Re: 2, 3, 4 engines-- what's actually safer?

From:         msb@sq.sq.com (Mark Brader)
Organization: SoftQuad Inc., Toronto, Canada
Date:         18 Mar 93 09:03:18 PST
References:   1 2 3
Followups:    1
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> In particular, I'm interested if anyone can think of an incident in which
> a trijet survived (for some value of survived; a semi-controlled crash
> landing, such as the Sioux City crash, would qualify) where a twinjet
> would have (presumably) not done so. 

In the same article, the poster continues:

> And, of course, there are the cases of four-engined aircraft losing
> all four due to volcanic ash ingestion or the like.

As I recall, in these cases it has at least sometimes been impossible to
restart all the engines.  So this is a form of common-mode failure where
having more engines is nevertheless a big safety benefit.

In another article, it is suggested:

| Perhaps a better way of looking at it would be to ask whether there's been
| a twinjet crash which a trijet could have survived.   

Yes, there is a quite recent example.  Kegworth, England.  There was a
fire in one engine, and the crew misinterpreted the indications and shut
off fuel to the *other* engine.  QED.  (Details from memory.)
-- 
Mark Brader		    "People tend to assume that things they don't know
SoftQuad Inc., Toronto	     about are either safe or dangerous or useless,
utzoo!sq!msb, msb@sq.com     depending on their prejudices."    -- Tim Freeman

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