FLIGHT
INSTRUMENTS
AIRPLANE
OPERATIONS
MANUAL
2-17-25
Page
2
Code
01
REVISION 38
AOM-145/1114
RADIO ALTIMETER CONTROLS AND INDICATORS
DISPLAYS CONTROL PANEL
1 - DECISION HEIGHT SETTING KNOB
When rotated, allows decision height setting.
2 - TEST BUTTON
In flight conditions only, this button allows testing the associated
Radio Altimeter.
To perform the Radio Altimeter test the DH must be set to 200 ft
and the button must be kept pressed. The following indications are
presented on the PFD:
− A magenta TEST annunciation is presented adjacent to the
upper left side of the attitude sphere.
− An amber MIN label is displayed in the RA Minimum
annunciator. The label flashes for about 5 seconds, and then
becomes steady.
− An amber RA comparison label is displayed in the down left
side of the attitude sphere.
− The Radio Altitude field indicates 100 ± 10 ft.
Additionally, the following EICAS messages are presented
according to the following configuration:
− For airplanes equipped with one Radio Altimeter:
− If tested at LH side:
− (E)GPWS INOP
− WINDSHEAR INOP
− RAD ALT 2 FAIL
− If tested at RH side:
− (E)GPWS INOP
− WINDSHEAR INOP
− RAD ALT 1 FAIL
− For airplanes equipped with two Radio Altimeters with RA1
connected to the EGPWS:
− If tested at LH side:
− (E)GPWS INOP
− WINDSHEAR INOP
− If tested at RH side:
− No message associated
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