chapter  12
4 Low range radio altimeter
Pages 1

The low range radio altimeter (LRRA) is a self-

contained vertically directed primary radar

system operating in the 4.2 to 4.4 GHz band.

Airborne equipment comprises a transmitting/

receiving antenna, LRRA transmitter/receiver and

a flight deck indicator. Most aircraft are fitted

with two independent systems. Radar energy is

directed via a transmitting antenna to the ground;

some of this energy is reflected back from the

ground and is collected in the receiving antenna,

see Figure 12.9.