Will we ever know what happened with NORAD? What did go wrong? Are you at liberty to say? I have read several different accounts, along with what tinfueled stated, that NORAD was ordered to stand down. I also read the missile alert system at the Pentagon wasn't operating!
It is hard to know what is true and what is fabricated.
The 9/11 Commission was a partisan farce!
The Air Defense Sectors operated on an ancient system call the AN/FYQ-93, or the Q-93. The only way to detect a hijacked aircraft was for operators to be zoomed out far enough to notice the little symbology for a hijack squawk (transponder mode 3 code of 7500). The hijackers turned off the transponders within 5 minutes of taking the cockpits, and not all of the planes' pilots ever rolled the transponder codes to 7500.
In that era, we didn't track flights that were over the continental US/Canada, and regarded US/Canada originating air tracks as friendly by origin. Our mission was directed outward toward the former Soviet Union. We would drop all friendly air tracks from the scope once they were over land, to avoid cluttering up the picture and overloading the system with data.
In today's world, the modern systems can store multitudes of more data without crashing, and we have alerts displays that let us know if a transponder is squawking an emergency code anywhere in radar coverage, regardless of whether its within our area of responsibility. I'll click on my alerts numerous times per shift only to find myself looking at an air track flying (or more commonly, on the ground, testing its codes) over Florida, North Carolina, or NY, which aren't in my area of responsibility, and simply click back to where I was.
With this ability, I can easily initiate a symbology, report it, take switch actions upon my symbology so that we never lose data or tracking continuity, even if the data fades from radar coverage.