I should have made the accident part a bit clearer. He may have known a hijacking occured, but without enough details. So, he knew it was hijacked, and he figured the crash was an accident. Only after the second one did the truth surface.

And sure, someone might have thought this up long before and had some training scenarios developed. But up until that point, it hadn't happened before, and noone expected it to. I'm prepaired for quite a few technical scenarios in my line of work, but if someone tells me a server went down, I don't immediatly jump to the conclusion that the server is on fire. It's a possibility I am aware of, but not something I expect.

The consppiracy theories tend to come from crackpots who would try to say the sky is pink if they could. Yes, I personally believe the government does certain things and covers them up for our own public good. But I don't believe the US would stage the destruction of property to justify a war.