Re: ETOPS

From:         rdd@netcom.com (Robert Dorsett)
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
Date:         10 Oct 96 11:29:29 
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In article <airliners.1996.1975@ohare.Chicago.COM> faurecm@halcyon.com (C. Marin Faure) writes:
>
>There aren't any risks, any more than there are on any flight in a modern
>commercial jetliner.

There are more risks, hence the operating and regulatory requirement imposing
extraordinary crew, airframe, maintenance, and dispatch procedures for ETOPS
operations.

I'd still like to see whether these fabled "safety analyses" "proving" that
twin operations are as good as others take into account the recent history
involving volcanic dust ingestion.  In each case, *multiple* engines were
shut down, and *multiple* engines and systems suffered severe damage.  If
it's a question of eeking out every last bit of thrust, I'd much rather
be in a 747 (or even an A340) for transpacific travel.


>And since twin-engine ETOPS planes use the same types of systems used in
>three and four-engine airplanes, the chances of an inflight problem are
>the same for all of them.

The problem is, you lose one engine, you've lost half your redundancy.
You lose two in a 747, you've lost half of your redundancy.  You lose
two in a 777, you're going swimming.


>Actually, there are less risks in an ETOPS airplane because not only does
>the plane have additional backup capabilities in the critical systems, but

But why do they need additional backups if the basic components are so
reliable?  :-) We can go a looooong way with this kind of logic.





--
Robert Dorsett                         Moderator, sci.aeronautics.simulation
rdd@netcom.com                         aero-simulation@wilbur.pr.erau.edu
                                       ftp://wilbur.pr.erau.edu/pub/av