A couple had a near-miss with a falling door from a British Airways passenger plane while taking a walk in Surrey, an accident report shows.
The report recommended a review of BA maintenance procedures
A large part of a 32kg (70lb) door came away from a Boeing 777 because it had been inadequately fastened, the Air Accidents Investigation Branch found.
It landed just six metres from the couple, shortly after take-off from Gatwick Airport on 26 June, 2003.
BA said it had reviewed its maintenance procedures and had made changes.
There were 272 passengers on board the plane at the time of the incident.
Some cabin crew reportedly felt "a thump and heard a loud bang" after the door detached.
Fragments of the underwing access door came into the passenger cabin and caused substantial damage to two windows.
The report from the Air Accidents Investigation Branch (AAIB) said that despite extensive checks by aircraft personnel, it was likely that only one of the door's 13 catches had been fastened.
It added that the falling door was "not only a hazard to those on the ground but it also had the potential to hazard the aircraft".
"The inadequate fastening had apparently occurred during a routine maintenance check due to a deviation from standard procedures; a practice that reportedly had been fostered by features of the maintenance system and may have been commonplace," the AAIB report said.
Crew were forced to fly the plane back to Gatwick following the incident, where it landed safely.
A dark-blue 2-inch square item was found inside the cabin, which was then passed to the cockpit crew.
Debris lying in a wooded area near Reigate, Surrey, discovered by a dog walker, was identified as part of the missing door.
The report said a large portion of the door "was found when a couple who had been out walking described having seen it fall nearby after their attention had been drawn by another substantial part of the door impacting the ground around 20ft from them".
A spokesperson for BA said the airline carried out its own investigation following the incident and made a number of changes to its maintenance systems and procedures.
"We cooperated with the AAIB throughout the investigation and note the new safety recommendation contained in the report," British Airways said.
"The safety and security of our operation is our top priority and we will study the report in detail to ensure that we learn from what was a very rare and unusual event."