Air passengers around the world can be reassured that the emergency slides on aircraft work well - too well, if anything.
Or so we found out when an anonymous flight attendant posted photos on Twitter of one that inflated not into the sea or on the ground after a crash landing but into an unsuspecting boarding ramp after an otherwise unremarkable flight.
The images of the slide bursting from the door, squashing the ground crew's equipment, look vaguely comical, and in one of the images posted by @Toughmutter, a smirking passenger can be seen poking their head from above the now-deflated inflatable.
The flight attendant behind the Twitter account, which says she is based in Long Beach, California, said that another flight attendant had sent her the photos.
She said: "It doesn't happen too often. The flight attendant didn't disarm the door before opening, and the second flight attendant didn't crosscheck her so both are to blame.
"If the door had been opened from the outside, the slide would not have blown. Since the attendant opened the door from the inside, the slide was activated."
She said the plane was a British Airways Boeing 787 (British Airways has not responded to a request for comment) and was probably full of passengers having just landed.
"It would have been a super loud pop. Mechanics would have had to put a new slide in place of the old slide. There would have been no alarms, though, as alarms are set off by pilots or flight attendants in an emergency."
It is not the first time, such an incident has happened, though airlines probably wish it was, with the cost of replacing the slide estimated at as much as £13,000 ($A28,160). Pprune.org, a message board for professional pilots, estimates that accidental deployments happen three to four times a year.
Emergency slide deploys on the ground on Alaska Airlines Boeing 737-400 (N778AS) pic.twitter.com/24jDvFStm5— AviationSafety (@AviationSafety) June 22, 2014
Another concern is the force with which emergency slides inflate - experts say getting hit by a raft inflating could cause serious injury or death as thousands of pounds of pressure are released. The slides, made with a tough, rigid material, are designed to be inflated to the point of solidity in less than 10 seconds.
Travel writer Lizzie Porter went on a British Airways staff training course where she learnt that the slide is designed to take 150 people a minute in an emergency evacuation.
She said: "If members of the cabin crew haven't made sure the door is in manual on landing, the slide will inflate in less than 10 seconds, and ground staff on the other side of the 'won't be there much longer'."
Pilot and author of Cockpit Confidential, a book about air travel, said a plane door would not be able to open inadvertently during the flight because of the pressurised cabin, however, it is possible on the ground.
"While the plane is taxiing, you will get the door to open. You will also activate the door's emergency escape slide," he said. "As an aircraft approaches the gate, you will sometimes hear the cabin crew calling out 'doors to manual'. This has to do with overriding the automatic deployment function of the slides. Those slides can unfurl with enough force to kill a person, and you don't want them billowing onto the jet bridge or into a catering truck."
As we've seen here.
The Telegraph, London