The Ministry of Defence (MoD) is sitting on a report that questions the impartiality of RAF accident investigation procedures, including those that were applied after the notorious crash of a Chinook helicopter on the Mull of Kintyre in June 1994.
The MoD has consistently blamed the pilots for the crash and rejected suggestions that faults with the Chinook’s safety-critical software could have played a part.
But, the Tench report could undermine the MoD’s claim that RAF crash inquiries are reviewed by independent air marshals who have no vested interest in the outcome of the accident investigation.
William Tench was the chief inspector of civil aircraft accidents in 1986 when he was commissioned by the then defence minister Trefgarne to “review the procedures pertaining to Service Boards of Inquiry”.
On the advice of officials, the Tench report has remained unpublished since it was completed in the late 1980s. In March this year, defence minister John Spellar said he had asked his officials to consider publishing it, but this has not yet happened.
Now three senior Fellows of one of the world’s most eminent professional aviation body, the Royal Aeronautical Society, have disclosed one paragraph from the Tench report.
They quote Tench as saying that the “involvement of some Station Commanders, Air Officer Commanding’s Staff Officers and even the Commander in Chief, is an unwelcome intrusion upon what should be the complete independence of the Board of Inquiry”.
After the crash, a three-man RAF Board of Inquiry found that, on the available evidence, it would be incorrect to blame the pilots. The board had heard that there had been a number of unexpected “flight critical” engine surges related to the helicopter's new software-based Full Authority Digital Engine Control (Fadec) system.
A technical malfunction of the Fadec that left no physical trace was one possible factor, the board said.
Despite the board’s speculative findings, two air marshals John Day and William Wratten reviewed this evidence and concluded that the two pilots were negligent to a gross degree. The judgement of the air marshals was endorsed by air chief marshal Michael Graydon, chief of air staff at the time.
Now the three Fellows of the Royal Aeronautical Society have revealed that John Day, as air officer commanding No 1 Group, was involved in controlling the introduction into service of the Chinook Mk2, and reported to William Wratten, who in turn reported to Michael Graydon.
There is no evidence of any impropriety by any of the air marshals.The Royal Aeronautical Society fellows are critical of the procedures that, they believe, may give rise to possible conflict of interest. In the light of this, they say that the “integrity of the reviewing officers' decisions may need to be challenged”.
In their new leaked report, the three members of the Royal Aeronautical Society also said that twice in early 1994, before the crash of a Chinook Mk2 killed four crew and 25 senior intelligence officers, the MoD’s airworthiness assessor at the Defence Evaluation and Research Agency at Boscombe Down had ceased trials flying on the Chinook Mk2 because of unanswered questions over the Fadec system.
Despite Boscombe Down’s halt on trials flying, there was no similar order to halt operational flying.
An MoD spokeswoman said that none of the air marshals were involved in the decision to release the Chinook Mk2 into service, but they may have played a part in decisions relating to the aircraft once it was approved for safe flight.
In a separate development this week, the MoD has refused a request by the families of the pilots who died in the Mull accident to release an official assessment of the Chinook Mk2’s airworthiness which was written by Boscombe Down in 1993, prior to the crash.
It is known that Boscombe Down wanted the Fadec software rewritten before the helicopter went into service, but its official analysis and findings have never been published. Citing exemptions under the Code of Practice on Access to Government Information, the MoD says it is keeping Boscombe’s evaluation secret.
Meanwhile, Malcolm Rifkind, the secretary of state for defence at the time of the crash, has said the verdict against the pilots now appears unsustainable.