Both pilots and 12 remaining passengers escaped and now nine of the survivors have won compensation understood to be between £2.5 million and £3 million.

Lisa Gregory, head solicitor at the Aberdeen office of law firm Digby Brown, which represented the claimants, said: "Our clients were a group of people who were just going to work when their lives were changed in some of the worst ways imaginable.

"The cases were about providing them with access to legal recourse and fair compensation. All of those involved in the incident will have to live with its effects and repercussions for the rest of their lives. The most important outcome is that the settlements will hopefully allow those affected by the events of that night and their families to move on with dignity.''

Investigators found pilots failed to properly monitor the flight instruments on approaching Sumburgh Airport on Shetland.

A final report by the Air Accidents Investigation Branch (AAIB) issued in March found no mechanical fault with the helicopter, which was returning from the Borgsten Dolphin support vessel to Sumburgh.

The investigators made several recommendations, including a requirement for pilots who are licensed to fly through bad weather to receive regular training on how to read the flight instruments which are specific to the type of helicopter being operated.

They called for helicopters, which already must have cockpit voice recorders, to be fitted with devices to capture images.

The AAIB also recommended that large helicopters certified for offshore operation should only have cabin seating layouts, which would mean that in an emergency each exit would need to be used by no more than two passengers.