ATC TRANSPONDER – GENERAL
The Air Traffic Controller (ATC) Transponder (XPDR ) module has the
encoding and decoding capability to operate in Mode A, Mode C and Mode
S
Mode S allows digital addressing of individual aircraft and it is fundamental
for the operation of the Traffic Collision Avoidance System (TCAS).
TCAS is optional installation on the AW139 helicopter.
ATC XPDR – MAIN COMPONENTS
The ATC XPDR main components are:
• the XPDR module (inside MRC 2)
• the XPDR antenna
ATC XPDR – PRINCIPLE OF OPERATIONS
The ATC XPDR modes of operation are:
• STANDBY: ready but not replying
• ALT OFF: Transponder modes A and S, no altitude reporting
• ALT ON: Transponder modes A, C and S, altitude reporting enabled
• TA: TCAS is enabled, if installed