AAIB investigation to DJI Phantom 4 PRO, (UAS Registration n/a) 150919
Impacted a Sea Stack during filming, Mangestera Stacks, Isle of Lewis, 15 September 2019.
Summary:
The UAS was flown at Mangersta Sea Stacks, Isle of Lewis in order to capture cinematic shots for a television series. The electronic flight log showed that the UAS was travelling at 6.5 mph at the last recorded data point. Whilst the UAS was being flown near to the Sea Stack, it either drifted or was flown too close to the feature before it struck the Sea Stack and then fell into the sea below it.
The UAS pilot stated that the accident happened very quickly. He and the observer did not know exactly what had happened, but the last recorded images showed the sea stack coming into view before the image recording ended, with the UAS flying sideways towards it. The flight log did not show any errors and there was no suggestion of a technical failure. The obstacle avoidance system did not detect the stack, give warning of an imminent impact or automatically avoid the stack. Prior to impact, the UAS had been holding its position adequately in the air in wind speeds of up to 8 m/s (15.5 kt). The UAS was not recovered so the cause could not be determined.
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