AAIB investigation to Falcon 8 Trinity Asctec (UAS, registration n/a)

Lost data link, North Sea, 17 April 2017.


The Unmanned Air System (UAS) was operating from a ship in the North Sea to carry out inspection work. After takeoff, when the Unmanned Air Vehicle (UAV) was approximately 20 m away from the ship and at a height of approximately 20 m, the pilot successfully carried out hover checks, in accordance with the operator’s standard operating procedures. He then switched the UAS into GPS mode and the UAV held position, indicating to the pilot the system was functioning correctly. He started flying the UAV onto task, but when it was about 30 m from the ship, the UAV appeared to enter its emergency ‘Come Home High’ mode, indicating a loss of link. The pilot attempted to regain control by switching first to height mode and then to manual mode, but the UAV remained uncontrollable and descended into the sea.

The UAV floated for a few seconds before sinking, although the operator was able to recover it back to the ship.

The UAS was returned to the manufacturer to try to establish the cause of the lost link. Tests on the software, UAV and ground station were unable to identify any faults.

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Falcon 8 Trinity Asctec, (UAS), BAS-02 10-17

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Glossary of abbreviations

Published 12 October 2017