Program Pins

Each ATC transponder has these program pins:

· Airplane mode S address

· Source destination identifier (SDI)

· Maximum true airspeed.

There are 24 airplane address program pins on each transponder. A program switch module connects to the program pins. The program switch module supplies the open and ground connections necessary to make the 24-bit unique airplane identification.

The SDI defines the transponder as the ATC 1 or ATC 2 transponder.

The maximum true airspeed pins define the maximum true airspeed for the airplane. The transponder formats and sends the maximum true airspeed to the TCAS computer.