Letter: Chinook accident

What caused the Chinook disaster (your report, 15 July)? In my opinion, it is undeniable from the evidence that seriously defective flight and engine control software could have flown the helicopter into the ground.

Acceptance test flying of the Chinook HC-2 at Boscombe Down was stopped for four months because of fatally dangerous uncommanded engine and flight control by the aircraft's software. When? The day before the crash.

Three days before the crash, pilot Flt Lt Tapper said he felt unprepared to fly the Chinook HC-2: time had passed since his brief HC-1 to HC-2 conversion training; his capacity to react unhesitatingly was compromised. He was ordered to fly it although in a Chinook Squadron at RAF Gtersloh, 40 hours flying on the HC-2 was mandatory before pilots were authorised to fly it operationally. Chinook ZD576 was the first HC-2 to reach Belfast - two days before the crash; its introduction was chaotic; instructions for aircrew to deal with malfunctions were flawed; the flight manual was inadequate; pilots had grossly insufficient time to get these details instantly ready to mind before flying; potential disorientation, distraction and delay in dealing with sudden problems in flight were inevitable.

Standard civil accident investigation logs the hours pilots flew in the previous 90 and 28 days, but this is missing from the evidence of all six inquiries. How tired were the two pilots? They had already flown nearly six stressful operational hours that day over the "bandit country" of Ulster. Was it all a simple but shamefully unjust equation: "accident plus no evidence of technical malfunction equals pilot error?"

MAJOR (Retd) MICHAEL HAMILTON

Stodrig Farm Cottages

Kelso, Scottish Borders