The Federal Aviation Administration said the Alaska pilots aborted their takeoff because the Southwest plane was cleared to cross the end of the same runway.

An Alaska Airlines spokesperson said the pilots recognized “a potential traffic conflict on the runway” and “immediately applied the brakes to prevent the incident from escalating.”

No injuries were reported, but tires on the Boeing 737 Max went flat from the extreme heat buildup during the stop, according to the Seattle-based airline.

The FAA and the National Transportation Safety Board said they were investigating the incident, which happened at about 9:15 a.m. at Nashville International Airport.

Southwest said it was in contact with the FAA and the NTSB and will participate in the investigation.

Alaska Airlines said the flight to Seattle carried 176 passengers and six crew members. The plane was being inspected, and another plane was dispatched to take passengers to Seattle by Thursday night, the airline said.

“We’re grateful for the expertise of our pilots who immediately applied the brakes to prevent the incident from escalating,” the airline said.

A series of close calls, or “runway incursions,” in the last two years raised concern about the safety of U.S. air travel. NTSB Chair Jennifer Homendy said last November the incidents, while “incredibly rare” compared to the number of flights, show that the aviation system is under stress.

Some of the incidents have been blamed on pilots not following instructions from air traffic controllers. However, the scariest of the close calls – a FedEx jet landing in Austin, Texas, flew over the top of a Southwest jet that was taking off on a foggy early morning in February 2023 – was blamed on an air traffic controller’s mistakes.

Thursday’s incident comes just days after two Delta Air Lines planes collided on a taxiway at Atlanta’s airport, with the larger plane knocking over the tail of a smaller regional jet. No injuries were reported.