The protocols did not contemplate an intercept. They assumed the fighter escort would be discreet, “vectored to a position five miles directly behind the hijacked aircraft,” where it could perform its mission to monitor the flight path of the aircraft.
In sum, the protocols in place on 9/11 for the FAA and NORAD to respond to a hijacking presumed that:
(1) the hijacked aircraft would be readily identifiable and would not attempt to disappear;
(2) there would be time to address the problem through the appropriate FAA and NORAD chains of command; and
(3) the hijacking would take the traditional form, not a suicide hijacking designed to convert the aircraft into a guided missile.
On the morning of 9/11, the existing protocol was unsuited in every respect for what was about to happen. What ensued was the hurried attempt to create an improvised defense by officials who had never encountered or trained against the situation they faced.