OK .. stupid question
How do you accidentally fly a plane into a building??
It HAS happened before, but always weather related (fog, etc.). A B-25 flew into the Empire State Building in the 1945 due to fog...
The only one that comes to mind was the bomber that hit the Empire State Building in the 40's - but that was due to heavy fog. It's a bright, clear day in Milan, and there are no other skyscrapers right around the Pirelli building.
I don't buy that it's an accident. No freaking way.
First, you must convert to Islam. Then, you must join the Wahabbe sect of Islam. Finally, you must accidently fly the plane into the building on purpose.