Where was the airforce ?

[mstram]

I have not seen anything on t.v. or read anything online that mentioned the presence of any military jets.

This seems strange to me. After losing comm with ATC, and seeing wild deviation on radar / lost on radar, would the mil / SAR .. etc not be alerted ?

[Mr McGoo]

As a former fighter pilot I can tell you that the only way succesfull intercepts would have been carried out is if armed fighters were sitting on alert ready to go at the first sign of trouble. That only happens when they know that 'trouble is a coming'. Unfortunately the US was caught with its pants down. The failure was not because the fighters weren't ready but because intelligence failed to see it coming.

[Flap 5]

There have been a lot of questions like this asked by the general public and by the media. I am sure that they are asked with genuine ignorance, but just a little common sense would tell you that fighter jets would be ineffective.

Many attempts would be made to contact the aircraft concerned by ATC and it would not be possible to know their final destination until it was too late.

If you saw the video of the first aircraft hitting the Trade Center you see the fireman look up at the low flying aircraft then return to his job. The camera pans left and it was only a couple of seconds before impact that the realisation dawned of what was happening.

It has also been said that the White House has anti aircraft missile defences on it's roof. Even if an aircraft the size of a 767 was hit several times it would continue on its crash course.

[recceguy]

Time is the only issue in this matter.

If you roughly know where the bad guys will be coming from, and if they will be low-level or high-level intruders, you can design a decent system (sorry, I will not give numbers)
If you need to expand the scope of your watch, still with a short notice capability, it will be hugely costly... in fact it used to be done up to ten years ago in our world, and is still done in some specific parts of the World.
Once again, it will depend of the perceived threat.
But airliners being hijacked after their take-off, from an airport close to the intended target.... big challenge (it's a basic story of minutes, nautical miles and knots)