Treacherous conditions blamed for jumbo crash

Korean Air disaster: Pilot of Boeing 747 may have flown too low during tropical storm without warning from air traffic control

Speculation last night on the cause of the Korean Air jumbo jet centred on the treacherous conditions the pilot had to cope with as the plane descended to land.

Flight 801 from Seoul, South Korea, to Guam was cleared to land when contact was lost as the jetliner was three miles from Agana International Airport.

The Boeing 747 crashed into the side of a hill in dense jungle amid a tropical shower in the early hours of the morning. Air safety sources said visibility at the time was limited to about one mile (1.6 km) due to the heavy rain. Korea Broadcasting System (KBS), quoting air controllers in Guam, said the captain of the jumbo jet said the words "something wrong" shortly before he lost contact with them.

An immediate investigation into the cause of the crash was launched as it was revealed that a landing system, known as a glide slope, which leads planes into the runway, has not been in service at the airport since last month.

The National Transportation Safety Board sent a 12-member team to investigate headed by Greg Feith, who led the investigation of the ValuJet crash last year in the Everglades that was blamed on a fire on board the aircraft. Boeing flight safety engineers were also preparing to fly to Guam to assist the investigation, Boeing spokesman Doug Webb said.

Mr Webb said that the jet involved was a Boeing 747-300 delivered to Korean Air Lines in December 1984. The jet had accumulated just under 50,000 hours of flight time in 8,433 flights or "cycles".

Boeing is still reeling from the loss a little more than a year ago of a Boeing 747-100 operated by TWA. Flight 800 exploded shortly after take-off from New York's Kennedy International Airport - that plane was one of the oldest 747s in service, having been delivered in 1971. Following the crash, Boeing asked British Airways and Virgin Atlantic, as well as other carriers around the world, to carry out inspections on their central fuel tanks on all Boeing 747s.

Four years ago, Boeing decided to fit a new type of engine fuse pin to all its 747s, numbering around 900 at the time, after two disasters in which engines fell from aircraft. The decision to replace the pin came after an crash in Amsterdam which killed 50 passengers, and another in Taiwan in which five people died. Yesterday's loss is the 18th accident involving a 747 that resulted in a total "hull loss."

Max Kingsley-Jones, commercial aviation editor of Flight International, told Sky News that many recent accidents had involved "controlled flight into terrain". He said: "These usually occur in the late stages of an approach, when the crew are very busy operating the aircraft," he said. "Controlled flight into terrain" is the term used to describe crashes that happen when a perfectly serviceable aircraft hits the ground because its crew were unaware that they were flying too low.

The last major crash involving a descent into mountainous terrain saw a Boeing 757 plough into the side of a peak in Colombia in December 1995. That accident claimed more than 160 lives. The flight recorder then showed that alarms went off in the plane moments before it crashed into San Jose mountain on 20 December, four minutes before it was scheduled to land.

Yesterday's crash was a similar distance from the runaway - but was on course, unlike the 757 which had strayed from its allotted flight path. Little is known of the final seconds before last night's crash.

Tragedy in the skies:

The world's worst

aviation losses

582 - 27 March, 1977

Two Boeing 747 airliners belonging to KLM and Pan-Am and carrying a total of 644 people collide on the runway at Tenerife in the Canary Islands and burst into flames.

520 - 12 August, 1985

A Japan Air Lines Boeing 747 crashes into Mount Osutaka on a domestic flight, killing all but four of the 524 aboard.

350 - 8 January, 1996

At least 350 people die when a Russian-built Antonov-32 cargo plane crashes into a crowded market in the centre of the Zairean capital, Kinshasa.

349 - 13 November, 1996

A Saudi Arabian Boeing 747 jumbo jet and Kazakhstani cargo plane collide mid-air near New Delhi, India. This is the world's worst mid-air accident.

346 - 3 March, 1974

A Turkish Airlines DC-10 crashes into a forest shortly after take-off from Paris's Orly Airport.

329 - 23 June, 1985

An Air India Boeing 747 plunges into the sea off the Irish coast, apparently after an explosion.

301 - 19 August, 1980

A Saudi Arabian Airlines L-1011 Lockheed TriStar jet lands on fire at Riyadh airport.

290 - 3 July, 1988

An Iran Air A-300 Airbus is shot down over the Gulf by the US warship Vincennes.

273 - 25 May, 1979

An American Airlines DC-10 crashes after take off from Chicago's O'Hare International Airport. All 271 aboard and two men on the ground are killed.

270 - 21 December, 1988

A Pan Am Boeing 747 is brought down by a terrorist bomb, crashing on the town of Lockerbie in Scotland and killing all 259 people on board and 11 people on the ground.