The problem on 9/11 wasn't the crashing of the plane, people accept risk in transport -- the deadliest means of transport in the US in 2001 was an automobile -- 10 times deadlier than being a passenger on a plane. The problem was the using the plane as a weapon.

car - 4600 billion pax miles, 42,000 deaths, 1 per 100 million miles

plane - 500 billion pax miles, 246 deaths of airline travellers on 9/11, 265 from Queens, about 1 per 1 billion miles