Re: 26 "Things That Do Not Make Sense"

In article
<8d5b15c3-8549-4ba5-b8a3-d809899b4b31@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
cryptoguy <treifamily@xxxxxxxxx> wrote:

Both bays are salt water, but I wouldn't expect either to have the sort
of waves one routinely expects in oceans.

I thought the question you asked was 'Do the rafts/life jackets/water
landing instruction ritual on planes do anything by provide a false
sense of security?'.

The question I actually asked was:

"Has any such plane--big commercial passenger jet--after made a soft
landing on the ocean? Any ocean?"

The answer seems to be "no," unless you count a bay as ocean.

Clearly, unless a plane lands in water shallow enough to wade, they
do, regardless of whether the water is salt, fresh, a river, or a bay.
But now you've moved the goalposts to requiring their demonstrated
utility in an open ocean landing.

On the other hand, the cases of successful water landings that we have
found are so few, given the number of flights that occurred over the
past fifty years or so, that if that's it the feeling of security indeed
is false, the substantial precautions being of use under circumstances
that virtually never occur.

A quick google didn't find a figure for total number of commercial
airline flights. Total number of aircraft departures in the U.S. (from
the Statistical Abstract) is about ten million a year, but I assume a
large fraction of those are small planes. Total revenue passengers is
around 700 million a year, so if we assume an average commercial plane
carries 200 passengers that gives about 3.5 million flights a year.

Taking that as a very rough guesstimate, and allowing for increase over
time, that suggests that over the period we are looking at there have
probably been well over a hundred million flights worldwide--of which
fewer than ten ended with a water landing which a significant fraction
of the occupants survived. So call it less than one chance in ten
million.

I wonder what the total weight of life rafts etc. is? That would give us
at least a rough idea of how much the precautions in question cost, in
terms of reduced passenger and cargo carrying ability.

Also, in the handful of cases that did happen, I wonder how useful the
apparatus was. In the case of Japan Airlines 2, they did inflate the
life rafts--but since the plane was floating in SF bay 350 feet from a
yacht harbor, I suspect life jackets would have sufficed to get the
passengers to safety.

For NA 193, Wikipedia says that barge traffic in the area assisted in
the evacuation, which at least suggests that the life rafts weren't
needed.

--
http://www.daviddfriedman.com/ http://daviddfriedman.blogspot.com/
Author of
_Future Imperfect: Technology and Freedom in an Uncertain World_,
Cambridge University Press.
.

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