Re: Crash of SR111

Date:         09 Sep 98 04:12:09 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>A thumbnail calculation says the MD11 was unlikely to be more than 100,000
>pounds over MLW.

AvLeak's Source Book says typical MLW is 440,000 lbs and JP says the
accident aircraft's MGTOW was 618,000 lbs.  Boeing's web site says fuel
capacity for a standard MD-11 is 38,615 gallons.  One gallon of fuel is
very roughly 6.7 lbs (depends on temperature and other facts, but its a
reasonable back-of-the-envelope figure), giving a maximum fuel weight of
259,000 lbs.

However, the pilots radioed "fuel on board is two-three-zero tons" according
to the transcript at http://www.abcnews.com/wire/World/AP99987130.html,
which seems far too high whether you take that as tons = 2,000 lbs or
tonnes = 1,000 kg.  The cockpits of recent Boeings which I've been in
(all on United) have fuel measurements in hundreds of pounds -- maybe
with the decimal to make it thousands.  Could they have meant tons =
100 lbs, i.e., 23,000 lbs of fuel?  Assuming most of the fuel is used
during climb to initial cruise for a flight of this length (about half
the aircraft's range), this seems plausible, which would suggest the
aircraft was at most about 20,000 lbs overweight -- even less problem
for an overweight landing than with your 100,000 lbs thumbnail figure.
(Which is not to lend credence to the idiot relatives claiming the
pilots were stupid for "wasting time" by dumping fuel.)

One other bit of data, also from JP -- the seating config was 18/42/197
for a total of 257, so with 215 passengers the aircraft was about 84%
full.  No idea on cargo.

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