A frightening report on CNN, whose analyst showed the radar-tracking of each of the four planes, per air traffic control. Each, after traveling a goodly way on its regular, planned flight path, then veered suddenly and sharply. After they veered, two were flying straight toward New York City; the other two straight toward Washington, D.C. Also, the timings were such that (as best I could tell), each pair would reach its target city simultaneously.

If so, it shouldn't take a rocket scientist to deduce from that pattern exactly what was happening. It appears (though not precisely stated) that the pattern was visible about half an hour before impact -- presumably enough time to send up military interceptor-aircraft.

Was this pattern spotted and recognized?