I'm not an expert, so I have to go by the chronology in the 9/11 commission report. I also don't know why the jets were scrambled out of Langley rather than Andrews; Langley was closer to the tracks of flights 77 and 93, but the controllers didn't know that at the time. We must also consider the likelihood that there are parts of the response, particularly the defense of Washington, that were in the classified portion of the report.
NORAD was notified Flight 77 had been hijacked, and of its approximate location, only four minutes before it hit the Pentagon. So if there was any failure on the morning of 9/11, it was a failure on the part of the FAA to do something it was never designed to do.
The more important failures were in anticipation and planning, which goes back to the acknowledged failures of intelligence.
You make some solid points. Thanks.