An FAA official familiar with the incident said the command was a last resort when dealing with massive planes like the three involved.
"They don't maneuver like fighter jets," said the official, who spoke on condition of anonymity because he is not authorized to speak for the FAA. "You definitely would not do it to a flight of two heavy jets unless you had no other choice. American got a [cockpit alarm] to descend. That may be what saved the day."
The severity of the incident resulted in an investigation by the National Transportation Safety Board, the federal agency more commonly associated with investigation of plane crashes. The NTSB began reviewing midair near-collisions last year and questioned the reliability of the FAA reporting system.
FAA spokeswoman Sasha J. Johnson said the agency was reviewing the incident.
"As a result of the FAA's preliminary investigation, all air traffic operational personnel at New York Center are already reviewing a variety of procedures, including the handling of formation flights, aircraft near sector boundaries and [cockpit warning] requirements," she said.
The Jan. 20 incident involved an American Airlines plane that had just taken off from John F. Kennedy International Airport for a night flight south to Sao Paulo, Brazil. The two Air Force cargo planes were on a northwest course, beginning to descend to land at McGuire Air Force Base in New Jersey.
The near-collision occurred about 80 miles southeast of New York City, after responsibility for the American Airlines flight was handed off to controllers responsible for managing planes at cruising altitude.
In control centers directing planes at that altitude, responsibility for each geographical sector is divided between a controller who watches the radar and one who monitors data coming from all aircraft in the sector.
The American plane had been instructed to climb to 22,000 feet. When the data controller saw a potential for collision he asked the radar controller to halt the climb at 20,000 feet, but the radar controller was distracted by information coming in from a Continental Airlines flight and did not hear the message, official records show.
Unaware of the imminent collision, the American flight continued to climb until its cockpit alarm went off, records show.
Two FAA reports said the planes came within 2,000 yards. The NTSB review said radar showed the distance was closer to a mile. Though in most instances controllers are required to keep a minimum of three miles and 1,000 feet of altitude between commercial planes, FAA regulations call for a greater distance between planes flying in proximity to military formations.
The NTSB is investigating almost a dozen midair near-collisions that have occurred nationally since it mandated in March that they be reported. They include an incident 24,000 feet over Maryland on March 25, when a Continental Airlines 737 came within about a mile of colliding with a Gulfstream jet.
Nationwide, air traffic controllers committed 949 errors in fiscal 2009, a number lower than in the previous year, when there were almost 7 million fewer flights. But the number of errors for fiscal 2009 is significantly higher than in fiscal 2007, when there were almost 10 million more flights.