MD-11 Flight Crew Operations Manual
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Instrumentation and Navigation -
Description and Operation
Inst.10.11
The transponders respond to Air Traffic Control Radar Beacon System (ATCRBS)
mode A, C, and S interrogations.
Aircraft with mode S transponders have the capability of air-to-air data exchange
with other aircraft with mode S transponders.
The mode S transponders can be upgraded with enhanced functionality to provide
additional information in the interrogation replies to ATC ground stations. A
primary added feature is the capability to transmit fight ID as part of the
interrogation reply. Flight ID, entered into the FMS by the flight crew, is
automatically transferred from the FMS to the mode S transponder. In addition to
the flight ID, the enhanced transponders provide aircraft status and intent
information, such as current heading, altitude, airspeed, selected altitude,
autopilot mode, etc. obtained from other aircraft systems.
Auxiliary Data Acquisition System (ADAS)
The ADAS allows additional monitoring of engine systems, aircraft systems, or
crew performance. The system consists of a Data Management Unit (DMU) and
a Quick Access Recorder (QAR). Both are installed in the avionics compartment.
Flight crew interface with ADAS is accomplished with the MCDU. EVENT
MARKER switches on the Captain’s and First Officer’s instrument panels are
used to mark an event on the QAR.
Traffic Alert and Collision Avoidance System (TCAS)
The TCAS is an airborne system that interrogates ATC transponders in nearby
airplanes to identify and display potential collision threats. Visual and aural
warnings are provided when a penetration of the TCAS protected airspace is
predicted.
Threat airplanes are displayed with data tags on the ND with different symbols
and color codes to indicate threat level of each airplane. The data tag shows
relative altitude and climb/descent in excess of 500 fpm of the intruders. TCAS
cannot detect traffic unless the traffic has an operating transponder turned on.
TCAS controls are on the transponder control panel and the EIS control panel.
A Resolution Advisory (RA) appears on the PFD and ND when a threat airplane
is about 25 seconds from the Closest Point Of Approach (CPA). There are two
types of RAs. Corrective RAs recommend changing vertical speed with a green
fly-to zone on the PFD vertical speed display. Preventive RAs recommend not
changing vertical speed with red forbidden zones on the PFD vertical speed
display. On the ND, the RAs are red squares.
Voice warnings associated with RAs for TCAS Change 7 are as follows:
November 16, 2009
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