Re: ETOPS Question

Date:         17 Sep 97 02:49:17 
From:         Steve Lacker <look@the.sig>
Organization: Applied Research Laboratories - The University of Texas at Austin
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Peter wrote:
> > > I have a basic (hopefully not dumb) ETOPS question:
> I have another: Following an engine failure, is there any actual
> requirement to land at that alternate airfield [180 or 60 or whatever
> minutes away] or can you continue all the way to the destination on one
> engine?

I think it is a requirement. Logically it SHOULD be, especially for a
twin. Think about it: one engine is inop so your safety margin is gone.
You fly or glide depending on that last engine. Also, while its *most
likely* just a problem with one engine, there is always the chance its
not. In most ways, the probability that any given engine on  an airliner
will fail is statistically independent of whether or not other engines
have failed... but for some causes, the conditional probability that an
engine will fail given that another has already failed is *higher* than
the probability it will fail given that no other has failed. What if it
wasn't a mechanical failure but contaminated fuel? What if it was a
maintenance error done to both engines (or all 3- remember the L-1011
with missing O-rings on all *three* engines?).

Stephen Lacker
Applied Research Laboratories, The University of Texas at Austin
PO Box 8029, Austin TX 78713-8029