Do you honestly think that the airline industry--and the public--would have put up with being put on high alert for two months, in the pre-9/11 world?
I think that when you know that Al Queda is looking to use airplanes against America, you don't give the airlines or the public any choice for godsake! Explain the dangers, and people, most people anyway, will take those dangers seriously. This happened toooooooooooooo fucking easily for the terrorist. You may not be able to plan for the Spanish inquisition, but you sure as hell can conceptualize the 9/11 modus operandi, and if you can't, you probably don't need to be in charge of keeping the country safe.
High alert Schmigh alert, lol. 2 months?? It's just the way we do plane travel now, and it could have been being implemented before. As I said, strong cockpit doors and a strong directive to pilots, and 9/11 does not happen. That doesn't affect the public much, if at all. A ban on carry-on of knives etc, and 9/11 probably doesn't happen, or isn't nearly as successful.
So the terrorist in training at the flight schools slipped thru the FBI chain of command w/o making it to the people who knew to be looking for terrorist and airplanes in the same space...... imagine how much less likely that would be too happen if the public, including the people taking flight lessons with potential terrorist were aware of the threat. Or heck, leave the public out of it, what if the NSA had the FBI chief and the CIA chief in the same room every day, grilling them on what knowledge each had about threats to America? There was good reason to be doing that, givin the level and intensity of threats.
First and formost, the problem needed high level attention, and the people at high-levels were focused on things they considered more important than Al Queda and religious extremist terrorism. Even after 9/11, they chose to split their attention, and our resources, between fighting terrorism and their pet-project from day one, Iraq.