LONDON — A police helicopter that plummeted into a Scottish pub in November, killing 10 people, suffered failure of both its engines from an as-yet-undetermined cause, investigators of the accident said Friday.
The chopper still had plenty of fuel when its engines suddenly cut out in the skies above Glasgow on the night of Nov. 29, 2013. The stricken helicopter then plunged hundreds of feet, crashing through the roof of the Clutha Vaults pub on the banks of the River Clyde.
The tavern was packed with dozens of revelers enjoying a live concert on the eve of St. Andrew's Day, Scotland's national day. With part of the helicopter still protruding above the rooftop and dust choking the air, coughing and bleeding pub-goers struggled to find their way out.
All three people aboard the Eurocopter EC135 T2 — two police officers and the civilian pilot — were killed, as were seven people in the bar. More than 30 others were injured.
A preliminary report issued Friday by Britain's Air Accidents Investigation Branch said that the helicopter had been in the air for a little over an hour and a half when the pilot made a standard request for permission to return to Glasgow City Heliport, which was granted. But a few minutes later, the right engine of the chopper "flamed out," followed shortly by the left engine.
Without power, the helicopter plummeted toward the ground at high speed; witnesses reported that it dropped from the air in an eerie silence. By the time it hit the Clutha's roof, the chopper's blades and tail rotor had already stopped rotating.
What caused the sudden double engine failure is still unknown. Attention has focused on possible problems with the aircraft's fuel-supply system. Investigators have not ruled that out, though they said about 167 pounds of fuel was still in the chopper's various tanks.
Investigators are also trying to determine why the pilot did not issue an emergency signal when trouble became apparent.