The pilot of a Scottish police helicopter flew for 10 minutes after two low-fuel warnings before both engines on his Eurcopter EC135 flamed out and the aircraft plunged through the roof of a downtown Glasgow, killing the pilot, two others onboard and seven people in the bar. The aircraft’s main fuel tank contained about 160 lb of usable fuel at the time of the crash.
Those were among the findings of the U.K. Air Accidents Investigation Branch investigation into the Nov. 29, 2013 crash. The AAIB published those findings Dec. 10.
The EC135 T2+, owned and operated buy Bond Air Services, was not equipped with flight recorders, not was it required to be. The AAIB based its findings on analysis of data and recordings recovered from non-volatile memory in systems on the helicopter and radar, radio, police equipment and closed-circuit TV recordings. They also tested systems on the accident aircraft and another EC135.
According to the AAIB, the helicopter departed Glasgow City Heliport at 2044 local time with roughly 880 lb of fuel onboard to support Police Scotland operations, with the pilot and two police observers on board. They performed several tasks south of Glasgow City Centre, in Dalkeith (about 40 nm east of Glasgow), and to the east of Glasgow before heading back to the heliport.
About 2.7 nm from the heliport, the right engine flamed out followed about 32 sec later by the left engine’s flameout. The pilot did not achieve an autorotation and flare recovery; the AAIB did not determine why, though it noted the pilot faced “particularly demanding circumstances.” It said the helicopter descended at a high rate, falling through the bar’s roof. In addition to those who died as a result, 11 in the bar were injured seriously.
While investigators recovered about 160 lb of usable fuel from the main tank in the wreckage, they found no fuel in the two-cell supply tank fed from the main tank by two transfer pumps. Each supply tank cell feeds the engine on its respective side. Investigators deduced that both transfer pumps “had been selected off” during the return from Dalkeith and remained off “for a sustained period before the accident.” They remained off despite low fuel indicators and audio warnings that “had been triggered and acknowledged,” the AAIB said, adding the audio warnings “were acknowledged five times.” The flight continued beyond the 10-minute period after a low-fuel warning that is specified the EC135’s emergency procedures.
The AAIB said it could not determine why the fuel pumps were left off. It said it found no signs that the fuel indication system was not functioning properly.