[Info-vax] OT: Aircraft pitot tubes and clustering.

[glen herrmannsfeldt]

David Mathog <mathog at caltech.edu> wrote:
> JF Mezei wrote:
 
>> BUT, they found cases where 2 probes failed at the same time and by the
>> same magnitude. 
(snip)
 
> This could happen if the most common tube failure mode was to take the 
> output voltage to ground or supply voltage.  Then if two failed in the 
> way they are most likely to they will read exactly the same thing.
> Presumably the software should reject readings in these failure mode 
> voltage ranges out of hand, but it might not.

Well, you might hope that they check for that one.

But say two filled with ice at about the same rate, while the
other didn't.  (I think I remembered ice being part of the problem.)
It is a problem of statisical independence.  If there are things
that statistically could happen to both at the same time, then the
test doesn't work.

-- glen