Airbus : Why no TCAS Cb reset on air ?

[alexious85]

Hello .
Any idea why the Airbus QRH reset procedure for a faulty TCAS is for ground only ? What on earth can happen if you do it on air ?

[Fursty Ferret]

I can think of two possibilities - one, that a TCAS computer waking up in a grumpy mood might lead another aircraft to unnecessarily carry out an RA, or two, the computer just won't start while it's in flight due to self tests etc so there's no point in trying.

Edit: if you have auto-TCAS installed on your A320s I imagine that the situation is even more complicated.

[CrazyStuntPilot]

On the ground you can have a spurious NAV TCAS FAULT during alignment. The ground reset allows to cancel this spurious fault.

In flight, the TCAS auto-resets automatically therefore a C/B reset is not needed. Airbus considers NAV TCAS FAULT in flight as not recoverable.