It had attended several incidents during day and was returning to its base on
the edge of the River Clyde, flying at a speed of around 120mph, when the
The AAIB said both engines “flamed out”, meaning they stopped because of a
lack of fuel, despite the fact that there was still 168lb (78kg) of fuel on
board, which was enough to get the aircraft to its destination.
No sign was found of any blockage in the system, but there were a number of
low fuel warnings during the flight.
Investigators said the continuing inquiry would want to find out “why no
emergency radio transmission was received from the pilot, and why, following
the double engine failure, an autorotative descent and flare recovery was
An autorotative descent is employed when an engine fails and the rotors are
powered solely by the upward flow of air as the aircraft descends.
An eyewitness said the Police Scotland aircraft, which was operated by Bond
Aviation, fell from the sky “like a stone”, and an earlier report
confirmed that its rotors were not turning at the time.
The pilot Dave Traill, 51, who had 26 years experience and had flown
helicopters for the RAF in both Gulf Wars, died in the accident with two
police constables who had been commended for their bravery, Pc Tony Collins,
43, and 36-year-old Pc Kirsty Nelis.
An earlier report in December said there was “no evidence” of major
engine or gearbox failure. Shortly after that report Bond temporarily
grounded the same model of helicopter because of a fuel gauge problem.
The AAIB said Capt Traill requested clearance from air traffic control to
re-enter the Glasgow control zone to return to the heliport at 10.18pm. This
was approved and no further radio transmissions were received.
There was no evidence that fuel had leaked from the aircraft either before or
during the impact with the pub, and no blockages were found that would have
interrupted the fuel flow.
John Fyall, for Bond Air Services, said: “While the investigation
continues, we would urge against speculation. We owe it to the memories of
those who died, those who were injured, and the families affected by this
tragedy to help the investigation team answer as many questions as possible
and discover exactly what happened.” The airline pilots’ group Balpa added: “Pilots
want every flight to be safe through full and proper investigation of
incidents and accidents like this one.
“We now know that the engines were not running at the time of the crash
and it appears this was to do with the fuel system. However, pilots, like
the AAIB, will not be satisfied until this is explored further and the exact
reason for that failure is identified.”
There have been repeated calls for a public inquiry into the safety of all
commercial helicopter flights in the UK in the wake of the incident, and
following several helicopter accidents in the North Sea over the past five