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

[glen herrmannsfeldt]

John Santos <john at egh.com> wrote:
(snip)
 
>> The pitot tube and the static pressure port are both things the the wise 
>> pilot checks as part of his preflight inspection.
 
> Sure, for a human looking at the gauge, if it's pinned, he'll ignore it.
 
> But JF was talking about an automated flight control system, which means
> the purely mechanical instrument needs to be digitized, which means 
> electronics...

The computer should check that, too.  It isn't hard and just about
everyone knows it needs to be done.  

The question, then, is failure modes that result in two giving close
to the same (wrong) value while not pinned.  It seems to me that
isn't hard to do in the case of ice.  If the heaters failed, that
could cause icing, or it was colder than the heaters were designed for.

I might suggest different heat values for different ones, such that
equal icing isn't likely to happen.  Also, make sure that there
are no common points of failure between the two heater circuits.

-- glen