At 4:30 p.m. PT, Tuesday afternoon: radio communications between controllers on the ground and airplanes in route go down at the federal aviation facility that controls the separation of planes over much of California, Arizona and Nevada.
"It left us in a situation where we had no ability to talk to 400 aircraft that were under our control," says Hamid Ghaffari, president of the local National Air Traffic Controllers Association.
And 15 minutes later, the system's still down and the back-up system fails.
Controllers start frantically using personal cell phones to ask other FAA facilities to take over. But already there have been five reports of planes getting too close to each other.
In one instance, a Gulfstream business jet flying from Long Beach, Calif., to Washington, D.C., flies only a mile alongside a Northwest flight going to San Diego.
"It was somewhat chaotic," says Ghaffari. "Our job is to separate aircraft and get you home safely and when you take away one element, it can be devastating."
In another case, a Citation business jet traveling from Phoenix to Monterey, Calif., flies within two miles horizontally of a UPS cargo jet — still too close by FAA rules.
"We have redundant systems with our top-notch controllers and systems and everyone rolled with the punches," says FAA spokesman Rick Day.
At 7:30 p.m. PT, three hours after the radios crash, the system's finally back online — but Southern California airports are paralyzed where flights have been delayed or canceled. At Los Angeles International alone, more than 30,000 passengers were affected.
So what caused it all? Human error. Because of a software glitch in an FAA computer, a technician is required to reset the computer that controls the radios every 30 days — something that was not done.
The FAA says they've known about the glitch for a year now — and that it exists at 20 other control centers across the country. Now, the FAA says they'll fix it within a month.