Of couse the converse is true, if YOUR family/firends were the ones hit,
would't you like to be able to prove the other poerson was speediing and did
not have the brakes on etc etc. ???
BTW, Corvette already has a black box on it.
For many years I have wondered why there is such a difference between
the way automobile accidents are treated and the way aircraft accidents
are treated: even the crashes of small planes where the only person
killed was the pilot seem to be investigated a lot more thoroughly than
multi-vehicle accidents are.
OTOH, why is one supposed (in many places in the US, at least) to call
the police for motor-vehicle accidents involving no injuries and trivial
property damage? I have lived in places where the police had to be
*notified* (not called to the scene) within a certain time period
(24hrs? 48hrs?) only if damage in excess of a certain sizeable amount
occurred. Yet our local paper reported recently that someone was in
trouble for leaving the scene of an accident when all she did was hit a
On 08/04/04 12:10 pm TOM KAN PA put fingers to keyboard and launched the
following message into cyberspace:
Probably the biggest reason is that there are so many more car accidents
than airplane accidents. If car crashes were investigated as thoroughly
as airplane crashes, you would need a veritable army of investigators.
But perhaps if motor vehicle accidents were investigated more thoroughly
it would lead to better driver training, better design of vehicles,
better road design, construction and maintenance, better signage, better
. . . -- and therefore fewer accidents.
On 08/05/04 07:50 pm Matt Whiting put fingers to keyboard and launched
the following message into cyberspace:
I've no doubt it would have some benefit, but you don't need better
accident investigation to know that driver training is a problem as are
many other things that are well known. Unfortunately, the issue with
most of these is politics, not lack of crash investigations.
Design flaws and inadequate maintainence schedules for airplanes are
realistically more deadly in aircraft hence why aircraft accidents are
investigated more. Aircraft also tend to be much older (on average)
than cars. Aircraft are MUCH more vulnerable to structural failure
than cars (as a cause of accidents). Engines and avionics need to be
much more reliable and durable than for a car.
It's critical that pilot error be identified (or ruled out) for
aircraft accidents. For car accidents, it's pretty much a given that
it was driver error 99.999% of the time (as opposed to equipment
failure - ie tire blowing out). For multi-vehicle accidents, the
question is which driver was at fault (or how to divide up the fault).
Police are (basically) armed stenographers. Most of what they do is
paper-work, and much of that paperwork finds it's way to insurance
companies for one reason or another.
Structural failures are VERY rarely the cause of an aircraft accident.
I'd like to see your source of information that says aircraft are MUCH
more vulnerable to such failures as compared to cars.
Yes, engines need to be more robust in airplanes for two reasons:
1. They are called upon to work much harder than in cars. Most piston
engine airplances cruise at 65-75% of their maximum rated power. Most
cars seldom see these levels of power and cruise at less than 25% output
2. Engine failure in an airplane has much greater consequences typically.
The downside of this is that new technology is very slow to make it into
airplanes, other than in avionics. But most avionics failures are of
much less consequence than a powerplant failure.
Actually, I can think of 5 structural failure incidents within the last
10-15 years without even scratching my head, and only considering
1) A Lockheed L-1011 rear pressure dome fractured, forcing a return to
the takeoff field (in Japan, IIRC) and subsequent scrapping of the
aircraft (could have been repaired, but was more costly than the
airplane warranted). It was a fatigue failure.
2) 747 pressurization failure (also a rear P-dome I think) that caused a
loss of the aircraft and many passengers, also in Japan. Fatigue failure/
3) The most famous one- the Aloha Airlines Boeing 737 "convertible" that
lost the upper half of the fuselage above something like 10 rows of
seats. At least 2 deaths, I believe. Fatigue/corrosion failure of the
4) American Airlines Airbus A-310 (or was it an A-300?) over New York.
Rudder broke right off. The root cause is now looking like pilot error
(excessive rudder input) but it was certainly exacerbated by flaws in
both the design and a particular repair performed on the aircraft's
composite vertical stablizer.
5) Alaska Airlines MD-80 off Port Hueneme, CA. Elevator control
jackscrew shed all its threads resulting in the elevator being
un-controllable. All lives lost. The root cause turned out to be that
the wrong grease was used on the jackscrew, but the immediate cause was
a mechanical failure of the jackscrew.
