Originally Posted by milsabords
I'm surprised that TCAS depends on ADR. 3D coordinates and speed derived from GPS should be reliable data to feed anticollision logic.
Altitude mode (both ATC and TCAS) is dependant on ADRs.
Triple ADR fault rev.19 (compare with rev.16 above); see ATC ALTI MODE and TCAS inop:
and TCAS scheme:
