Instrument Questions

[tcasdescend]

After watching air crash investigation:

Why does the stall and stick shaker warning sound even though pitot tubes are blocked?

Why does the too low terrain warning sound even though the altimeter may be faulty?

If a plane falls down from the sky with the nose pointed up, what will the airspeed indicator indicate?

[sevenstrokeroll]

the stick shaker etc is not part of the pitot system...usually it requires an angle of attack sensor/vane to work

the terrain warning has nothing to do with the barometric altimeter...the earliest forms had a special radar set to measure the angle of the approaching terrain

the airspeed indicator would indicate very low or no airspeed if the plane was falling with the nose up

[ZFT]

GPWS used the radio altimeter for height with no 'look ahead'. It just calculated terrain height closure rate.