Two airplanes narrowly avoided a collision at Austin-Bergstrom International Airport in Texas on Saturday after an air traffic controller cleared the arriving and departing flights to both use the same runway, the authorities said.
A FedEx cargo plane, a Boeing 767, was forced to abort its landing after a Southwest Airlines flight was cleared to depart on the same runway, the Federal Aviation Administration said in a statement.
The FedEx flight, traveling from Memphis, Tenn., was cleared to land on Runway 18-Left around 6:40 a.m. local time while it was several miles from the airport, the F.A.A. said.
“Shortly before the FedEx aircraft was due to land, the controller cleared Southwest Flight 708 to depart from the same runway,” the agency said. “The pilot of the FedEx airplane discontinued the landing and initiated a climb out.”
In an excerpt of radio transmissions of the episode posted on Twitter, an air traffic controller alludes to reduced visibility conditions, said Michael McCormick, a former F.A.A. control tower operator and an assistant professor of aviation science at Embry-Riddle University, which has its administrative offices in Daytona, Fla.
At one point, the Southwest flight is abruptly told to abort, according to the audio excerpt.
Mr. McCormick said the air traffic controller likely could not see either of the two planes, but was relying on both pilot reports and airport surface detection technology to track the planes. He said the near-collision was “exacerbated” by reduced visibility, which can be caused by dense fog or an unusually narrower gap between the ground and clouds.
Mr. McCormick said there was not enough room between the two planes and said they were in a “critical phase of flight in bad weather conditions.”
Mr. McCormick and Ross Feinstein, a former spokesman for both the Transportation Security Administration and American Airlines, said the near-miss appeared to be caused by air traffic control. The union that represents air traffic controllers could not be immediately reached on Sunday.
The Southwest plane landed about three hours later in Cancun, Mexico, according to the flight tracking website FlightAware. It was not immediately clear how many people were aboard. A company representative declined to comment. A spokeswoman for the Austin-Bergstrom International Airport declined to comment.
Shannon Davis, a FedEx spokeswoman, said that the cargo plane, which was coming from Memphis, eventually landed safely in Austin. It was not immediately clear what, if any, cargo it was carrying.
The National Transportation Safety Board and the F.A.A. both said they were investigating.
The episode in Austin came a day after a minor accident involving two United Airlines planes at Newark Liberty International Airport. A Boeing 787 that was being towed clipped the wing of a parked plane, a Boeing 757-200, the F.A.A. said. Images from the scene showed the tip of a wing was ripped off.
No one was injured and airport operations were not affected, the Port Authority of New York and New Jersey said. Passengers were rebooked onto different flights, and the other plane did not have any passengers, a United Airlines representative said. The F.A.A. said it was investigating.
Last month, at Kennedy International Airport, an American Airlines plane crossed a runway about 1,000 feet in front of a Delta flight that was about to take off. The American pilots appear to have misconstrued directions issued by air traffic control, according to radar records and audio recordings.