The families of 16 men who died in a North Sea helicopter crash have called for the aircraft's operator to be prosecuted after an inquiry found the tragedy might have been avoided.
Fourteen oil workers and two crew died when the Bond Super Puma plunged into the water off the Aberdeenshire coast on April 1 2009.
Their relatives have called for the Crown Office to review its decision not to pursue a criminal prosecution against Bond after a fatal accident inquiry (FAI) identified failings in the maintenance of the aircraft's gearbox in the days before the crash.
Sheriff Principal Derek Pyle said the tragedy was "possibly" the result of a failure to detect a significant fault in the helicopter's gearbox.
Audrey Wood, who lost her son Stuart Wood in the crash, said: "We, the families, feel let down by the system. We just wanted answers. We will never have closure, this will go on and on for us.
"We are asking to meet with the Lord Advocate to try and convince him that the case against Bond helicopters needs to be looked at again.
"No more families should have to go through what we have been through."
Lorraine Doyle, from Cumbernauld, Lanarkshire, who lost her father Raymond in the crash, said: "Basically this could have been avoided. We've always known it but now it's in black and white.
"How Bond thinks we could get closure from this, I don't know. It's almost cruel what we've had to go through. You can't move on, you go through day to day existing, it's always at the back of your mind. To put us through it for this length of time is cruel.
"And to get the outcome we did, it's not fair."
Solicitor advocate Tom Marshall, who represented relatives at the FAI, said: "There were numerous opportunities for Bond to have prevented this awful tragedy. Had they followed the correct procedure for these craft then the fault in the gear box would have been properly dealt with.
"It's an appalling state of affairs where 16 men can lose their lives while simply returning from work and yet no one has yet been prosecuted."
The families have joined trade unions in calling for a full public inquiry into offshore safety in the North Sea.
The Crown Office said it would meet with relatives but that the decision not to prosecute was "correct".
A statement said: "For a criminal prosecution to have taken place, the Crown would have to prove its case beyond reasonable doubt. The Sheriff Principal makes clear that a reasonable doubt remained over the technical cause of the crash.
"The evidence presented during the FAI has not altered the insufficiency of evidence therefore the decision not to hold criminal proceedings remains the correct one."
An earlier Air Accidents Investigation Branch (AAIB) probe into the crash found that the aircraft suffered a ''catastrophic failure'' of its main rotor gearbox.
Sheriff Pyle, who heard the six-week FAI at Aberdeen's Town House earlier this year, found that Bond had failed to follow the aircraft maintenance manual on March 25 2009 after a metal particle was discovered on the helicopter's epicyclic chip detector.
Bond failed to ensure that communications with the manufacturer Eurocopter were done according to procedure, with the result that "misunderstandings arose between the parties" and contributed to the failure to carry out the maintenance.
The sheriff said that while it was "certainly possible" that the gearbox would have been removed if Bond had carried out the maintenance, that had not been proved "on the balance of probabilities".
He said: "The essential fact is that everyone in the company well knew that maintenance must be done by the book.
"On one occasion, that fundamental rule was broken. It resulted in the failure to detect a significant fault in the helicopter's gearbox, which possibly - but only possibly - resulted in the crash."
In a statement B ond Offshore said: "W e have always accepted that we made mistakes through honest confusion over telephone calls and emails.
"Lessons needed to be learned, lessons have been learned and lessons continue to be learned. We are absolutely committed to continuing to drive safety improvements across the business, and will study the Sheriff Principal's recommendations carefully, along with our industry colleagues."
The inquiry heard a witness account of how the helicopter fell from the sky ''like a torpedo'' followed separately by its detached rotor blades.
The crash claimed the lives of captain and co-pilot Paul Burnham, 31, from Methlick in Aberdeenshire, and Richard Menzies, 24, from Droitwich Spa in Worcestershire.
Five men from Aberdeen died: Alex Dallas, 62, James Costello, 24, Stuart Wood, 27, Vernon Elrick, 41, and Brian Barkley, 30; and two workers were from Aberdeenshire: Leslie Taylor, 41, from Kintore, and Warren Mitchell, 38, from Oldmeldrum.
The other victims were Raymond Doyle, 57, from Cumbernauld; David Rae, 63, from Dumfries; Gareth Hughes, 53, from Angus; Nairn Ferrier, 40, from Dundee; James Edwards, 33, from Liverpool; Nolan Goble, 34, from Norwich; and Mihails Zuravskis, 39, from Latvia.
Many of those killed worked for KCA Deutag Drilling and were returning from BP's Miller platform at the time of the crash.
Manufacturer Airbus Helicopters, previously known as Eurocopter, said it will analyse the recommendations of the FAI.
A spokesman said: "This accident and resulting loss of life was a tragic event that deeply saddened everyone at Airbus Helicopters. We would like to express again our deepest sympathies to the families, friends and colleagues of those who lost their lives.
"Airbus Helicopters takes note of the FAI's three recommendations issued today that involve rotorcraft manufacturers. They will be analysed in depth with other concerned parties, including regulatory authorities, as part of the company's continuous drive toward safety improvement.
"These recommendations are in line with the company's research programmes related to materials, surface treatments, manufacturing processes, and monitoring devices.
"The company took immediate action following the accident to understand the contributing factors and to enhance the safety of the fleet. Airbus Helicopters are confident that the actions implemented to date remove any risk of such a dramatic event recurring.
"The safety of our fleet is our number one priority. We are committed to doing everything possible to ensure the safe operation of our aircraft for the thousands of operators and passengers who rely everyday on our helicopters around the world."
A Scottish Government spokeswoman said: "Our sympathies are with all of those who lost loved ones, friends and colleagues in this tragedy. We welcome Sheriff Principal Pyle's findings following the Fatal Accident Inquiry, and we will now take time to consider those findings in detail.
"This Government has already committed to bringing forward a Bill to implement the recommendations of Lord Cullen's review of FAI legislation within the lifetime of this Parliament."