Hi Ken:
> The Forrestal incident occurred during the Vietnam conflict, July 1967. It
> was pretty much as you describe except I would not say EMI was not
> controlled. All DOD services had EMI requirements at his time. In fact,
> 1967 was the year that MIL-STD-461 was adopted as a Tri-Service requirement
> superseding Service-unique standards. The actual mechanism was that a
> shield termination on a pyro actuation circuit on one fighter was degraded
> or broken and radar illumination of it fired a weapon inadvertently, into
> another fully loaded, and fully fueled fighter. That was the cause of the
> disaster. In September 1967, MIL-E-6051C, Aircraft EMC was updated to the
> "D" revision. In "D", for the first time you have 20 dB safety margin
> demonstration on pyro electrical actuation. Coincidence?
A colleague once said:
"Safety standards are the inversion of
bad experiences."
Your story confirms this approach to safety.
For commercial aircraft, especially since
September 11, we can also say:
"Security standards are the inversion of
bad experiences."
The trick, of course, is to anticipate the
bad experience so as to prevent it in the
first place. FMEA (Failure Mode and Effects
Analysis) and FTA (Fault Tree Analysis) are
two process by which some specific bad
experiences can be anticipated.
We don't have a process by which all possible
bad experiences can be anticipated.
Speculation as to either the bad experience
itself or the probability of the bad
experience is often pooh-poohed by those who
would either implement the fix or authorize
implementation of the fix. In the absence of
data, prevention of a speculated bad experience
is unlikely, no matter the ultimate validity of
the speculation.
As I recall, the issue of this thread is that
of anticipation of an RF signal causing a
"bad experience" by "mal-operation" (not a
mal-function) of an equipment. Today, we
simply don't have processes by which we can
test equipment for RF-induced bad experiences.
So, we argue both sides without a conclusion.
Hopefully, through such arguments, some of us
may get an idea of how such anticipation can
be implemented.
Best regards,
Rich
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