[expatpat]

True, the HSI (artificial horizon) would have settled the question if it could be trusted. The gyros can go bad, so you can't automatically assume the HSI isn't lying, especially if the VSI is going nuts, as I understand it was. Plus, the FCS was apparently trying to fly the plane out of a stall, and fighting the pilots.

[az_gila]

True, the HSI (artificial horizon) would have settled the question if it could be trusted. The gyros can go bad, so you can't automatically assume the HSI isn't lying, especially if the VSI is going nuts, as I understand it was. Plus, the FCS was apparently trying to fly the plane out of a stall, and fighting the pilots.

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I don't know the redundancy logic for the AH, but looking at the A-330 cockpit it looks like a separate instrument, even if it is a mini-screen instead of mechanical.

http://www.flickr.com/photos/jpavao/4644756009/

I would have also thought that the Pilots Handbook would give details on which instruments are powered by what for use in emergency situations.

I would also hope that the certification authorities would demand some sort of back-up for the triple redundant computer...:^)

[CFIIIMEIATP737]

“True, the HSI (artificial horizon) would have settled the question if it could be trusted. The gyros can go bad, so you can’t automatically assume the HSI isn’t lying, especially if the VSI is going nuts, as I understand it was. Plus, the FCS was apparently trying to fly the plane out of a stall, and fighting the pilots.”

The HSI is a Horizontal Situation Indicator. It does not give pitch or bank information like an Attitude Indicator or artificial horizon.