I've been interested by the two simultaneous threads, one a serious
technical discussion relating to buildings (waterproofing foundations) and
the other on aviation crash safety. On the waterproofing, I can only say
that I have learned from the home inspectors involved in the transactions
I've done that the #1 cause of water getting into basements is inadequate
downspoutage, or otherwise water flowing toward rather than away from the
building. But you guys would already know this. Most homeowners don't seem
to know it. 

Regarding aviation crash safety, I've thought about this a great deal. I
spent 10 years working for aviation publications, including occasionally
researching crash data. Spending a couple of afternoons reading preliminary
crash reports at NTSB HQ was educational. Every transportation incident or
accident (it is an accident if an impact occurs) involving commercial
transportation (trains, ships, airlines) or any kind of aircraft is
supposed to have such a report, similar to the kind that are filed with
local police after car accidents. Usually these are just one-page
summaries. What I found, initially, was that commercial pilots have a much
better safety record than private pilots, and that the majority of reports
are 'airborne fenderbenders' or even non-accidents, since the airlines as a
matter of course report every incident such as a sudden unexplained loss of
altitude, even if no detectable damage or injury results (they do this in
part in case some passenger later on tries to claim injury). Major
accidents, ones which the NTSB decides should be lessons for the industry,
are eventually reported in great detail in 'Blue Books'. All of this
information is considered public knowledge and is available to anyone who
wants it. 

To my knowledge, the last time any airliner ditched in water with survivors
was 1935, when one of the Pan Am Clippers landed in the North Atlantic in a
storm and the passengers and crew were rescued by the US Coast Guard Cutter
Bibb, still regarded as one of the great sea rescues. Because the Clipper
was a flying boat, it was able to remain afloat after landing, but in the
storm conditions (which were far in excess of what it was designed to land
in), it was sinking and the rescue operation was a race against time. The
Bibb happened to be nearby because at that time (and for some decades
thereafter), the USCG maintained weather patrols in the North Atlantic, and
she just happened to be close to where the plane ditched. Today there would
probably be no one around if a plane landed in mid-ocean. It was rather
improbable then. 

To this day, all airliners that fly over water are required to be prepared
for controlled ditching in water, even though, to my knowledge, no modern
airliner has even done so successfully--I do recall one instance of a JAL
747 landing in Boston Harbor right after takeoff (and that was a suicide
attempt on the part of the pilot--he took off with thrust reversers full
on--killed 100 passengers and HE survived). There is something poignant
about the safety instructions including how to wear your life vest and that
the emergency escape slides (also seldom used) are designed to function as
life rafts. I believe the point of view is that since it is theoretically
possible, they have to be prepared for it (even at a cost of millions of
dollars for equiment that is never used)--and what if some airliner did
ditch and everyone drowned because there were no life vests. It helps keep
the familes assured that there was nothing else that could have been done. 

Most of these regulations date from when aircraft were smaller and slower,
and the possibility of surviving a crash greater. If this sounds
reminiscent of the Admiralty allowing the Titanic to carry fewer lifeboats
than were needed for her entire population (the rules had not adapted as
fast as the ships which grew very quickly in size and speed in a few
years), it is actually the reverse of that situation. 

There has probably been discussion of air bags in aircraft, with probably
the objections raised that have already been made here about the
practicality of having them work properly in an airliner with all the
variables of passenger size and distance from passenger to airbag. Also
there is the matter of cost. This always sounds callous in this context,
but it would be hugely expensive to put airbags in an aircraft fleet, and
quite possibly not one life would be saved---indeed the airbags themselves
might injure or kill someone. 

The NTSB, in the aforementioned Blue Books, always includes a statement as
to whether the crash was 'survivable'. This always seems a bit odd when
discussing a crash that no one survived, but it is a defined technical
term. What they mean is that had the occupants been adequately protected by
the systems available to them, the initial crash would not have killed
them. This then brings up whether the systems (seat belts etc) were in use
and whether the occupants were killed by fire or smoke before they could
escape from the aircraft. Certainly the issues of 'secondary impart'
(impact of occupants with objects inside the aircraft) is also considered
in this evaluation. It's the secondary impact that does the damage in the
car, too, and what seat belts, air bags and eleminating hazards in the
interior design are all intended to prevent. 

Because aircraft have to fly, they have to be light in weight (relatively
speaking). Their strength/weight ratio is probably better than that of any
other vehicle. As for fire resistance, jet fuel is just a very pure grade
of kerosene (as are diesel fuel, heating oil and rocket fuel), which is
less flammable than gasoline (because less volatile) but given enough heat
at impact, this is scarcely significant--as we have all seen, far more than
we would like to remember. 

Don

PS. For anyone who was looking for me at IPTW, I am sorry to have missed it
this year, but I was fighting with a flu-like something or other, it was
beastly hot, and further away than Floyd Bennet Field would have been. I
stayed home & indoors for a few days, until whatever it was got better (or
rather, I got better). 

DW

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