Operation Manual Part 2

Aerosoft – Digital Aviation
CRJ-70 & CRJ-900
AOM PART 2
Systems Description
VOL
5
5-1-64
26-Jul-2017
RADIO ALTIMETER SYSTEM
Two radio altimeter systems provide an accurate measurement of the aircrafts altitude over ground within -20
to 2,500ft AGL. The following systems receive data from the radio altimeter:
• PFDs
• Spoiler and stabilizer control units (SSCU)
• Enhanced ground proximity system (EGPWS)
• Traffic alert and collision avoidance system (TCAS)
The PFDs specifically receive the following information from the radio altimeter system:
• Radio altitude readout
Shown as a digital readout as soon as the aircraft descends through 2,500ft.
A moving tape / analogue scale is added as soon as the aircraft descends through 1,225ft.
• Decision height readout
Decision height is selected on the air data reference panel
• Decision height alerts and radio altimeter fail flags
• In case a failure of the radio altimeter is detected, a fail flag is indicated.
A test button on the air data reference panel allows initiating a self-test of the radio altimeter system.