Re: ATR-72's and Airbuses

From:         wangermn@barder.Princeton.EDU (Pablo Wangermann)
Organization: Laboratory for Control and Automation Princeton University
Date:         28 Oct 96 03:04:42 
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In article <airliners.1996.2176@ohare.Chicago.COM>,
Robert Dorsett <> wrote:
>Various responses, since I've actually read the book.  I hope that doesn't
>disqualify me from taking place in this discussion.
>In article <airliners.1996.2149@ohare.Chicago.COM> (MikeM727) writes:
[Lots of discussion snipped, but I had to comment on this]
>IMHO, the troubling thing about the book has nothing to do with the ATR-72.
>It has to do *with* ATR, the consortium.  Frederick makes some disturbing
>allegations as to ATR's reluctance to fix the problem, denying that a problem
>existed (even after a crash in Italy), exerting pressure against the
>Americans (influencing the French to threaten certificate action against
>the 737 for the two unexplained crashes), and, most especially, threatening
>LEGAL action against any critics.

Woah there!  Let's be careful.  Before I start, I haven't read the book,
and I'm not defending ATR, but they do have a right to feel that the FAA
was not quite fair in their handling of the issue.

The ATR42/72 did pass all the FAA icing test requirements during
certification.  All planes out there have to pass these tests.  However,
the icing conditions that caused the crash (supercooled droplets) is pretty
rare and is not part of the certification requirement.  Now, it is clear
given the accident and a couple of other incidents that the ATRs need
better de-icing to cope with these conditions.  However, I've seen no reports
on whether any other aircraft have had control problems that were due to
similar icing conditions.  I believe the FAA or NTSB mused about testing
other types of aircraft under similar conditions, but with the icing tanker
now decomissioned I'd say the chances of that happening in the near future
are minimal.  I wouldn't trust _any_ prop in those icing conditions.  (I
think this was part of ATR's argument - the pilots knowingly flew the plane
in severe icing conditions - a definite no no.)

As for the 737s, I bet if a plane that a) wasn't a Boeing b) didn't have
over 2000 units in service had 2 unexplained crashes the FAA would have
grounded it by now.  It took another near accident (the Eastwind incident)
to kick the authorities into gear and actually talk about making changes to
the rudder system.

Conclusion: yup, ATR should have just got on with improving the icing
system, but some of their beefs about the US authorities are partially
justified.  Oh, and you shouldn't feel safe in any turboprop flying through
supercooled droplets.

John Wangermann