeter on the ground
Negative
Due to oleos being compressed
Larger plane = greater compressions
What is the required radio altimeter accuracy
+/- 2 feel below 500’
Or
+/- 1.5%
What ever is greater
