The accident investigators made a number of recommendations, including that Clydeport appoint someone as "designated person" under the Port Marine Safety Code.

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The Esa said it was not interested in the features drone owners designated as their virtual docking port - it wanted to gather data only about the way humans navigated the robot craft.

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Local fishermen are restricted from sailing beyond the designated area's perimeter, several dozen miles outside the main port.

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Major shortcomings in the port's safety management system were also overlooked because there was no "designated person" in charge, the report found.

BBC: Firms charged over River Clyde Flying Phantom tug deaths