It is the moment every pilot trains for, yet the chances of it happening are a million to one. The likelihood of a double engine failure on a modern aircraft is overwhelmingly remote but, when it happened over Heathrow on a winter's day two years ago, what could have been the airport's worst disaster was averted due to nothing more than a split-second decision by the captain.
In his first interview since the crash, Captain Peter Burkill last week recalled how he didn't even have time to warn the 136 passengers on board to adopt the brace position as he struggled to land a plane with unresponsive controls.
It was January 17, 2008, and Flight BA038 had almost completed its uneventful 12-hour flight from Beijing when things started to go catastrophically wrong. In the cockpit, the rooftops of central London and iconic bridges of the Thames had just come into view when Captain Burkill discovered that his Boeing 777 was dropping faster than it should.
At 12.41pm, two miles from the runway, his co-pilot John Coward turned to him and said: "Pete, what's it doing? I can't get any power."
As the plane surged downwards towards the busy A380 motorway within touching distance of cars, drivers ducked in terror fearing it was heading for them.
Then, in a flash of inspiration, Captain Burkill handed controls to his First Officer and tried to change the position of the landing flaps on the wing. This vital tweak had a life-saving effect, prolonging the plane's descent by 51 metres and giving it precious time to make it over the perimeter fence of the airport by a whisker.
The aircraft's 12 wheels slammed into the boggy turf beside the fence, the force of impact tearing its fuselage and engines away and sending them scraping along the grass.
In the cockpit, Burkill mentally prepared for his death and said goodbye to his wife Maria in his head.
"When we hit the ground, I became a passenger. At that point, I thought I might die," he said in his recent interview.
"There was not enough time to pray and I don't think I would have done. I recall expecting to hit something and the aircraft go up in a fireball. I was aware the landing was heavy and I thought the tail would have broken off. I still expected fatalities."
But back in the cabin, passengers had barely noticed anything was awry until the plane slid to a stop and cabin crew wrenched open emergency doors, triggering automatic slides.
In the most serious incident at Heathrow for 30 years, just a handful of people suffered injuries, the most serious of which was a broken leg.
This week, the final investigation into the crash concluded that a build-up of ice had restricted the flow of fuel to both engines, causing the aircraft to lose control and fall to the ground.
After the crash, Captain Burkill took voluntary redundancy and has yet to secure another job with an airline. A recent rejection letter claimed that because his CV showed he had piloted a plane that crashed, he would not be hired.
Today he's a motivational speaker and, with wife Maria, is writing a book, Thirty Seconds to Impact, about the far-reaching effects it has had on them and the long nights they lie awake in tears imagining what might have been.