Re: Swissair MD-11 (SR 111, JFK-GVA) crash off Nova Scotia

Date:         10 Sep 98 03:04:29 
From:         JF Mezei <jfmezei.spamnot@videotron.ca>
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Pete Mellor wrote:
> Already, there are allegations of pilot error (the captain should
> not have wasted time circling to dump fuel, but should have gone
> straight into Halifax). I think the ground rules about premature
> speculation should apply here?

Pilots act based on the information which is available to them. The big
question is whether the pilots underestimated the problem initially.

I noticed that in the transcript, initial clearance was given to 29k
feet.  Perhaps a lower clearance should have been given encouraging the
plane to start to loose altitude as quickly as possible so that it can
get decent altitude by the time they get close to Halifax.

Based on information I obtained from canadian media, the plane was at
16k feet by 22:21 and 10k feet by 21:23 (which corresponds to the top of
the bay, according to this media report).  With a descent from 33k feet
starting at 22:15, it gave a descent rate of 2800 feet per minute which
the reporter said was quite normal (qualifying 3000feet/min as normal).

Based on those numbers, it would seem that the plane got to Peggy's cove
at altitude of 16k feet, and 30 miles to go, at a speed of 300 knots,
those 30 miles would have taken 6 minutes which would have allowed the
plane to drop a theoretical 18000 feet, giving a bit of a margin to
land.  (with a 2.8k feet perminute rate, those 6 minutes would have
allowed 16800 feet drop, again within limits.

Obviously my logic and data are flawed somewhere as it doesn't look that
obvious to me that a detour was really necessary.  Can anyone please
explain where I have erred in my logic ?