The Boeing 747 crash-landed in a field on the edge of Hatfield forest, near the village of Great Hallingbury, Essex, and caught fire as it hit power lines. But the cargo plane landed in a sparsely populated area and there were no reports of any casualties on the ground.
Hundreds of travellers beginning their Christmas break were left stranded at Stansted airport, which was immediately closed. Commuters faced gridlock on surrounding roads, including the blocked M11 motorway, and there were local power cuts.
Witnesses reported a vast orange fireball, and debris was seen falling on to roads and the surrounding areas. Essex fire service battled to deal with a fire in the plane and several isolated fires in the field in which it landed.
The plane took off from Stansted at 6.31pm on its way to Malpensa, near Milan, Italy. Two minutes later it crashed about a mile away, near the A120.
The cause of the crash, which killed three crew and a maintenance worker, was unknown last night. The airline has a chequered record and is known as one of the world's worst carriers for safety. Last night's incident was the fifth crash in 12 years.
Experts from the air accident investigation branch of the department of transport will hold a full-scale investiga tion of the crash and report directly to John Prescott, the environment and transport secretary. Air accident investigators rushed to the scene last night to begin their inquiry.
Mr Prescott spoke to the prime minister, Tony Blair, within half an hour of reports of the crash and will visit the scene today.
Korean Air, the world's second biggest cargo airline behind the US-based Federal Express, began its Stansted freight operation this year.
David Learmount, an aviation expert, said last night the airline had been undergoing a "safety crisis" in weeks preceding the crash.
Some air crew were suffering "appalling morale", he said. "There have been many former military pilots who were fast-tracked to get right to the top. Many were arrogant and believed they knew it all. This had led to problems with the civilian pilots who were not in the fast track.
"Most of the crews are being retrained by the Americans who are trying to inculcate a safety ethic in an airline which clearly didn't have one."
In August 1997 a Korean Air Boeing 747 on a flight from Seoul crashed in Guam, killing all but 26 of the 247 passengers and crew on board.
Conditions at Stansted last night were wet and drizzly, with wind at an unremarkable 21mph.
One eyewitness, Nick Relton, told Channel 4 News: "I was driving to Stansted airport to meet a friend of mine and I saw an aeroplane take off from Stansted.
"I looked again a couple of seconds later and thought, 'where's that plane gone?' and as I thought that, there was a huge orange explosion, flames leaping probably 500ft-600ft in the air. I've never seen anything like it."
Ian Pogue had just come off the M11 to the airport when he saw "a huge ball of red and orange flames. It seemed to last for about five seconds. It just went boom".
Another eyewitness, Andrew Smith, who lives nearby, told BBC radio: "There was a huge fireball and a massive explosion. My whole house shook. Suddenly all the lights in the area went out, the whole sky was lit up."
Joseph Tranter, a farmer, described how he looked into the sky to see the plane "explode like a giant firework". He said: "Once the plane came down, a big mushroom cloud erupted into the air like a bomb had gone off in the forest. There were flames leaping up about 300ft into the air - it was an absolute inferno with debris showering everywhere."
Some inbound passenger flights to Stansted were diverted to Luton and Heathrow airports.
More than 100 emergency vehicles attended the crash scene, but the main hospital for Stansted, the Princess Alexandra hospital in Harlow, nine miles away, said it was not expecting to receive any casualties.
Kay Hoare told Sky News: "We just heard a very loud bang and a bright light in the sky and then sparks."
She said it appeared the plane had been taking off when it crashed in fields between Great Hallingbury and Little Hallingbury near the A120.
Another witness, Lawrence Waite, watched from a mile away. "I couldn't see flames from where I was but there is lots of smoke in the air. There were lots of blue lights and red lights. It seemed like chaos."
Stansted is the third biggest freight airport in the United Kingdom after Heathrow and Gatwick, handling more than 200,000 metric tonnes of freight a year.
