Planes had been coming northbound up the Potomac River to land on National’s main runway. With the wind shift, it was decided that they instead should approach National from the opposite direction.
Someone failed to tell one of the controllers in the National tower.
As that controller cleared two US Airways commuter jets — Flight 3467 with 70 on board, and Flight 3071 with 49 aboard — in a northbound direction, an inbound plane that had been rerouted after the wind shift was headed south in their direction.
The pilot of that flight — US Airways 3329 with 73 people on board — had just been ordered by the Warrenton controllers to switch to the tower controller’s frequency for final approach.
“He said, ‘Hi, here I am on the river approach,’ and she kind of went, ‘What? You’re where?’ ” said the federal official.
The controller can be heard on a radio recording asking the pilot, “Are you with me?”
Recognizing the problem, the controller ordered the incoming pilot to turn to the right.
Someone inside the tower, believed to be her supervisor, is heard shouting: “Turn right! Turn right!”
The controller ordered an additional right turn, then instructed the pilot to abort his approach.
As the pilot executed the maneuver, his plane was within 82 one-hundredths of a nautical mile of the oncoming plane, or about 1,650 yards, and the difference in their altitude was 800 feet. The combined speed of the two planes, 436 mph, meant that at one point they were 12 seconds apart.
As he turned to avoid contact with the first plane, he came too close to the second plane: 2.07 nautical miles and 800 feet of altitude. Planes are required to maintain a separation of three miles and 1,000 feet of altitude.
The sharp turn averted one problem but created a new potential violation of aviation rules.
The turn was ordered at what is known as the minimum vectoring altitude, the lowest point at which turns are allowed at that stage of the approach.
“Every controller on the planet knows you don’t vector below [it] because you can’t guarantee the aircraft will be safe from the obstacles on the ground,” the federal official said. “They look at every cell tower, every building, every lightning rod, every mountain, and they set a minimum vectoring altitude. This airplane was below the minimum vectoring altitude.”
At one point, the turning plane was 200 feet below the 2,000-foot minimum altitude.
Controllers are allowed to violate that rule in emergency situations, another federal official said.
This is not the first occasion that controllers at National have been involved in controversy. Last year, news of a sleeping controller there led to the revelation that controllers on overnight shifts at several other airports were napping on the job. The FAA suspended or fired several controllers for sleeping on the job, and the controversy contributed to the ouster of the head of the FAA’s air traffic control organization.
Another incident involving National Airport drew attention to errors made by controllers. In 2010, an airliner carrying Rep. F. James Sensenbrenner Jr. (R-Wis.) swerved to avoid another jet when the planes got so close that an onboard collision avoidance system was activated.