This is the A330/340 FCU (Flight Control Unit) panel. It's placed between the two pilots just below the upper shade rim of the front instruments panel. It has three areas: the two lateral ones are exactly the same, affecting each one at the flight instruments on the PFD (Primary Flight Display) of its side. The central one is common, with buttons and knobs to set APs and A/THR (Auto Pilots and Auto Throttle) on/off, the FDs (Flight Director) mode and other settings, such as altitude to maintain by the AP engaged (curiously, you have to 'push' the 'altitude to maintain' button to level off at it when captured...)

To fly the plane in Normal Law, with one AP and the A/THR engaged (99,99% of the cases), at least two of the three outputs from the three ADIRUs should be valid. In the event there's only one valid, the system considers it invalid too. The consequence is that the AP and A/THR are disengaged, the FDs crossbars disappear from the PFDs, and the flight control law switches automatically to Alternate.

It seems the aircraft, near TASIL intersection on her route, encountered at its FL350 cruising level a 'cloud' of ice micro crystals, quite common in the weather conditions at the area, and not able to be detected in the plane's weather radar. At least two (maybe the three ones) pitot probes ingested some amount of these crystals, and became partially blocked. Their readings became invalid... This led to the facts described in the above paragraph.

What happened then is a matter of Human Factors only... The pitots ice-blocking problem lasted for just 1 or 2 minutes, but led a big airliner to plunge into the ocean in a stall situation, with her nose slightly above the horizon (about 6º pitch attitude), a small left bank angle (less than 15º), full N1 rpm in both engines, and a vertical descent speed of about 15000 fpm!...

Next report when I finished the reading/studying BEA's Final Report .

Have a nice night.

NOTE: To Grasshopper, if you read this. If you understand more or less the meaning of all the above text, you're not completely lost to the Aviation World...

TWRman