CNN  — 

A Southwest passenger jet and a FedEx cargo plane came as close as 100 feet from colliding Saturday at the main airport in Texas’ capital, and it was a pilot – not air traffic controllers – who averted disaster, a top federal investigator says.

Controllers at Austin’s international airport had cleared the arriving FedEx Boeing 767 and a departing Southwest Airlines Boeing 737 jet to use the same runway, and the FedEx crew “realized that they were overflying the Southwest plane,” Jennifer Homendy, chairwoman of the National Transportation Safety Board, told CNN Monday.

The FedEx pilot told the Southwest crew to abort taking off, she said.

The FedEx plane, meanwhile, climbed as its crew aborted their landing to help avoid a collision, the Federal Aviation Administration has said.

“I’m very proud of the FedEx flight crew and that pilot,” Homendy said. “They saved, in my view, 128 people from a potential catastrophe.”

“It was very close, and we believe less than 100 feet,” Homendy said.

Kirby Lee/AP/File
The near-collision happened at Austin-Bergstrom International Airport, seen here from the air.

Controllers had cleared the Southwest departure from runway 18 Left when the FedEx jet was about 3.2 nautical miles away, she said. Controllers also confirmed to the FedEx crew that it could land on 18 Left when the FedEx plane was 2.19 nautical miles out.

The Austin airport is not among the 35 airports nationwide that use Airport Surface Detection Equipment, or ASDE, to notify controllers of and prevent collisions at airports.

The NTSB in 2018 recommended improvements to the technology and has classified the FAA’s handling of the matter as an “acceptable response.”

That system, Homendy said, played a role in preventing a runway collision last month between taxiing and departing aircraft at New York’s John F. Kennedy airport.

“Air traffic control in this situation can see the FedEx plane on radar. They cannot in Austin see where Southwest is on the ground,” Homendy said.

Correction: An earlier version of this story gave the wrong year for National Transportation Safety Board’s recommended improvements to the Airport Surface Detection Equipment. They were recommended in 2018.