Captain Stable
no time to think how useful you think the RA is.
<nods> I see, in the original TCAS guidance / authorisation to disregard an RA if the intruder is visually spotted, a concept of "you don't have to do it if you don't think its necessary". I don't advocate that at all.
I also agree that we should not be suggesting that people spend time thinking about. I'm just saying that it ought to be allowable to take account of clear obvious dangers.
alf5071h
A RA will not fly the aircraft into the ground.
Yes it can. You just need sharp enough terrain, or a high obstacle like a tall mast on a ridge, coupled with a non functional terrain mode on EGPWS. Plenty of places I operate to have topography that TCAS radalt based inhibitions will not protect against, so its down to EGPWS.
Mandate that EGPWS must be serviceable (rather than MELable), and that serviceability is contingent on having an up to date database. E.G. right now I fly to a destination where, inspite of the fact that a new runway has been in use for several months (and obviously planned for for years previously),
we are turning our EGPWS terrain mode off because the runway isn't in the database. (so that aspect at least is NOT a highly unrealistic scenario)
If the regulators mandate these points, then I'd be a lot happier.
it provides the safest option for the situation, including other aircraft and their flight paths
Apart from non transponding / non altitude reporting traffic. There has to be the possibility of TCAS directing you into the flight path of such an aircraft. If you operate to regional airports this is a real threat.
Mandate altitude encoding transponders, and mandate they be used, and I'd be a lot happier.
With GPWS there were many accidents which could have been avoided if crews had followed the warning;
Agreed. But there is a big difference between GPWS and ACAS. The ground won't get out of your way under any circumstances. If it comes right down to it, a possible air hit is a worthwhile price to pay to avoid a certain ground hit - hence why EGPWS and Windshear have priority.
With RA non compliance by one aircraft only (because it has a threat in its RA sense, the other aircraft won't) the chances of a successful resolution should still tend towards 100%.
CPB