TCAS/ATC Transponder Control Panel is part of A320 pedestal panel
Altitude Range Switch #
The Altitude Range Switch (labeled ABOVE/N/BELOW) sets the altitude range for displaying intruders (TCAS traffic) on the Navigation Displays.
All intruders are reported as a relative altitude in hundreds of feet from aircraft’s current altitude. A + symbol indicates traffic is above and a – symbol indicates the intruder is below (i.e. +02, indicates traffic is 200 feet above aircraft’s altitude). The ABS/REL switch is deactivated.
The altitude range settings are:
- ABOVE selection displays relative altitude reporting traffic from 2700 feet below to 7000 feet above airplane altitude.
- N (Normal) selection displays altitude reporting traffic from 2700 feet below to 2700 feet above airplane altitude.
- BELOW selection displays altitude reporting traffic from 7000 feet below to 2700 feet above airplane altitude.
Transponder Code Window #
The Transponder Code Window indicates the code selected with the code selector.
DESCRIPTION –
Two ATC transponders are controlled by a single control panel. In flight, the selected transponder replies to beacon code aircraft ID (Mode A), barometric altitude (Mode C), and aircraft ID flight data (Mode S) interrogations when the transponder mode selector is in XPNDR, TA ONLY, or TA/RA. On the ground, transponder replies are inhibited for general (all call) Mode A, C, and S interrogations. However, the transponder will reply to selective Mode S interrogations on the ground that are specifically directed to the aircraft, based on each aircraft’s unique Mode S address. This function can be used by ATC for ground surveillance during taxi when the transponder is active (mode selector not in STBY). All transponder modes are inhibited when the mode selector is in STBY.
TCAS/ATC Transponder Control Panel #
Transponder Mode Selector #
STBY – TCAS and the transponders are in standby. Message TCAS STBY displays in green on upper ECAM.
XPDR – TCAS is in standby. During flight, the transponder is ON; on the ground, the transponder only responds to the selective interrogation mode of mode S.
TA – The transponder is ON. TCAS is on but only the traffic advisory function of TCAS is operational. Both resolution advisories and pitch guidance are inhibited. The message TA ONLY appears on the ND.
TA/RA – The transponder is ON and all TA and RA functions of TCAS are operational.
TFC – The TCAS/ATC system is ON and all transponder equipped airplanes within approximately 30 NM (40 NM range or less must be selected on some airplanes), and the altitude slice selected by the Altitude Range (ABOVE/N/BELOW) switch are displayed full time (Other, Proximate, TA, and RA traffic).
Code Selector #
The Code Selector uses two concentric selectors to select the transponder code.
ATC Fail Light #
The ATC FAIL Light indicates a failure of the selected transponder when illuminated.
Ident Button #
The IDENT Button causes the airplane target symbol in the data block on the ATC display to double in size.
Transponder Selector #
The Transponder Selector provides a means for selecting a transponder.
- Position 1 – Selects transponder 1 and ADR 1
- Position 2 – Selects transponder 2 and ADR 2
