The latest speculation I heard was that the pilot may have been trying to hand-crank the landing gear down (an emergency procedure), which involves some fancy cockpit contortions. This would require him to "take his eyes off the road" while he was doing it. It's also speculated that he didn't hit the building straight-on, he came in at an angle, which accounts for the wide, horizontal hole in the building.

Few real facts known at this point, but the media is having a real orgy speculating about what might have happened. A classic example of Firth's formula:-- News Media + Lack of Solid Information = Sufficient Volumes of Gas to Turn Earth into a Jupiter-like Planet.

Don Firth