A woman who was looking for the restroom mistakenly opened the aircraft’s emergency exit while the Pakistan International Airlines (PIA) plane was still sitting on the runway. According to a report from Gulf News, Flight PK 702 from Manchester to Islamabad was evacuated after the incident, causing a seven-hour delay. The carrier said it was investigating the incident further.

“As per standard operating procedure, the PIA had to offload nearly 40 passengers and their luggage,” said a PIA spokesperson while speaking to reporters, according to Gulf News.

The aircraft in question is reportedly a Boeing 777, and the incident will set the airline back several thousand dollars to refit the emergency exit with a new inflatable slide. In 2016, a disgruntled flight attendant for United Airlines deliberately opened an emergency exit on a Boeing 737 while the plane was still on the runway. That incident cost United upwards of $30,000 in repairs, reports Business Insider, and the aircraft was out of service until work was complete.

Luckily, the incident in Manchester seems to be a result of confusion, not aggression. However, just one month ago, a passenger on a Ryanair flight went berserk during the trip and threatened to open a cabin door while in flight. However, before he could get to the door, several passengers tackled the man and held him down until the aircraft could land.

“I will literally fight every one of you and kill you and don’t think I’m joking,” the would-be door opener said during the incident, according to a report from USA Today. “I will kill every one of you.”

Have these incidents forced the airline industry to re-think cabin door security? The answer to that question is unclear. However, experts say that opening an aircraft’s cabin door while in flight is nearly impossible.

“While the news never fails to report these events, it seldom mentions the most important fact: you cannot — repeat, cannot — open the doors or emergency hatches of an airplane in flight,” wrote author and airline pilot Patrick Smith on his website Ask The Pilot. “You can’t open them for the simple reason that cabin pressure won’t allow it. Think of an aircraft door as a drain plug, fixed in place by the interior pressure.”