British Airways Flight 5390
The BAC 1-11 is a short-haul passenger jet first flown in the 1960s.
On 10 June 1990, a BAC 1-11 flying as British Airways Flight 5390, was flying at 17 thousand feet over Oxfordshire when the window on the captain’s side of the aircraft burst away, sucking the Captain with it. His head and body were out of the window, and his legs became trapped around the control column, pulling the aircraft into a rolling dive. The sudden decompression ripped the flight-deck door off its hinges, and it fell across the controls.
The co-pilot, Alistair Atcheson, was faced with a 400 mile an hour wind screaming through his cockpit, an aircraft spiralling downward through busy traffic, a door and half a captain blocking his controls, and the other half of the Captain hanging out the window.
One of the Stewards, about to serve the Captain breakfast, instead found himself desperately hanging on to the Captain’s legs to stop him falling out.
Under these rather trying conditions, the co-pilot managed to regain control of the aircraft. He was directed to land at Southampton, an unfamiliar airport. The runway at Southampton was four-hundred metres too short for the type of aircraft, and the wings were still full of fuel.
By this stage another of two stewards had arrived to assist, but the Captain was not moving. They kept hold of him, because even if he was dead his body might damage the wing or engine as it fell. The copilot landed successfully, and the Captain survived.
The physical cause of the accident was depressingly simple. The windscreens on BAC One-Elevens are supposed to be fastened with British Standard A211-8D bolts. On this aircraft the windscreen was accidentally fastened with British Standard A211-8C bolts. The shift manager who had fitted the window made a mistake and used bolts that were too narrow.
If we wanted to be simplistic, we could say that this was a human error by the maintainer, rescued through heroic performance by the co-pilot. We don’t want to be simplistic. We want to understand what caused these people to behave in the way they did.
Let’s start with the maintainer. Instead of thinking about what he could have done differently, let’s consider what else could have been different.
The BAC One-Eleven could have been designed so that air pressure held the windscreen on, instead of needing tightly fastened bolts. The bolt holes could have been designed so that it wasn’t possible to insert and tighten the wrong sized bolts. The bolts could have been designated as safety-critical items instead of just uncontrolled consumables.
The procedure for changing the bolts could have been better designed as well. The maintainer was supposed to consult a database to find the correct part number, but the database was slow and hard to use. The bolts were stored in a poorly-labelled carousel, in a poorly lit area. There was no built in mechanism to check that the right parts were used, or even that the job was done properly.
The maintenance organisation could have been better designed. Shift managers supervised the work of other maintainers, but there was no one to supervise the shift managers when they did maintenance work. The fatigue management system didn’t take into account body rhythms associated with shift patterns. The quality management system was spotting lots of minor part defects, but wasn’t being used to flag major issues.
This was a situation that was inviting, almost forcing maintenance error, and providing no means to detect the error when it occurred.
No let’s look at the air crew, and we’ll start with something so obvious you may have missed it. Passenger jets always have at least two pilots, and they are never short staffed. If one of the pilots is busy handling an emergency, or talking to air traffic control, or hanging out of a window, the other pilot takes over some of the workload. When the first steward to enter the cockpit started suffering from fatigue and frostbite, another steward was there to take over holding the Captain.
Secondly, the crew didn’t hang around asking for someone to tell them what to do. They understood what needed to be done, and they trusted the others to do their jobs too. This is the result of training, experience, and a work environment that fosters teamwork.
The cockpit was designed so that even when a pretty unexpected situation put a number of the controls out of action, there was enough functionality left for the co-pilot to land the aircraft.
None of this takes away from the skill and professionalism of co-pilot Alistair Atcheson. It does show though, that if we want humans to make this sort of contribution, we have to give them the right conditions to make it possible.
