Re: ETOPS Question

Date:         07 Oct 97 14:10:17 
From: (Malcolm Weir)
Organization: Little to None
References:   1 2 3 4 5 6 7 8
Next article
View raw article
  or MIME structure

On 06 Oct 97 02:14:26 , kls@ohare.Chicago.COM (Karl Swartz) caused to appear
as if it was written:

>>As I recall, G-BDXH (BA's 747 glider) flew for nearly 30 minutes before they
>>got the engines back, and I think they started at 37,000ft.  The engines
>>were restarted at about 10,000ft, as I recall.
>They were only a glider for 12 minutes -- they lost #4 at 9:42 local
>time and the other three a minute later, all at FL370.  They relit #4
>at about FL135 at 9:55, then brought back the others over the next
>several minutes.

You're right (although I believe the glide lasted 13 minutes, which is
otherwise lost in the rounding of the seconds).  I was (incorrectly)
thinking of the duration of the emergency... which was 28 minutes (they
touched down at Jakarta at 10:10 local).

[ Snip ]

>>Of course, this aircraft had an APU running during the Jakarta Volcanic
>>ash emergency ...
>Are you sure?  Nothing I've read about the accident mentions the
>pilots starting the APU, and it would not have been running at

Again, you are correct (in essence), although the APU was started (by Barry
Townley-Freeman, the FE) once they were on the ground  8-)

I was thinking that the aircraft was not relying wholly on batteries, and
that recollection was correct: the generator in #3 remained on-line and
providing power even though the engine was only windmilling.

Getting back to the topic of sink rates: immediately after the engines
failed, the aircraft had a 500fpm sink, which increased as it slowed,
stabilizing at about 2000fpm when the oxygen problem appeared, which lead to
an emergency dive at around 6000fpm.

Given that the aircraft was at FL370 when the emergency occurred, one can
estimate that the total glide time would have been of the order of something
over 20 minutes,  (which was the original question).