Air Chief Marshal Sir William Wratten has criticised evidence suggesting that the 1994 Chinook helicopter crash could have been attributed to software failure.
Wratten was the more senior of two air marshals who both overruled the inconclusive findings in a report by an RAF Board of Inquiry into the crash of Chinook ZD576 on the Mull of Kintyre in June 1994.
The accident killed all 29 people onboard, including four crew and 25 senior police and intelligence officers. Wratten ruled that the pilots had been grossly negligent.
He said that comments about the Chinook's software verification procedures were "misinformed". He described the recent TV and press coverage of matters relating to the crash as "highly selective and seriously misleading in nature".
"It is the nature and wilful ignorance of these accusations that drives me now to break the silence we have striven to hold," he said.
The comments came as the former defence secretary Malcolm Rifkind met the current defence minister Geoffrey Hoon to ask for the verdict of gross negligence against the pilots be dropped.
Computer Weekly comment
Sir William Wratten's statement on why he believes the pilots were to blame for the Chinook crash is impressive in its detail. And he may be right.
On the other hand, as the report of the RAF Board of Inquiry said, a technical malfunction that left no physical evidence could have been a factor.
The point is we cannot be certain. The critics of the decision to blame the pilots cannot produce evidence that they were not to blame. But Wratten has not produced any hard evidence that they were. That evidence simply does not exist.
Indeed, whenever software is suspected as a cause of a major fatal accident it may be impossible to prove. No supplier can be expected to state openly that their software was to blame for a major fatal accident. Yet only the supplier will have enough knowledge of their systems to say whether it was to blame or not. This is one of the reasons why the verdict of gross negligence against the pilots is unsafe.