"Jan Panteltje"  wrote in message
news:puri48$gf7$1@dont-email.me...
> Also as to airspeed it should use at least 2 sensors and do arbitration
> and disable itself and give a clear
> warning to the pilots if an abnormal condition occurred.

If you want to be sure, you need at least three sensors and a majority vote
to determine, not that that there is an anomaly, but *which* sensor is
anomalous and should be ignored. Error-correction as well as
error-detection.

I read a very good aeroplane-based thriller. A plane started climbing and
diving, causing a lot of injuries (and a LOT of puke!) and a few deaths. The
airline company needed to preserve its good name and find out as fast as
possible what had happened, amid accusations that there was a design fault.

The pilot and all the aircrew buggered off to their home country as soon as
they landed, so they couldn't be interviewed.

Analysis of the black box showed some anomalous readings for a sensor which
detected the position (retracted/extended) of the slats, and gave a warning.

After a lot of testing, and a very dramatic demonstration to a
trouble-making news reporter, they identified what had happened:

- a duff OEM (fake!) sensor had given a false warning; there was only one
sensor, so no "best of three" was possible

- the plane was on autopilot, but the pilot tried to override the autopilot,
in the mistake belief that the autopilot was wrong and he was right

- the pilot who had control of the plane at the time was the real pilot's
son who was not approved to fly that type of plane but was allowed to take
control at quiet times

- a test pilot from the company was able to provoke the problem by doing
what he suspected the pilot had done, and demonstrated that all he had to do
was to let go of the controls, and the autopilot immediately corrected
things and resumed level flight

Result: company vindicated, reputation intact.

--- SoupGate-Win32 v1.05