TRAGEDY WHICH CAN NEVER BE FULLY EXPLAINED

THE police helicopter crew were carrying out their routine duty doing what helicopter crews do best: watching and recording things happening about 2,000ft below. It was a moonless night but cloudless and clear. The lights of Glasgow and Edinburgh were simultaneously visible, the dark ribbon of the Clyde providing a visual navigation cue.

The pilot, David Traill, sat at the right side of the cockpit, the big windscreen providing a panorama of the outside world, the glowing flight and engine instruments on the panel beneath it.

Suddenly, at around six minutes past ten, the silence was broken by the first fuel warning.

Mr Traill would have seen a dashboard light go on, clearly spelling out the words ‘low fuel’.

At that time, all three on board – Mr Traill and his colleagues PC Tony Collins and PC Kirsty Nelis – would have heard a chime over their headphones, alerting them to the warnings.

These were ‘acknowledged’ by the pilot who turned off the alarms, but they kept sounding because the fuel pumps had not been activated. Indeed, the helicopter carried out three jobs after that first alarm sounded.

The central question, which the AAIB report has not been able to answer, is why a veteran such as Mr Traill failed to land immediately, as strict protocols dictate.

The accident hinged entirely on an event for which the report has no explanation: at some point about an hour into the 97-minute flight, two fuel pumps were switched off.

These provide fuel from the main tank to two smaller tanks that feed the two engines directly. So unless the fuel pumps were switched on again, the engines would stop when the fuel in the small tanks ran out, even if there was still fuel in the main tank.

The alternative course of action, according to the drill, was for the pilot to land within ten minutes of a low fuel warning. But following the warning, the pilot neither switched the pumps on nor set course to land quickly.

It is this lack of action which has puzzled the investigators.

The horror of those on board as they realised something had gone catastrophically wrong is barely imaginable.

YET, even when the engines stopped, the aircraft could still have landed safely. Helicopters can glide without power, but to enter a successful ‘autorotation’, as the emergency manoeuvre is known, the pilot must react quickly.

The joystick control must instantly be pushed forward to lower the nose and begin the descent, keeping the speed up, and the lever controlling the rotor blade angle must be lowered so that the air, as the descent begins, continues to keep the rotors turning fast.

Unfortunately, the pilot pulled the lever upward, slowing it rapidly to a stop. The aircraft dropped like a stone.

Sadly, the reasons for this will probably never be fully known.