Pilots aboard a commercial jet mistakenly thought someone was trying to breach the cockpit Monday, leading the flight to return to the Omaha airport less than 40 minutes after departing for Los Angeles.

The misunderstanding on American Airlines Flight 6469 came about because the intercom that pilots and flight attendants use to speak to each other had been left on by accident, an American Airlines spokesperson said. The pilots heard some static sound over this intercom and they mistakenly thought it meant someone was trying to break in.

The flight was operated by SkyWest, which flies regional routes for American and other airlines. The plane was an Embraer ERJ 175, according to the flight tracking website FlightAware.

The Omaha Airport Authority said there was no security related incident at the airport and referred questions to American.