The emergency chute from a United Airlines jet was deployed at Sea-Tac International Airport Wednesday, NBC News reports, delaying the flight.
United 856 had not departed from the gate and no one was injured.
The pilot was the one who accidentally deployed the chute. He was assisting a flight attendant who was unable to close the door to the Boeing 757, according to NBC's Bob Sullivan, who was on board.
The pilot reportedly yanked on the door and caused it to break free from the plane, after which the chute deployed onto the tarmac.
Passengers had to deplane and the flight was rescheduled to take off after 1:00 p.m.
The pilot apologized to passengers over the intercom, according to Sullivan.
"I forgive United for this major delay — mistakes happen," Sullivan said. "Now, I wonder if United will forgive me the next time I have to change a flight."
The flight was bound for Newark, New Jersey.