Planes can ascend in the air through the delicate forces of thrust and lift, but for that seemingly magic process to occur, you need pilots to be able to get into the cockpit. That’s pretty much the first rule of physics.

Over the weekend, American Airlines passengers in Dallas experienced delays not due to weather or tarmac traffic, but because the pilots couldn’t get in the cockpit. And no, they didn’t forget the keys or anything. 

According to a post on Reddit on Sunday, as passengers were heading down the bridge to pre-board a flight from Dallas–Fort Worth to Monterey, California, the pilot allegedly told them to turn back to the gate.

“Halfway down the bridge for pre-board (husband recovering from surgery) when the pilot comes out and says to turn around and go back to the gate – that they got locked out of the cockpit,” the passenger wrote on Reddit.

“Y’all. They had to call maintenance and get someone to go in through the window to unlock it from the inside.”

Chron reached out to American Airlines for comment and will update the article when we hear back.

The flight was reportedly delayed for an hour and a half as a result, but maintenance crews were eventually able to climb through the window to open the door. It wasn’t locked, just sticking, as doors sometimes do.