Re: Buran Website Finds So Far

Jorge R. Frank wrote:

> Dale <drc@xxxxxx> wrote in
> news:6afga1dppa1obklqf5dkattf7ajih7sl80@xxxxxxx:

>> 34 years without a fatal accident while operating in an environment
>> that few would consider to be a "safety culture" can't just be
>> luck, can it?

Yes, it can. There just isn't the number of flights to make a
statisically significant sample.

> Right. It's not just luck; it's extremely low flight rate. Years
> aren't relevant. 34 years *sounds* impressive, but Soyuz has had
> only 82 flights without a fatality in those years. The shuttle had
> 87 between Challenger and Columbia.
>
> The overall numbers on fatal accidents (2 in 92 for Soyuz, 2 in 113
> for shuttle) and fatalities (4 in 219 for Soyuz, 14 in 672 for
> shuttle) represent a statistical tie. Within the margin of error
> imposed by the small sample size, both vehicles are about 98% likely
> to get you home safely.

More to the point, rather than just quoting the number of fatalities,
it should be noted that crew losses in each accident are 100%. The
only reason that Soyuz hasn't killed more people is that it doesn't
carry more people.
The plain fact is that spacefight is dangerous. It requires powerful,
complicated machines to get you to and unforgiving, hostile
environment. There's no way it's ever going to be as safe as driving
to the corner store.
As to the "Safety Culture" - I submit that thatreally doesn't come
into play, here. Up to this point, neither us or the Russians have
lost spacecraft to simple, obvious problems[1]. Nor have we lost
spacecraft to the same problem more than once. "Safety Culture"
protects you against known failures, and works when problems don't
recur.

[1] "But what about the O-Rings on Challenger, or the Foam Strike on
Columbia?", I hear you say.
That there were problems with the O-Rings sealing properly was known.
But in most cases, the O-Rings _did_ seal properly, and they were
felt to be understood. If launch conditions had been slightly
different, or if the burn-through had occurred on the other side of
the joint, it would have been just another incident to go into the
stack of data.
The same goes for Columbia - While there was concern that the foam
strike (Once it was identified) had damaged to tiles, nobody at the
time was concerned about the leading edge RCC panels. Those were
known to be tough - so tough that when the rain erosion and particle
damage tests were performed early in the program, it was impossible
to damage them. What hadn't been anticipated was the embrittlement
that occurred in the panels after having been flown a number of
times, and the effects of an almost impossible square strike on the
leading edge. (Due to the curvature of the leading edge profile, the
chances of a hit not glancing off are extremely small.) That the hit
occurred in the worst possible locations - where the bow shock
impinges on the wing during re-entry, was the icing on the frosting
on the cake.

--
Pete Stickney
Java Man knew nothing about coffee.
.

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