Safety/Emergency Procedures
Instrument Flight
RADAR ALTIMETER FAILURE
With a failed radar altimeter, you lose your height above ground reference. If you are aware of your
location and the local terrain, this danger is minimized. Remember that if you have any doubt about your
position or the topography of the surrounding area, you should notify the controlling agency and
immediately climb to a safe altitude. Once you are sure of the local surface elevation and have confirmed
that the barometric altimeter has the correct setting, you should be able to use it for all altitude references.
However, remember that where the radar altimeter supplies height above terrain, the barometric altimeter
gives height above sea level.
Figure 46 shows one of the possible indications of a failed radar altimeter. The OFF flag does not have to
be present for the indicator to give false readings. The flag indicates a power failure, that the system is
turned OFF, aircraft attitude greater than +/- 40 degrees in pitch or roll, or aircraft higher than 5,000 ft
AGL.
The procedure for dealing with a radar altimeter failure is:
1.
Use the barometric altimeter.
2.
Confirm the correct altimeter setting.
VOR FAILURE
A failed VOR system may be indicated by the loss of the aural identification or by the presence of a red
NAV flag on the HSI. If the VOR equipment fails, you will also lose ILS localizer information because both
are driven by the same circuitry. Keep in mind that altitude affects reception, so the VOR signal may be
occluded if you are operating at low altitude.
Figure 47 shows one of the possible indications of a failed VOR system. Remember that the NAV flag
does not have to be present for the VOR bearing pointer to give false readings because the flag indicates
only that the information supplied to the HSI is sensed to be invalid.
The procedure for dealing with a VOR failure is:
1.
Cycle the frequency selector.
2.
Check with ATC to see if the station is in operation or select another station.
3.
Use TACAN (if available) or request radar vectors.
TACAN BEARING FAILURE
A TACAN bearing failure (Figure 48) is indicated by the No. 2 bearing pointer searching, CDI going to
random positions, loss of audio identification, and NAV flag in view.
The procedure for dealing with a TACAN bearing failure is:
1.
Cycle the channel selector.
2.
Check with ATC to see if the station is in operation or select another station.
3.
Select the VOR navigation system (if available) or request radar vectors.
(12-00) Original
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