Chinook's last flight ends in controversy

Crash / `error of judgement'

THE last journey of Chinook helicopter HC2 ZD576, call-sign F4J40, was not a routine flight. Based at RAF Aldergrove not far from Belfast, the Chinook unit there normally carried out duties within Northern Ireland.

This was something special: carrying 25 top intelligence people to Scotland for a high-level conference at Fort George, Inverness, last June. The huge cr-aft never made it, crashing in fog into a remote Scottish hillside.

Even after months of investigation and sifting of evidence, exactly how and why it happened remain not matters of fact but of opinion. Sabotage, major technical failure or electromagnetic interference were ruled out. The two experienced RAF pilots were competent and physically fit; there is no evidence that either were under any emotional stress. Beyond that, almost everything is speculation; and the various explanations for the mystery have divided the RAF.

The Independent on Sunday has obtained a full copy of the unpublished report of the RAF board of inquiry. Its conclusions hardly support the Government's statement last week that the pilots were guilty of negligence - a statement that angered a number of serving and former RAF helicopter pilots. The inquiry concluded that the pilot in charge, Flight-Lieutenant Jonathan Tapper, had probably made an error of judgement, but should not be criticised for human failings. Yet two senior RAF officers, basing their conclusions on the same evidence, pronounced Tapper and his co-pilot, Flight-Lieutenant Richard Cook, guilty of gross negligence.

So how much do we know? The photocopy of the route Tapper lodged with an operations clerk at RAF Aldergrove, near Belfast, before take-off, bears out his reputation as a meticulous pilot. The route is clearly marked: heading over County Antrim, the Irish sea, the Mull of Kintyre, and over the Scottish mainland north to Inverness.

Tapper was an experienced Chinook pilot, on his second detachment in Northern Ireland of the year. He had a total of 3,165 military flying hours while Cook had notched up 2,867. They took off at 5.42pm. Flying at more than 100mph, they crossed the coastline heading for Scotland. The likelihood is that Cook was actually controlling the craft, with Tapper sitting beside him.

At 5.55pm one of the crew, probably Tapper, made a radio call to an army base in Scotland. The call had no emergency or urgency prefix, and was made in a calm tone of voice.

The craft was heading straight for the Mull of Kintyre, which was shrouded in fog. About five minutes later several people on the Mull heard what was described as a dull thump, followed by a loud whooshing and whistling sound. The Chinook, flying at well over 100mph and climbing at 30 degrees, had smashed straight into a hillside, killing everyone on board instantly. That much is clear, but since the craft carried no black box or cockpit voice recorder,much of the rest is deduction, conjecture and interpretation.

The inquiry said the pilots were experienced and respected, but were said to be quiet, relaxed and lacking assertiveness: perhaps, it speculated, there was too much mutual acquiescence. Perhaps Tapper was anxious to complete the mission and return to Northern Ireland; perhaps alti-meter settings were wrong; perhaps, in poor visibility, the pilots suffered from a "goldfish bowl" effect and were disorientated.

Perhaps, it went on, an abnormal temperature reading had occupied the pilots' attention. This type of Chinook, it noted, had experienced a number of unforeseen malfunctions, and something of that sort might have distracted the crew. The inquiry concluded that weather was a contributing factor: Tapper - quite reasonably the board judged - opted to fly by observation rather than instruments.

County Antrim and most of the Irish sea was fairly clear, but the Mull was obscured by fog. According to the board's reconstruction of probable events, the craft approached the Mull at a fast speed in a steady climb, known as a cruise climb.

The pilots would have seen that they were flying into poor visibility and, according to the board, appear to have opted to climb to safety altitude rather than turn away or turn back. This altitude was calculated by adding 1,000ft to the height of the highest peak on the route: the map Tapper left behind illustrates that he correctly calculated it as 2,800ft, but inexplicably the helicopter hit the hillside at 810ft.

The board concluded that the most probable cause of the accident was that the pilots mistakenly felt their steady climb was sufficient to take them over the hills of the Mull.

Other human failings such as disorientation and distraction could have contributed to the accident. But the board concluded it would be incorrect to criticise either Tapper or Cook.

The 42 pages of conclusions were then sent to senior RAF officers. The pilots' commanding officer, Group Captain PA Crawford, registered a sharp dissent, saying he found the hypothesis of a high-speed climb incredible.

He said helicopter crews knew that when nearing high ground in poor weather the alternatives were to slow down and if ne-cessary stop, turn away or turn back, or carry out a safe climb. He declared: "I do not believe even the most junior crew would have selected a cruise climb technique that close to the Mull."

The report then went to Air Vice-Marshall JR Day, who said the pilots were guilty of gross negligence. He said under the rules for flying by observationthey should have slowed down, turned away or turned back. If they planned to switch to instru-ment flight, he said, they should have climbed to above safety altitude well before they approached the Mull.

He said of Tapper: "I cannot categorise his failure as an error of judgment: this would suggest that he made an honest mistake. To the contrary, he did not exer-cise appropriate care and judgement." The report was passed to the air officer commander-in-chief who concurred, commenting: "Lamentably, all the evidence points towards them having ignored one of the most basic tenets of airmanship."

The Government followed the two senior officers rather than the board. But the true causes of the Chinook remain a mystery and will probably always do so.