[DanUCSB]

I'm pretty certain (as well as you can be in speculation, albeit very logical speculation) that it would have played out like this, had they been able/willing/ordered to shoot them down:

The order is given, and our fighter jocks are good. All four planes taken down well enough, with complete loss of life. Ie, no one to speak from the scene in the forthcoming Congressional hearings. People would go absolutely apeshit about it... think of what happened with KAL 007, or with Vincennes and Flight 655. Multiply that by four (for the number of airliners), and then by infinity (because they were full of Americans), and you have a lowball on the public outcry.

I think it would be safe to say that it would be the biggest outcry against a sitting president in history. If we can impeach over a blowjob, it's a sure thing. We have enough laws on the books that it's certain there's one somewhere that could be construed to make the president's actions declared illegal. So, the president's out, and villified as the worst CinC in history. There's no mention of where those airliners were about to crash into, because the press is having a field day, and no one can prove it anyway (al Qaeda, seeing the reaction, would -deny- that they were hijacking them as weapons, because the public outcry over the shoot-down would suit their interests just fine). The military gets a bad name as warmongers, and everyone hates the government even more.

Far-fetched? I don't think so. Seeing how the press (and consequently, public opinion) treats a couple prisoners with underwear on their heads? A disaster. Damned if you do, damned if you don't.

Now, all that said, I don't think it would have been a bad course of action. I'd rather sacrifice the career of an innocent president than the lives of 3000 people. I'm just pointing out, though, that if we -had- shot down the planes, the resulting shit-storm would have been huge.