HC,
you are quite correct that EGPWS would not have given any warning other than "Altitude" based on the descent through the RA setting and "One Hundred" on passing 100 ft rad-alt in the cases I mentioned, as a pure EGPWS function. The AVAD would have (and did) anounce "100 ft" (plus the little fanfare which I can't type!). The "minimums" call is not an EGPWS function but uses the same voice synthesiser. Whether this call would have been triggered would have depended on the settings made at the time (hypothetical). It is, of course a BAR Alt triggered warning, not rad-alt.
My point was that AVAD hadn't helped in those cases, not that EGPWS would have.
That is precisely the point you make that Nick could attempt to defend, as I agree that many of the thresholds and IAS/ALT slopes are not going to catch the likely CFIT scenarios that we have seen occur offshore. The ones that are real, and have happened, not supposed scenarios.
Regarding the grating voice; I'm in favour of it. That's the whole point; it should grab you and demand a response. Clear SOPs should address this, so that rather than inhibiting the voice, you give a positive response to it: "visual landing" or "expletive deleted, going around."
I suspect the reason the algorythms are as they are, is that the motivation for Sikorsky developing EGPWS for their aircraft was driven by the S-76 accident statistics, which were about 75% CFIT. However, a very large proportion of the S-76 fleet are EMS and Corporate, so that statistic is not entirely surprising. More importantly, their operating regime is not the same as offshore. (As I say, that's my theory, but obviously Nick can, and no doubt will, correct it as required)
Last edited by 212man; 6th Nov 2006 at 13:00.