So, It Happened Fast

So now they know for certain that AF447 plunged fast! There's a school of thought that the plane glided almost-imperceptibly downwards through the turbulent thunderstorms, and that the passengers might not have noticed the downward trajectory, but 11,000 feet/minute (125 mph) seems pretty extreme. I don't buy the argument that the passengers didn't notice. It may have been a gut-wrenching free-fall for everyone, even if the plane's attitude was still 'nose-up'. You can't go from level flight to a 125 mph fall in a few seconds without noticing something, even if the falling sensation abates once terminal velocity is reached. Even the sleeping would be awakened by that!:

The initial findings also showed the captain was out of the cockpit for a routine rest period and arrived more than a minute after the emergency began.

The plane was passing through bad weather in the mid-Atlantic when the problems began.

More than eight minutes before the crash, the co-pilot at the controls, one of three members of the flight crew, advised the cabin crew "you should watch out" for turbulence ahead. He said the plane could not climb out of the cloud layer where the turbulence was happening because it was not cold enough.

Soon after, the plane's autopilot and auto-thrust shut off, the stall alarm sounded twice and the co-pilot at the controls, 32-year-old Pierre-Cedric Bonin, took over manual control

The plane climbed from 35,000 to 38,000 feet, but stalled and began to fall.

The two co-pilots wrestled with the controls for about 3 1/2 minutes in a bid to stop the Airbus A330 from spiraling into the sea, the report said.

And they seem inclined to blame the pilots too:

Pilots on the flight from Brazil to France were apparently distracted by faulty airspeed indicators, reports the Wall Street Journal. This reportedly caused them to improperly deal with other vital systems, like adjusting engine thrust.

Sources familiar with the plane's black box recordings tell the Journal that the pilots seemed to be confused by alarms they received from the automated flight-control systems as the plane passed through some turbulence. Such turbulence is typical on that leg of the route from Rio de Janeiro to Paris.

The plane is also said to have faced unexpectedly heavy icing, which is known for making airspeed-indicators and other external sensors unreliable.

It appears that, while primary cockpit displays maintained normal function, the crew didn't follow protocol to maintain or increase the thrust that would have kept the plane's nose level. This was because they had trouble sorting out the warnings while also keeping track of essential aircraft functions of engine power and trajectory.

Reportedly, Air France pilots were never trained to handle such an emergency. But, since the accident, Air France and a number of other carriers have emphasized the necessary training.