Petitfromage,
V. good points, especially about the change from "Climb" to "Descend, descend now".
This
link, specifically p. 35, rh coloumn, second-last paragrpah, indicates that TCAS manouvres are designed around a 0,33 delta-G manoeuvre. Therefore, nothing suggests that a 2,5/-1,0 (or shouldn't it rather be +2,0/-0,0, since flaps may be extended?) G manoeuvre would ever be commanded.
The above link also (in several places) points to TCAS being designed for vertical speeds of up to 10.000 fpm - and therefore that any manoeuvre - even during an emergency descent - will be subject to the same manouvre laws as your "everyday" TCAS.
The word "emergency descent" seems to jumble a few priorities (see above) - how long does your crew oxygen last? Cabin crew? OK, so nobody requred for the safe operation of the aircraft will be incapacitated by interrupting your emergency descent. Even the passengers will not be incapacitated - the emergency descent would be resumed long before their oxygen systems run out (worst case I've heard of is 12 min.)
Trying a bit of math here: -1 min. from the masks drop to start the descent, -3 min. to resolve an RA - that's 8 minutes left to descend from FL410 to FL130 - this requires an average rate of 3500 fpm. Or 3875 fpm to descend all the way to FL 100. Does this sound undoable?
None of the above has altered my argument - a collision
will kill everybody - here and now. The lack of oxygen
might kill some passengers in a future 10 minutes away. Now - balancing those two scenarios against eachother, I have no doubt in my mind what I'll do. I would do the same if I knew that I
would - with absolute certainity - kill 10% of the passengers doing so. Even if I knew it would ultimately kill the flightdeck & cabin crew - but save some of the passengers for now (not talking about how they'd get the thing landed - in that instant, there is a long way to the tollbooth across that bridge) - I would do it.
Statistics - don't you just love them
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