When a police helicopter plunged into the Clutha pub in Glasgow city center two years ago, killing ten, an accident investigation was launched to find out what happened and why – a process that is essential to preventing future accidents and loss of life. But smaller aircraft are not required to carry flight data recorders – the black box so vital to air crash investigations. So while the recently published report into the crash revealed some of the reasons behind, there were details – potentially vital details – that couldn’t be known because they weren’t recorded. It’s about time this changed.
The Air Accident Investigation Branch (AAIB) report recorded that the Strathclyde Police Eurocopter EC 135T2+ (G-SPAO) with a crew of three took off from Glasgow Heliport at 8:44pm in order to conduct missions between Glasgow and Edinburgh. The captain was an experienced pilot aged 51, who had flown RAF helicopters in Afghanistan, Iraq, Bosnia and Northern Ireland before retiring from military service and flying helicopters for the police.
At about 10:06pm the helicopter arrived over Bothwell in Glasgow with about 122kg of fuel remaining. Local rules require that a fuel “urgency” (the level below an “emergency” or “Mayday” call) be declared if levels fall below 100kg, and landing should be quick. Because the fuel pump switches that transfer fuel from a reserve to the main fuel tanks were turned off, a fuel warning went off in the cockpit – a warning the pilot cancelled five times.
At about 10:22pm there was 73kg of fuel left in the reserve tank, the helicopter’s two engines failed 45 seconds apart and the pilot was forced to attempt an emergency landing. This was handled poorly for reasons including the helicopter’s low altitude, the darkness of the night, and the failure of the radio-altimeter, a device that in this model of helicopter relied upon engine power to tell the crew the exact distance between the helicopter and the ground below. The helicopter crashed at high speed into the roof of the Clutha Bar, killing the crew and seven others in the pub.
The AAIB established the technical facts of the accident by examining memory chips from various aircraft electronics that survived. This took a very long time, and some uncertainties remain.
Why would a hugely experienced professional helicopter pilot leave the fuel transfer pumps turned off, cancel five low fuel warnings and continue to fly his helicopter below safety minimum fuel levels? Did his experienced police observers challenge him about the warnings he kept cancelling? Critically, we know nothing about what was happening in the cockpit: when and why the pilot cancelled the audible warnings, what was discussed, and whether any action was taken. We don’t know the answers to these questions, nor can we ever know.
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