ATC Transponder - Control and Coordination Data

When you select an ATC transponder, it sends this ATC control panel data to the TCAS computer:

· The TCAS mode selection (TA only or TA/RA)

· Control of the altitude limits for the TCAS display that shows on the navigation display (ND).

The TCAS computer uses this data from the ATC transponder to calculate the climb or descent to prevent a collision:

· 24-bit airplane address

· Barometric altitude

· Maximum true airspeed.

The TCAS computer sends this to the ATC transponder:

· General TCAS operational status

· Mode S coordination data.