"Doug..." wrote in message
...
| That's a phrase we hear a lot today -- that "everyone should
| have known" about safety issues, about the fragility of the RCC,
| about risks that should never be taken.

This is always the pitfall of hindsight in failure analysis. The people who
argue that someone "should have known" something have the luxury of looking
at the evidence knowing that something failed, and of looking at a
pared-down collection of evidence. Those without the luxury of hindsight
have no way of acquiring this incisive perspective. They do not know ahead
of time that something *will* fail and hence that they should pay close
attention to certain then-innocuous indications. Further, they have the
whole pot of data from every aspect of the system to look at -- among which
may certainly be evidence of impending failure; but there won't be a
flashing light giving artificial salience to that data.

The notion that the potential of mixed-mode or collaborative failures can be
exhaustively predicted for complex systems is simply daft. This was studied
in the wake of the Apollo 13 accident. In a complex system you can discover
single points of failure, and perhaps combinations of two points of failure.
But you cannot exhaustively consider all potential n-way causes of failure.

When we say space travel is inherently dangerous, this is what we mean.

--
|
The universe is not required to conform | Jay Windley
to the expectations of the ignorant. | webmaster @ clavius.org