MD-11 Flight Crew Operations Manual
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Instrumentation and Navigation -
Description and Operation
Inst.10.16
Altitude/Vertical Speed (CADC) Failures
For invalid altitude data, the precision altitude, scale markings, and any associated
bugs are removed and a red X is drawn through the tape. For invalid vertical speed
a red X is drawn through the vertical tape.
No Computed Data (NCD) Indications
No computed data means that a source is valid but the data is not in the valid range.
NCD Airspeed or Altitude - The precision tape digits and bugs will be removed.
The tape shading and scale marks remain.
NCD ILS Vertical or Lateral deviation - The localizer or glideslope pointer will
be removed but the scale will be displayed if the reciever is tuned.
If a difference exists cross-side (one side NCD, the other getting good data), the
NCD indication will be accompanied by a miscompare annunciation on the PFDs.
Navigation Display
Comparison Monitor Annunciation
Captain and First Officer heading and position data are cross compared in the
DEUs. FMS position is also compared with averaged IRS position. If the
difference between the parameters exceeds a predetermined value, a miscompare
message annunciation is displayed on the NDs.
The following miscompare messages can be displayed on the ND:
• HDG - IRS Heading miscompare.
• LOC - ILS Localizer miscompare.
• CHK POS - IRS/FMS position miscompare.
Inertial Reference System Failures
Failure of IRS heading information is shown by removing the displayed digital
heading value, compass scale, map data (if any), VOR bearings (ADF bearings
remain), wind vectors and selected or preselected heading or track bugs, and
displaying in red the label HDG FAIL at the top center of the ND compass arc or
rose.
FMC Map Data Failure (Map Mode)
Loss of map data allows crew selection of the associated MCDU for flight plan
data. When an MCDU is used for flight plan data, MAP STDBY is annunciated
in white on the ND in the MAP mode annunciation area (lower left corner). Loss
of FMC and MCDU map data results in the removal of all flight plan data and the
display of MAP FAIL in amber above the aircraft symbol.
November 16, 2009
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