Going back further, there was the Lockheed Electra engine mount problem
that cost a couple of airframes in the 60s, and of course the very first
jetliner (DeHavilland Comet) had its career cut short when several
airplanes were lost, and it turned out that the fueslage was splitting
like a sausage because of fatigue failure at the window frame corners.
Then we have military aircraft: the Lockheed C-141 Starlifter main wing
spar replacement program (due to cracking), the early retirement of the
F-105 Thunderchief due to wing cracking, two fire-tankers lost
year-before-last (including one C-130 caught on videotape) because the
main wing spar failed and the wings came off during flight.
Even private aviation has had issues- the Beech 1900D (a derivative of
the King Air turboprop) had an engine mount failure mode that cost at
least 1 airframe and several lives.
And beyond the actual accidents, ALL airframes have a limited structural
life beyond which they must either cease flying or be very thorougly
inspected and reinforced. In some cases the predicted life has been
exceeded and extended (The Douglas DC-8 is still hauling cargo with many
good years left, as is the Boeing 727) and in other cases like the
Starlifter, the initial lifetime estimate was grossly under-estimated.
in contrast, when was the last time you heard of a car wreck because a
part of the chassis failed due to fatigue? it DOES happen (google for
BMW Z-3 differential mount failures...) but not to near the extent it
does with aircraft. Most cars are STRUCTURALLY over-built by huge
margins. Aircraft are not, or else they would be grossly inefficient and
I disagree. How many automobile engines use advanced ceramic coatings
(besides the 5.7 Hemi, of course :-) ), or "single crystal" metal
components? It is quite common in aircraft engines, and has been for at
least 10 years.
I don't know why the OP said it was critical, but from my perspective it
is critical to determine (to the best possible degree) the cause of
EVERY aircraft accident because every aircraft is subject to unexpected
mechanical failure through a common mechanism. Ruling mechanical failure
ensures the safety of the remaining fleet of that type aircraft.
Five isn't exactly a huge number given the number of airplanes flying
and the number of miles they cover. And I don't consider the failures
due to improper maintenance to be a structural failuer, but rather human
error. I don't consider it a structural failure when a pilot gets into
a dive and then pulls up too abruptly and sheds the wings. That is no
more a structural failure than is a car driven into a tree.
Yes, pressurizes airplanes tend to have a higher incidence of structural
failure. However, since the topic was cars, a much better comparison is
to small private airplanes and for them structural failures (other than
those that are pilot induced) are very rare.
No, all airframes don't have a specified structural life. Life limits
on airframes is a fairly new certification requirement.
I've been to several car wrecks caused by ball joints that came apart,
tie rod ends that came apart, spindles that broke, even a couple of
frames that failed due to rust. Structural failures on cars happen all
the time, you just don't hear about it as with airplanes.
Which aircraft engines? Turbines? Most piston engines, at least from
the big two, aren't much different than they were 50 years ago. They
still use two valves per cylinder, run at low RPM, have low compression
ratios, use magnetos, have manual primers, have manual mixture controls,
no engine control computers, etc. There are a few systems in the works
and a couple aftermarket sytems available, but they are a good 20 years
behind the auto makers.
But why is this more critical for airplanes than for cars?
I think he was talking about severity vs. likelihood of such a failure,
Matt - a distinction that you yourself allude to later in your post. In
that sense, I think he is right to say that aircrfat are more vulnerable
to such failures.
Of course severity of a critical part failure is much more sudden and
unrecoverable in a helicopter. When I was a captian's driver for a
captain over several Navy flight training bases in the early 70's, I
personally witnessed the results of the failure of a blade coupling on a
small Bell trainer helicopter (can't recall the model - much smaller
than a Huey). That's the single piece of metal with concentric
diameters that the individual blade attaches to and rotates about in its
cyclic and collective adjustments. When it suddenly failed about 300
feet off the ground as the student was practicing an autorotation, of
course the blade flew off, and the imbalance of the rotor with the
remaining blades resulted in immediate disentigration of the chopper
with the result that both instructor (a decorated Viet Nam pilot) and
student were lost. I also drove the father and widow of the instructor
in the funeral procession.
Anyway, as a result of that single accident, the whole fleet of that
model was downed while they investigated. They found cracks forming in
the same part on several of them. Obvious solution (20/20 hindsight)
was replacing all of the couplings, and increasing frequency of
inspection and replacement of those parts. One could argue the thin
line between a design flaw and a maintenance issue on that one - after
all even a good design with conflicting contraints (i.e., weight,
strength, performance, etc.) requires some finite maintenance schedule.
