As the pilots of Northwest flight 188 overshot their airport and streaked across the sky, controllers in Denver and Minneapolis tried repeatedly to reach the plane. They attempted for an hour and 18 minutes to make contact, calling the airline and other pilots for help.
But one key group was not notified early on -- the military.
Gen. Gene Renuart -- who, as commander of the North American Aerospace Defense Command, is responsible for safeguarding the skies -- said NORAD is usually notified within 10 minutes of an unusual incident.
"I think all of us are concerned that an aircraft sort of goes off the net for an extended period of time like that," Renuart said.
In this case, the notification was so late that by the time F-16 fighter jets were ready to launch, controllers and the Northwest pilots were back in touch, according to the general.
"It's a good wake-up call for us, and I think, in some cases, we have become sort of comfortable with the level of activity, and we have to remember that these things occur with no notice," said Renuart. "We have to be agile and responsive."
When asked if he would have put jets into the air if he had been given more time, Renuart said, "Absolutely, absolutely."
Here's how it should have worked:
Controllers at Denver Center should have notified their FAA supervisor when they couldn't raise the jet.
The supervisor then should have notified the FAA operations center, which sends out an alert over the Domestic Events Network.
That network is monitored by the military, homeland security officials, FBI and scores of other agencies.
The alert did eventually go out, but it may not have been until the plane was flying over Minneapolis, where it was supposed to have landed. That may have been nearly an hour into the incident.
"I think that as soon as you find you can't reach an aircraft carrying, perhaps, several hundred passengers flying over populated areas in the United States, you immediately ratchet it up," said aviation security consultant Charles Slepian of the Foreseeable Risk Analysis Center.
The FAA is conducting an internal review.
In a statement, FAA Administrator Randy Babbitt indicated the controllers may not have been alarmed initially because "the plane followed its flight plan, the transponder remained on and the plane did not send any emergency or distress signals."
However, Babbitt's statement added, "The controllers should have notified NORAD more quickly that the plane was not responding."
The FAA plans to retrain controllers on proper notification procedures when they lose radio contact with an aircraft.
NORAD, too, is looking at its response to see if personnel acted quickly enough once they became aware of the problem with the Northwest jet.
Renuart said that, in the future, NORAD should "launch the airplanes, get them up there and then we'll sort it out later."
Because, he said, after 9/11, you can never be too careful.