It probably started with a spark in a clogged air vent above Burger King's kitchens. Within seconds, flames were licking their way along the web of air ducts in the terminal's roof. In scenes reminiscent of a disaster movie, flames leapt from the top of Terminal One. According to some witnesses, the arcs of fire flew "40 feet up in the air".
But a full-scale catastrophe was never realised. Less than 12 hours after the first alarm at 4.40am, the airport was running virtually normally. Of the 150 people - at least 40 of whom were passengers - who were in the terminal at the time, none were injured.
The airport's own fire crews and the London Fire Service arrived within five minutes of the blaze starting and more than 100 firefighters were involved in tackling the fire.
A British Airports Authority spokesman said the fire had been contained by a pounds 1m fireproof membrane in the terminal roof which had restricted the flames.
Graham Holgate, a Fire Service Divisional Officer, said: "The area of the fire was confined to 200 metres of ducting. Part of the roof was damaged and about 20 per cent of the roof plantroom there was also a certain amount of smoke damage."
Roger Cato, managing director for the British Airports Authority at Heathrow, said the incident would be closely studied "to see if any lessons can be learnt." He added: "It seems, however, that emergency plans we already have coped adequately with this."
Last night, the cost was being measured not in financial losses but in the delays suffered by the thousands of passengers expecting to travel yesterday and the miles of clogged roads surrounding the airport.
In that sense, the devastation was very real. More than 300 flights to Terminal One, which handles domestic, Irish and European flights, had been cancelled or diverted, and thousands of passengers were jammed in Heathrow's three other terminals, 15 miles west of central London.
Dozens of incoming flights were diverted to Stansted, or Southampton. British Airways, the worst affected airline had to cancel around 200 Terminal One flights, and only managed to resume flying yesterday afternoon.
British Midland operated a limited inbound-only service into Stansted airport until yesterday afternoon. SAS, the Scandinavian airline, said 11 flights from Copenhagen, Denmark, were diverted and came back empty, the passengers either trapped at Heathrow or abandoning the trip.
Although the fire did not spread, there were still hour-long delays to departures from Terminals Two, Three and Four, while arrival delays varied.
During the morning, the police closed a vital road access tunnel - for three hours - linking the M4 to the airport and within 15 minutes a five- mile tailback developed.
"It was unfortunate timing for us as the tunnel was closed for at least an hour after 7.30 and this was when the staff were trying to come into work," said a spokesman for BAA.
British Airways said it cancelled three long-haul flights, to Tokyo, Los Angeles and San Francisco, because many passengers failed to show up, apparently caught in traffic jams that built up on the M4 and other roads leading to Heathrow.
When passengers were allowed back into the terminal after its reopening, there was little evidence of damage apart from slight smoke-staining to the ceiling. But fire service investigators said they believed equipment in the ceiling cavity may have been damaged.
Many passengers complained of a lack of help. Anthony Truman, 57, from Putney, south west London, who was trying to fly to Bilbao in Spain, said: "There is nothing coming up on the screens and I just don't know whether I'm queuing in vain. People are being polite but nobody knows anything."
It could have been much worse. Around 70,000 people use Terminal One every day. "It was extremely fortunate that the fire was very early in the day. Two hours later the terminal would have been packed and there could have been a chaotic evacuation," said Professor Ed Galea, director of the fire safety engineering group at the University of Greenwich in south-east London.
It is estimated that the damage will run to hundreds of thousands of pounds. The London Fire Service and British Airports Authority will both conduct inquiries.
Leading article, page 20
Heathrow nearly normal
Passengers travelling on British Airways flights should face little or no difficulty at Heathrow over the weekend, the airline said last night.
BA is the biggest carrier out of Heathrow and runs about 70 per cent of the flights out of Terminal One. The airline is expected to run 240 incoming and outgoing flights today.
The airline has assured passengers that although there may be some "minor delays" in the morning, the service should be back to normal by midday.
Passengers with inquiries are advised to call especially set up national hot-line number 0345 222 111.
The minor delays in the morning, say BA, are due to the fact that around 100 incoming flights were cancelled yesterday. Although the incoming flights resumed at 3pm, the delay would have a "knock-on" effect on the early part of today.
British Midland, the second biggest carrier out of Terminal One, said that it would be running a normal service and even promised "additional services" to cope with the extra demand.
The other airlines operating from Heathrow also hope to have a full schedule of flights over the weekend.
BAA, owners of the airport, advised passengers to check with their airline before setting off for the airport.Reuse content