The Amsterdam Disaster: Mystery of the flight to disaster: Christian Wolmar, Transport Correspondent, charts the course of the El Al jet, and the possible causes of the crash

THE fateful 14-minute journey of the El Al cargo Boeing 747-200F started on runway 01L at Amsterdam's Schiphol airport as the plane took off towards the north at 6.22 on Sunday night.

Although there was a relatively strong cross-wind from the east, it was not powerful enough to prevent the use of the runway as it is the preferred one for take-offs, even though taking off into the wind is the easiest for pilots.

The pilot, Isaac Fuchs, would have taken the aircraft, fully laden, straight up for a couple of miles and then, according to the rule book, he would have eased off the climb so as to execute a sharp 180-degree turn to the right to bring him on to the course of the Nyker beacon, which would have put him en route for Tel Aviv.

The authorities at Schiphol are very noise conscious and the turn is required to be made very accurately because there are residential areas just off the flight path.

The plane was fully laden with 114 tons of cargo including perfume, textiles, electronic equipment and machinery. It had filled up completely with 180,000 litres (39,600 gallons) of aviation fuel, which is cheaper in Amsterdam than anywhere else in Europe.

Shortly after executing the turn, fire broke out in the number three, nearside right engine and the pilot reported this to the control tower.

When fire is reported in an engine, standard procedure is to shut it down and isolate it as fast as possible. This can be done very quickly, especially as Boeing 747s have three, rather than two, crew. The third member, the flight engineer, is a vital help in this procedure. First the throttle is closed, then the fuel supply is cut off. The fire handle is pulled to cut off the hydraulics and the electrics and, as an extra precaution, this effects a second cut-off of the fuel. Then, by twisting the fire handle, foam is sprayed into the engine. The crew will wait for half a minute to see whether the fire is extinguished and then, by twisting the handle the other way, pump a further bottle of foam on to the engine.

Clearly this procedure failed, because the pilot then reported, when he was at a height of about 5,000ft, that the other right-hand engine, number four, was also on fire. It is very likely that this was caused by debris from number three engine, which is set further forward than its neighbour; aviation experts say the chances of two engines completely failing independently of each other is infinitesimal.

Both engines then broke off from the aircraft and fell into the Ijsselmeer, which is about nine miles from where the aricraft eventually crashed.

Without its right-hand engines, the jet could not turn left, and the pilot circled, in an attempt to line up with the east-west runway 27. The control tower had wanted him to align with runway 06 which runs north-east, because of the wind, but the pilot apparently felt the easterly tailwind would help him reach the runway. In these emergency situations, the pilot has the final say.

The aircraft would have been unable to land without jettisoning some of its fuel, which it tried to do by opening special vents, as it was above its maximum landing weight. If it had to tried to land with the full load and the fuel, the tyres would have burst and the undercarriage may not have been able to sustain the strain.

'These cargo planes are always full as they fill them to the gunwales to maximise income,' said one pilot who has experience of flying cargo planes. 'The take-off weights are critical but you never quite know how much you have on board as they estimate the weight, rather than weighing each item of cargo, which is impossible.'

In the event, the aircraft never got anywhere near the runway because the turning manoeuvres made it lose too much height. At this stage, too, although it is technically possible to land without two engines, it had lost half its electrical power and its hydraulics, and it is likely that it was critically disabled and the pilot was no longer in control. The 747 smashed into the apartment blocks at around 6.36pm.

William Tench, a former head of the Department of Transport's Air Accident Investigation Branch, said the investigation would centre on why the engine broke up so comprehensively and so quickly: 'It is very unlikely to have been a design fault, because 747s have been in such wide use, although they do keep on updating these engines to ensure they run with higher compression and more efficiently.

'The first engine's failure is important, but that's not the only thing that caused the crash. Losing one engine would probably not have been a serious matter. The investigators will have to work out why the fire could not be put out and why the second engine was affected.'

An engine can fail for a number of reasons, such as failure of the combustion chamber or a faulty blade which then flies off into the engine. If several blades next to each other are broken, the fan will start to spin in an unstable way, causing serious stress. This is probably why the engines fell off. The Boeing's engines are designed to come off in such a way that they do not smash into the wing. This is to ensure that if an aircraft has to land without an undercarriage, the engines do not cause catastrophic damage to the rest of the plane.

Mr Tench said that sabotage could not be ruled out. Substances could be placed in the engine or the solvents could be diluted to wear away. But the Israeli authorities have been surprisingly quick to deny suggestions of sabotage.

The age and history of the aircraft was unremarkable and unlikely to have been a contributory cause. The 747-200F aircraft was manufactured at Boeing's Seattle plant and delivered to El Al in March 1979. It was the 362nd Boeing 747 made, had completed almost 10,000 flights and flown nearly 45,000 hours - normal figures for an aircraft that age.

A bird strike is another possibility, although the investigators have said this is unlikely. Last week, pilots with a local airline reported a couple of hits from birds. Dusk is a time when birds are often beginning to mass for migration, and there are large colonies of redwings in the area set to fly south. However, a spokesman at Schiphol airport said that bird- scarers are employed on a 24-hour shift basis, and there were no reports of unusual bird movements on Sunday night.

The investigation team, which will be led by the Dutch, will include members from Boeing and from the makers of the engines, Pratt and Whitney.

(Photograph omitted)