A Super Puma helicopter ditched in the North Sea in February
Workers who survived a North Sea helicopter ditching did not know they needed to extend aerials on personal locator beacons, a report has revealed.
The devices were blamed for hampering efforts to reach all 18 survivors after their Super Puma ditched in February.
The Air Accidents Investigation Branch (AAIB) bulletin said it took 27 minutes before search craft picked up signals.
The report said that was because the beacons had interfered with one another and shut down.
The report found that efforts to transmit voice messages from the beacons were fruitless because survivors had not extended antennae.
It urged the European Aviation Safety Agency to force manufacturers to add instructions onto the beacons and said more training on the importance of extending the antennae should be given to people in the oil industry.
The beacons were later banned by the Civil Aviation Authority (CAA) although the industry has been pressing to have them reintroduced once technical issues have been resolved.