I agree to disagree,
Kimpossible
But, after reading
Pierzin's post, I'll add a bit. I’m curious what people would have said prior to 911 if the Air force professed to paying millions upon millions to make certain that their pilots were perfectly able to take out plane loads of passengers should they ever encounter a hijack situation. Actually, I'm pretty sure I already know the answer.

I asked Mr P to give his input on some of this. Here is what he told me:
QUOTE
There are two types of aviation- instrument flight rules (IFR) or visual flight rules (VFR). Below is a description of each.
IFR- The vast majority of commercial aviation is conducted under IFR. All flight above 18,000 feet must be IFR. In simple terms, IFR flight combines procedural and radar means to separate aircraft preventing mid-air collisions. Under the IFR system the pilot must file a flight plan and receive a clearance for the flight plan before flying IFR. There are several ways to navigate IFR:
1. Federal Airways. These airways are 8 nautical miles (NM) wide, and although pilots strive for the centerline, the equipment on the aircraft does not need to be calibrated to perfection. It is easily possibly to be several miles off course, and be well within the airway.
2. Radar vectors. The air traffic controller simply gives the pilot a heading to fly. The pilot is not supposed to correct for any winds (which at altitude can easily exceed 100 knots) therefore, although the pilot may fly the heading precisely, the radar controller may have to watch the display to determine the effects the winds are having on the ground track.
3. Proceeding to a fix. The controller may tell the pilot to proceed directly to a fix, which is really just a point over the ground. Not all aircraft have the systems required to plot a course directly to the fix that can compensate for the winds. In these cases the pilot points at the estimated location of the fix (which may be not very precise) and then corrects for winds by trial and error. There can be very significant errors in this manner of navigation.
It is quite common for an aircraft to be several miles off course, and no one is alarmed. The primary function of air traffic control is to separate aircraft, not monitor every aircraft to see if it is slightly off course (at 500 mph a few miles may be slightly off course).
VFR- If IFR flight gives pilots some latitude to be off course, VFR is a whole new ball game. In fact, there is no course for VFR flight-pilot’s need not even file a flight plan to fly VFR. In the US pilots may fly VFR below 18,000 ft. with the following main restrictions.
1. Avoid restricted and prohibited areas. These are typically military live fire bombing ranges and important places like the White House. Many of these restricted areas have a maximum altitude that may be overflown VFR below 18,000 ft.
2. Do not enter controlled airspace without clearance. There’s a lot of different types of controlled airspace but to simplify things consider controlled airspace to be around metropolitan areas and airfields with control towers (this is not a pure definition, but close enough). Again, nearly all of this controlled airspace can legally be overflown VFR. For example, Las Vegas may be overflown VFR above 9,000 ft. on any routing and without consulting any controller whatsoever.
Mr P also mentioned something called an ADIZ. This is the zone that NORAD is responsible for the defense of (or was, prior to 911). It stands for the Air Defense Identification Zone. Rules are imposed to identify and track all aircraft penetrating or operating within the
ADIZ. NORAD is not responsible for domestic flight interdiction, except under the most unusual circumstances. The assertions and quotes that Thompson uses to affirm his conclusions the airliners are “intercepted all of the time” are taken out of context, and refer to this zone (“rocking wings, interceptions, ect”). Rules for the ADIZ, and the mission of NORAD, has changed since 911. All in all, it isn't the least bit surprising that fighters didn't scramble within 15 minutes to intercept airliners which they were not cleared to intercept, and were out of their jurisdiction. They followed the protocol at the time. The immediate "scrambling of jets" if the plane goes 15 degrees off course during a domestic flight is a complete fabrication or misinformation...and would be inconceivably expensive to impliment. Since I know little about the rest of the timeline, I won't comment, except to add that if one portion is erroneous, the rest should be extremely suspect.
Edited to add: Regarding
Pierzin's quote above from the Canadian media analyst (no doubt as much an expert in aviation matters as my son's nursery school teacher is an expert on the state Health Department)
QUOTE
Canadian media analyst Barry Zwicker summed up on CBC-TV: "That morning no interceptors responded in a timely fashion to the highest alert situation. This includes the Andrews squadrons which...are 12 miles from the White House...Whatever the explanation for this huge failure, there have been no reports, to my knowledge, or reprimands. This further weakens the 'Incompetence Theory.' Incompetence usually earns reprimands. This causes me to ask whether there were 'stand down' orders." ?? On 29 August 2002, the BBC reports that on 9/11 there were "only four fighters on ready status in the north-eastern US." Conspiracy? Coincidence? Error?
Coincidence, error, or conspiracy that there were only four alert jets in the northeastern US, he asks? None of the above. The nation had exactly the number of alert jets it was willing to fund. If it was a conspiracy, it's a conspiracy that dates back to 1997.