A "bad" design with a given maintenance schedule becomes a good design
with a better maintenance schedule. A maintenance procedure and
schedule could (should?) be considered part of the whole design package
(as in FMEA), so, in that sense, one could consider that a design
failure even though you might calssify it as a maintenance issue - the
difference is academic in this case.
[several examples given by Steve]
And don't forget the DC-10 engine pylon bulkhead-to-wing attachment
failure, which was a maintenance induced failure (American and other
airlines took a shortcut not recommended by the manufacturer in R&R'ing
the engines). 273 persons died on takeoff out of O'Hare in '79, plus
there are other DC-10 crashes suspected to be from the same problem that
occurred before the O'Hare one.
Partly because one plane crash can kill hundreds of people and wipe out
an entire airline and/or manufacturer from liability and traveling
When I buy or rent a car, I can pretty much choose between available
models. Yet if I have to fly a certain route as a memebr of the
traveling public, my choice of aircraft may be limited or non-existent.
When you're in a plane as a commercial passenger, if something goes
wrong, you have very little to do with the final outcome. That is not
nearly the case in a car that you're driving - even if there is a known
safety flaw, you can either compensate for it (say in a vehicle that is
known to flip over relatively easily), or easily choose another
vehicle. Granted, you still can't protect yourself from such a vehicle
that loses control and hits yours. But to me, there is a huge
psychological difference in flying in airplane with unexplained previous
crashes than in a car with a known safety problem - and I think most
people are the same way in that regard. For one thing, right or wrong,
most of us feel we can usually compensate for such situations (avoidance
& prevention practices, etc.). In a plane, we are - quite literally -
along for the ride and have close to zero control once the doors are
closed and the engines are started - very scary with less than 100%
confidence in the machine - not nearly so in a car.
As a result of the Delta DC-10 crash, Delta had to be sold off even
though they were 100% innocent on the cause of the problem (their
maintenance procedures were not followed).
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")
OK, but to me the phrase "vulnerable to" implies a probability of
occurence, not the consequences of the event. No doubt that the
consequences of most airplane structural failures are far more severe
than most auto structural failures, unless the failed tie rod end
swerves you into an oncoming semi.
I don't recall a Delta DC-10 crash? When and where? Delta only
operated DC-10s for a short time in the early 70s and then again for a
short time when they inherited Westerns fleet in the late 80s.
I don't know about that. In my mind, "vulnerable" is too general a term
to say whether it implies probability/liklihood of occurrence or
severity/consequences. At minimum, it is ambiquous. Taken at face
value, without him saying which he meant, I would have to agree (or at
least would not disagree) with MoPar Man's statement "Aircraft are MUCH
more vulnerable to structural failure than cars (as a cause of
Heh! Not that this has much to do with this discussion, but I have
vivid memories as a teenager when on a comping trip with my family, when
seatbelts were just being required on new cars, I was standing in the
parking lot of a gas station on a rural mountain road while our car was
being gased up. Suddenly I heard the screeching of tires and looked up
the road to see a telphone company van coming down the road with both
front tires splayed out (obviously a tie rod had broken and the driver
had instinctively turned the other wheel full out in an effort to travel
as close to straight as he could). Everything was in slow motion. The
van drifted over to the right (towards where I was standing) and hit a
concrete curb and flipped over and traveled another 15 feet or so on its
roof. The funny thing was, both the driver and his fellow telephone
company worker had their seatbelts on, no doubt as newly mandated by the
phone company, and were hanging upside down suspended by their
seatbelts. Can't help but wonder if one or both would have been ejected
or otherwise seriously injured w/o their seatbelts. Like I say -
nothing to do with anything - I just thought it a funny story.
Oops - I meant the McDonnell Douglas DC-10 - I intended to state that
McDonnell Douglas, the manufacturer of the DC-10, had to be sold off as
a result of the lost sales from the publicity of the problem even though
they did nothing wrong. (The airline that owned the one that crashed at
O'Hare in 1979 that resulted in the cause of the problem being
pinpointed was American.)
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")
Well, vulnerable has nothing to do with severity, but only with
susceptibility. Check your dictionary.
I'm not aware of any structural failures of a DC-10 proper (not counting
engines). However, it did have at least one major design flaw that
showed up in the Sioux City accident, but that was a systems failure,
not a structural failure of the airframe. It was a structural failure
of the engine that got it all started though.
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