MD-11 Flight Crew Operations Manual
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Instrumentation and Navigation -
Description and Operation
Inst.10.5
The NLG G/S antennas are automatically selected when the nose gear is down.
Both G/S antennas must be in the NLG configuration for dual land operation.
Single land configuration is allowed for a single NLG G/S antenna configuration.
Multi-Mode Receiver (MMR)
The MMR system provide ILS and Global Navigation Satellite System (GNSS)
functions and replace the existing stand-alone ILS and GNSS receivers installed.
The MMR ILS function detects the differences in the 90 Hz and 150 Hz modulated
signals from the ground station to provide glide slope and localizer deviation
signals to the Autoflight system and to the EIS for display on the PFD and ND.
The GNSS function of the MMR receives and processes the satellite RF signals
from the NAVSTAR GPS satellite constellation to provide data to different
aircraft systems.
The system components includes two MMR (ILS/GPS) receivers (located in the
main avionics rack), two GPS active antennas and utilizes the existing localizer
and glide slope antennas.
The system interfaces with the following: FCC, EIS, FMS, IRS, EGPWS, AMU,
Data Management Unit (DMU), DFDAU, and Centralized Fault Display System
(CFDS).
Primary frequency tuning for the MMR is supplied by the on-side MCDU. If a
failure is detected, tuning will be received from the off-side FMC.
Global Navigation Satellite System (GNSS)
The GNS system consists of two GPS receiver units, either a Global Navigation
Satellite Sensor Unit (GNSSU) or a Multi-Mode Receiver (MMR). GNS 1 and
GNS 2 are independent, each simultaneously tract signals from up to 12 GPS
satellites and process these signals to provide a three-dimensional position,
velocity and precise time estimate to the FMS, EIS and EGPWS. GNS system
operation is automatic and requires no pilot interaction.
The Flight Management Computer (FMC) IRS/GNS POS page 2/3 displays GNS
position data. GNS 1 and GNS 2 latitude/longitude position and bearing/distance
relative to FMC position are displayed in lines 4 and 5 respectively. Each GNS
label line indicates current status (i.e. ACQUIRE, NAV) and to the right the
current number of tracked satellite vehicles (SV).
GNS failure status is provided on the FMC SENSOR STATUS page. If a GNS
fails, the SENSOR STATUS page will display FAIL for the appropriate unit (e.g.
GNS 1 FAIL), the CDU MSG will be displayed on the ND and the SENSOR FAIL
message will be displayed on the MCDU scratchpad.
October 02, 2006
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