GPWS, Windshear, TCAS

[a_320busdriver]

All three occur at the same time, which one do you give priority to? Hypothetical I know and correct answer it seems is W/S, GPWS and then TCAS.
Understand the TCAS having last priority as the other aeroplane would also be given a TCAS warning.
The other two.......I was thinking GPWS first because in the Airbus it is full back stick and TOGA with Alpha Floor protection in normal law. Also W/S recovery procedure is to follow SRS and in some cases that can demand a pitch down ie into the terrain in this case.
Can anyone shed some light on why W/S first rather than GPWS and if the Airbus design would predicate a different response.

Thx

[Swanie]

GPWS and windshear (and stall warning) override TCAS i believe
and i guess you'd give priority to GPWS over shear...

[Dick Whittingham]

This may not apply to every system, but some TCAS RAs that recommend a descent are inhibited beleow 1000ft radio altitude and RAs that recommend an increase in rate of descent are inhibited below 1800ft radio.

All RAs are inhibited below 500ft radio and all TA aural alerts below 400ft radio.

This takes out some potential conflict between TCAS and ground proximity warnings

Dick W

[Intruder]

Shouldn't be a problem at all! Response to GPWS and windshear at low altitude are virtually identical. There will be no TCAS Descend RA at low altitude.

I'll vote for missing the ground and taking my chance with a near miss if there's really another airplane out there...

[Mad (Flt) Scientist]

The logic should be to prioritise things in the order which enables you to do the next priority item more easily.

That means keeping the plane flyable at all costs. So .....

Stall warning has first call (a stalled aircraft can't do much)
Then windshear (because its eroding your aircraft's performance, and you'll need performance to take other actions)
Then GPWS (because hitting the ground removes most options)
Then TCAS, because hopefully the other guy is taking care of it too.

As mentioned, while some WS guidance may be down initially, most WS algorithms have a radalt input and won't drive you into the ground - unless the shear is beyond your aircraft's capability, in which case you'll end up hitting the ground with the shaker going off.

[londonmet]

I'll be interested in hearing Alex Whittinghams reply - whoop whoop, pull up.

Come on we've all been there.......