Why the concern over selecting TA Only?
If you really have decompressed, and perhaps have suffered some kind of structural damage, you wouldn't want an RA telling you to climb or carry out some kind of radical high G manoeuvre. Wouldn't you leave the dodging to the most able aircraft?
Firstly: it is a Eurocontrol specification. Secondly; with my limited knowledge of how TCAS really communicates in an intruder scenario: you are cruising relaxed in level flight. An intruder is hurtling towards you at high ROD. Who do you think will get the RA to move first? I suspect the high ROD will get an RA to 'reduce V/S'. I've asked the question to technical pilots and had no reply, hence my quest here. But, if it is true, my assumption, do you really want an RA telling you to adjust your Emergency descent?
Don't be jump down my throat too fast, I'm seeking the correct answer. In the decompressurised environment, with all the noise and reduced visibility, lousy crew communications etc. do you really want a moment of "what shall we do/confusion" telling you to reduce or stop your descent? Personally I doubt it. It is Oh so simple in the sim every 3 years; nice and clean and relaxed; but in anger I suspect very very different.
Regarding ATC clearance. As soon as you deviate 300' from assigned crz level radar screens will give an alert to ATC who will then start shouting at you to maintain level. You start shouting back with Maydays. Is this the best team work? What's the rush? There's enough O2. and you and pax should be on O2 before the E.D is commenced. I'd always thought good teamwork in an emergency required good communications. Does it really take more than a few seconds to include ATC in your scenario and then have a smooth relaxed executed manoeuvre with everybody knowing what's going on, with perhaps an ATC HDG change, rather than appear as a surprising bowling ball hurtling at skittles vertically below you and asking ATC to sort it out. There's no panic; and you could make a bad situation worse.
It's a discussion point guys. I don't believe there's black & white. There will be many diverse opinions. I wonder if the procedure in the jet age has been reviewed from operational historical data, and if it could be improved. Or has it been written in an office, tried in the sim and cast in stone forever?
Perhaps someone from ATC could contribute their opinions. They will be a major player in such a scenario. It will be interesting to know how they will react .
Last edited by RAT 5; 1st Jun 2013 at 10:20.