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Communication mistakes to blame in July's close call of three commuter planes

Federal air safety investigators have concluded that a series of mistakes in communication led to an error that allowed commuter planes to get too close to each other in late July at Washington's Reagan National Airport.

Two commuter jets on July 31 were directed to take off the wrong way, heading toward a third commuter plane coming in for a landing on the same runway. As a result, the planes briefly lost the required minimum distance for lateral and vertical separation.

Regional air traffic controllers noticed a violent weather system south of the airport on the afternoon of July 31 and suggested a change in the normal traffic flow, which would require planes to land from the north to avoid it. That would mean changing the direction of take-offs, too, but the communication to bring that change about was fumbled, according to a report out Wednesday by the National Transportation Safety Board.

Related: 3 jets in close call never at risk of colliding, DOT and FAA say

The NTSB report says that a regional controller called the Reagan Airport control tower, talked about the planes heading in toward the storm and said, "I was wondering if we could flush them all into one-nine," using the numerical designation for landing on the main runway from the north.

But because of many conversations going on in the tower, the traffic manager who took the call said later that she thought the regional controller said runway one -- meaning operations from the south -- not one-nine. She said she assumed the regional coordinator simply wanted to speed up the pace of runway operations, not switch directions.

Because of her misunderstanding, the NTSB says, tower controllers didn't get the word. Only when they noticed the problem did they divert the incoming plane. The report also says that even though the planes got closer than federal minimums specify, "their flight paths never intersected," meaning they were never on a collision course, as some media reports at the time suggested.

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