The Ministry of Defence has altered its stance on the fatal Chinook helicopter crash on the Mull of Kintyre in 1994, and now admits to uncertainty over the precise events leading up to accident.
The move comes as Lord Chalfont, chairman of the Mull of Kintyre Campaign Group, tries for the second time to secure a meeting with the prime minister for senior peers and MPs who want Tony Blair to open a new inquiry into the RAF's verdict of gross negligence against the two pilots of Chinook ZD576. Lord Chalfont's first request for a meeting with Blair was rebuffed.
In its latest statement on the crash, the ministry did not appear to rule out an emergency in the last moments of flight. According to safety-critical software specialists, one possible cause of this could have been an unexpected acceleration of one of the two jet engines brought about by a problem with the Chinook's Full Authority Digital Engine Control (Fadec) system.
In past statements to Parliament the MoD has suggested there was no doubt over the flight path and behaviour of the Chinook in the moments before the accident. Although now admitting to some uncertainty in these details, the MoD continues to insist that there is no doubt whatsoever that the pilots were grossly negligent.
"It is possible to be certain of the cause for something happening even though the precise details of the events leading up to it are less definite," explained the MoD.
Les Hatton, professor of software reliability at Kent University, who has made enquiries into the Chinook accident, said, "If a rotor fails there is clear evidence of failure for investigators. With software, there is frequently no clear evidence of failure - it is all too easy to blame the pilots in this case."
The crash of Chinook ZD576 in June 1994 killed four crew and 25 senior intelligence and police personnel.