MD-11 Flight Crew Operations Manual
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Instrumentation and Navigation -
Description and Operation
Inst.10.15
• RAD - for radio altitude.
• HDG - for IRS heading.
• LOC - for localizer.
• IAS - for CADC airspeed.
• G/S - for glideslope.
Inertial Reference System (IRS) Failures
If IRS pitch or roll fails, the attitude sphere pitch scale is removed, the sphere turns
cyan, and a red ATT FAIL appears in the top center of the sphere. If IRS heading
data fails, the heading value and scale are removed (lower PFD) and a red HDG
FAIL appears.
Flight Director Failure
If the flight director fails, FD mode annunciations and command bars are removed
a a red FD FAIL is shown below the roll control window (upper right PFD).
Loss of ILS Data
Loss of ILS data will be annunciated on the PFD as follows:
• NO LOC (cyan) - on the lateral deviation scale when the localizer is
initially tuned. NO LOC is removed after a deviation is continuously valid
for 10 seconds.
• NO LOC (amber) - on the lateral deviation scale when the localizer is
initially received.
• NO G/S (cyan) - on the vertical deviation scale when the glideslope is
initially tuned. NO G/S is removed after a deviation is continuously valid
for 10 seconds.
• NO G/S (amber) - on the vertical deviation scale when the glideslope is
lost after is initially received.
• X (red) - on either scale indicates failure of the associated receiver.
Radio Altimeter Failure
If the radio altimeter system fails, the RA shading on the attitude sphere is
removed and the radio altitude sphere is removed and the radio altitude is replaced
with an amber X within the white radio altitude box.
Airspeed/Mach (CADC) Failures
For invalid airspeed data, the precision airspeed, scale, and any bugs are removed
and a red X is drawn through the tape. Invalid Mach data is indicated by a
replacement of the precision Mach value with amber dashes and removal of all
Mach bugs.
November 16, 2009
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