【海外の反応】9/11でF-16は本当にハイジャック機を撃墜できたのか?武器すら間に合ってなかった説

Not before the first airplane hits the World Trade Center. In the past hijackings had never been about using the airliner as a weapon, so they wouldn't have expected it back then.

Two F-16 did take off to intercept United Flight 93 on 9/11. They didn't have time to arm the planes, they were flying an intercept course prepared to kamikaze the plane. By the time they got there, the passengers had taken control of the plane and crashed it.

It's really impossible to know what decision a superior would have made as it was an unprecedented situation.

I have to think, in terms of risk analysis, the second plane would have still crashed into the other tower because it just wouldn't be assumed that they were on suicide missions and they wouldn't have been shot down. The thinking would likely have been "they're heading to an airport to negotiate a political hostage situation, the first plane crashing must have just been a horrible accident through the crew or individuals trying to fight back."

Only after the second plane would it have then been confidently assessed that these hijackings are suicide missions and should be shot down in situations where it will minimise further loss of life. 

1. They would have needed a reason to shoot down the plane, since in those days a hijacking meant you were taking the plane somewhere and that could be dealt with. So, until the first plane hits the tower, there's no reason for a shoot down.
2. Then it becomes a question of human resolve. The second plane is coming. Has the reality of the situation hit the people in charge? Have they accepted that they need to kill a couple of hundred people? Can they make the call to have a shot-up jumbo jet crash down into the streets of manhattan? It's the trolly problem on an unimaginable scale. Maybe just let the second plane hit the tower? After all, zero people expected the towers to actually fall.
3. I think they would have shot down United 93 if the passengers hadn't forced it down.

So for Flight 11 (the first plane to crash into the WTC) that wouldn't have been a real possibility. A flight attendant was able to alert people that the plane was highjacked at 0819, one of the highjackers unintentionally confirmed it with ATC at 0824, and it hit the building at 0846, 22 minutes later. If there had been a pair of fighters in the area already doing patrols, it's possible they could have intercepted before the building was hit, but at the same time knowing the plane is highjacked and knowing it's target (or intentions, as they weren't really expecting it to be used as a weapon) are two different things. I don't think there's a scenario where anyone with the authority to authorize the attack would have done so before the Flight 11 hit, it's more likely they would have thought the plane was being taken out to sea or something for a ransom instead of completing a suicide mission into a building.

Back to what actually happened, when the report of the highjacking was confirmed two F-15 pilots were ordered to suit up, and at 0846 when Flight 11 hit the WTC they were then ordered to scramble… from Otis Air National Guard Base, about 200 miles from NYC. They didn't get into the air until 0853.

The other plane, Flight 175, took off at 0815 and hit the second building at 0903, 17 minutes after the first. The problem is, that unlike Flight 11, Flight 175 wasn't assumed to be highjacked until 0855 when a controller noticed their transponder had changed and were unable to contact the pilots. I'd say in the theoretical scenario where there were planes already on patrol before Flight 11 hit in the area, it's possible they would have figured out Flight 175 was highjacked quicker and *might* have been shot down before getting into the city. But it's a big maybe.

But going back to reality, the F-15's used afterburner to get within range, but weren't cleared to engage or even enter that airspace due to other civilian traffic. And Flight 175 wasn't even assumed to be highjacked until *after* they were in the air, nearly 10 minutes after the first plane hit. I don't think they could have even downed Flight 175 before it entered the city, meaning it was already pretty much a guarantee lots of innocent people were going to die one way or another, so they were told to hold.