A packed American Airlines jumbo jet and two military C-17 cargo planes avoided catastrophe, after they were mistakenly sent to the same altitude by controllers at New York's Air Traffic Control Center. The planes -- both closing in on 22,000 feet -- came less than a mile from each other horizontally, and 200 feet vertically. A collision alarm in the cockpit of the American Airlines Boeing 777 sounded, warning pilots to descend. They did, averting a possible collision.
The close call occurred at 10:30 p.m. on Jan. 20, about 80 miles southeast of New York City. The incident is now under investigation by the National Transportation Safety Board.
The American flight, with 259 passengers and crew, had taken off from New York's JFK airport, bound for Brazil. According to the NTSB, the jet was flying in a southeast direction. The two U.S. Air Force C-17's were flying northwest, toward McGuire Air Force Base in New Jersey.
Aviation sources tell ABC News that the controller directing the C-17's asked the controller handling the American flight to hold the flight at 20,000 feet, but that controller was busy with another jet and missed the request.
As both planes headed to 22,000 feet, the C-17 controller realized what was happening and again asked the other controller to stop the American Airlines flight from climbing. He then directed the military pilots to hold at 22,000 feet. But the other controller, hearing that instruction, thought the 22,000 altitude instruction was for the American flight – and sent the Boeing jet to 22,000 feet as well.
"The impact of a breakdown in communication can be very serious," said former air traffic control manager and safety consultant Dick Marakovits. "In this circumstance, technology stepped in within the aircraft and saved the day."
The Federal Aviation Administration says controllers at New York Center have all been required to review procedures in the wake of the near-miss.
Marakovits says the system works well overall. "Each aircraft under control within the New York center receives about 8 or 10 air traffic controlled instructions per flight. Times 8000 airplanes, that 80,0000 communications a day. Can there be difficulty, can there be miscommunications/misunderstandings within those 80,000 discussions? Yes there can be. The system works pretty well, though, given those dynamics."
In the incident in January, the planes got so close the error has been categorized by the FAA as a level "A" operational error – the most serious kind. The FAA says so-called operational errors, when planes get closer than allowed, are rare. In fiscal year 2010 there were 1,889 operational errors. Four hundred and forty-five of those were labeled "A" or "B" events – the two most serious categories. Just forty-four were considered level "A", The FAA says that is out of more than 133 million operations.