According to French investigators, Air France pilots who reported their Boeing 777 was failing to respond while preparing to land earlier this month simultaneously pulled the controls in opposite directions.

After a six-hour flight from New York, Flight 11 was on final approach to Paris Charles de Gaulle airport with 177 passengers onboard when the landing was unexpectedly canceled on April 5.

A pilot was overheard in the background yelling “stop, stop” in a radio conversation that was widely distributed on the Internet, and the captain notified the tower that the airliner was “all over the place.”

The BEA aviation accident investigation agency in France stated in a preliminary report that the two pilots “simultaneously made inputs on the controls” during a go-around for a second attempt.

The agency has classified the event as a “serious incident”, an industry term meaning it could have resulted in an accident.