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

[David Mathog]

JF Mezei wrote:

> BUT, they found cases where 2 probes failed at the same time and by the
> same magnitude. This caused the remaining one to be kicked out despite
> being correct, and the 2 errorneous ones to be used because the
> differences between them are within bounds. As a result, the aircraft
> used very wrong values for the air sensors.

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.

Regards,

David Mathog