It has been revealed that military documents, which have only just been recently published, shows that a Chinook helicopter which crashed and killed 29 people, was "positively dangerous."
The accident happened on the Mull of Kintyre due to a computer flaw. Until recently the RAF has blamed the two pilots for the crash.
The collision of the Chinook ZD576 killed the two pilots and 25 senior police and intelligence officers, on 2 June 1994.
The RAF Board of Inquiry was unable to pin point why the incident happened. It did not rule out problems with the Chinook Mk2's innovative, software-controlled 'Fadac' fuel control system as a contributory issue in the accident.
Professional negligence in aviation
However, it has recently been discovered that in internal Ministry of Defence documents, the RAF approved the vehicle, declaring it to be air-worthy, despite knowing the dangerous flaw in the helicopter's fuel system.
The disapproval is contained in a memo written in September 1993 - nine months before the crash on the Mull of Kintyre - by the Superintendent of Engineering Systems at an MoD establishment at Boscombe Down, Salisbury.
IT experts at Boscombe Down were tasked with checking the Chinook's Mk2's Fadec software as part of the examinations to see whether the helicopter was airworthy.
The Superintendent's memo also said that a vulnerability analysis by Boeing, the Chinook's manufacturer, had categorised the Fadec software as "safety-critical" because "any malfunctions or design errors could have catastrophic effects."
The Fadec controlled the flow of fuel to the Chinook's two jet engines - and it could not be overridden by pilots. The Superintendent noted: "The standard of engineering is demonstrably not that to be expected of software intended for the purpose of controlling a safety critical function in an aircraft."
After an assessment of the Fadec software the Superintendent of Engineering Systems said that the density of deficiencies was so high that the software was unintelligible.
He said of the irregularities in both the software code and documentation: "One of these, the reliance on an undocumented and unproved feature of the processor, is considered positively dangerous."
He added that the software: "falls significantly short of the standard required and expected for a safety-critical system No assurance can be given concerning the fidelity of the software and hence the pilot's control of the engine (s) through Fadec cannot be assured."
That letter, written in October, which was addressed to the MoD's Director Helicopters Projects, said that Boscombe Down had been unable to recommend Controller Aircraft Release [CAR].
Without the CAR, the Chinook Mk2 could not be released into operational service. Boscombe Down wanted the rewriting of the Fadec software "with some urgency."
Despite the grave warning, the RAF refused to believe these concerns and agreed for Aircraft Release. The Chinook went into operational service in early 1994, without a rewriting of the software or corrections to anomalies in the code. Such fears proved to be justified, because the crash happened just months later.
Whilst the families of the deceased fight for justice, claiming the Chinook was rushed into service and safety issues were ignored, the Ministry of Defence declines to accept public liability and states the documents are not new evidence and still believes the pilots were professionally negligent.
This article looks at the Chinook disaster and questions who made the deadly mistake and who was responsible for the Professional negligence.
