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[Chris Scott]

VS (fin) and VS (vertical-speed)

'Morning JD-EE,
Normally an admirer of your arguments, I must admit your post #3346 leaves me nonplussed.

Quote:
"Chris Scott, I believe it's pretty clear the VS was with the plane until impact or very nearly to impact (15 seconds or less). The is no reason for the plane in a level attitude to lose contact with the satellite as long as it had power.
If the plane was in the last 15 seconds of its flight with the VS still attached, please describe how it came off before impact."

I happen to believe the BEA's finding that the "VS" (vertical stabiliser) was still attached at impact, but have never discussed the subject. Looking at my recent posts, what I have been discussing is "Cabin VS" (notional vertical-speed of cabin in terms of its air-pressure variations), in the context of the final ACARS message. Could the ambiguity of the term "VS" have caused your misunderstanding? If "vertical stabiliser" is too much of a mouthful, perhaps we could use the good old British term: "fin".

I've never discussed the conditions that might result in the ACARS antenna losing sight of the satellite. What I have discussed are possible reasons for failure of electrical power to the aircraft's ACARS system.
Are you mixing me up with someone else?

Quote:
"If the engines flamed out at altitude I suppose it is possible for the plane to sink in a power lost condition to the surface at that time. But, how does the CPC malfunction to provide the messages received BEFORE the engines flamed out?"

Agreed. I don't think there is any evidence that the CPC malfunctioned. I discussed the unlikely scenario of a double pack-failure (possibly caused by double engine-failure) in my post #3316, concluding:
"However, I would have expected double pack failure and double engine-failure both to be ahead of cabin VS in the ACARS message hierarchy..."

In other words, I think the shutdown of both air-conditioning packs would produce its own warning before the CPC noted the (resulting) cabin VS outside limits (cabin-altitude climbing). Like others, I think that the cabin VS warning was more likely created by a serviceable CPC noting the cabin-altitude suddenly descending at a VS outside limits; due to the aircraft descending rapidly through the cabin altitude of about 6000ft-7000ft, resulting in the opening of the inward-relief valve(s).

When proposing explanations for the final termination of ACARS messages, the latter scenario makes a complete loss of main AC-generation unnecessary prior to impact. At the suggested impact-VS of about 18000ft/min, there may have been fewer than 30 seconds of flight remaining at the time that last message was generated.