Standard operating procedures for dealing with hijacked airliners were not followed on September 11, 2001 because earlier in the year -- on May 31, 2001 -- Secretary of State Donald Rumsfeld created a sweeping change in those operating procedures which, among other things, required his prior authorization before military fighter interceptors could be scrambled.

Read David Ray Griffin's "Debunking 9/11 Debunking" (first chapter) for an up-to-date analysis of air traffic control on 9/11.  The failure of North American Air Defense (NORAD) to step in on September 11, 2001 is unprecedented.  Even the Port Authority had its own defense helicopter to man WTC airspace, and yet nothing was done to prevent the "attacks."

In the first few days after 9/11, the military admitted that NORAD did not act until after the strike on the Pentagon at 9:38, although it was at 8:15 that morning that Flight 11 was known to be in trouble. Interceptions usually occur in 15 minutes, but on 9/11 more than 80 minutes elapsed before any fighters were even airborne. This suggested that a “stand-down” order had been issued.  Subsequently, in Vanity Fair magazine, the NORAD recordings were showcased and analyzed, putting the blame was on the FAA to divert attention from the high plausibility of a military stand-down order. This new story has been widely accepted.

Let's not forget that SOPs (standard operating procedures) work flawlessly 100 or more times a year -- fighter jets being scrambled within minutes of any sign that anything at all is wrong.  In addition, military war games or practice drills were being conducted on the morning of 9/11, using many of the fighter jets that would have otherwise been available at air bases throughout the Northeast.  Some of the war games involved airliners being flown into buildings!  The odds that a real event should occur in exact mimicry of a drill or exercise are 1-in-1-with-40-zero's-after-it, a number too huge to have a word for.  See Alex Jones's Terrorstorm DVD about false-flag (state-sponsored) "surprises."