The Lord Advocate defended the timescale for a fatal accident inquiry into the Super Puma crash which left 16 people dead in 2009.
Frank Mulholland spoke out following a campaign by the Unite union to reform the current system.
Earlier this year it was announced the inquiry will finally be held in Aberdeen, starting on January 6 next year.
Mr Mulholland said the five-year wait was due to a complex web of technical investigations – bound by national and international regulations – which had to be carried out at home and abroad.
Like all air accidents, the main investigation into the crash off Peterhead on April 1, 2009 was under taken by the Air Accident Investigation Branch.
Two-and-a-half years after the incident, it published its final report.
Mr Mulholland said that under statute, the AAIB was prevented from apportioning blame. Only once it has finished its technical investigation can the Crown Office, police and Health and Safety Executive examine whether there has been recklessness or gross negligence involved.
As the prosecuting authorities have no power to direct the AAIB, they must use their own expert witnesses to help gather extra evidence and make sure it is of the standard needed for a possible trial.
Mr Mulholland said within a year of the final AAIB report the Crown had completed its own investigation and announced there would be no criminal proceedings.
“The process takes some time as you are dealing with a very complex and technical investigation,” he said.
The Lord Advocate said that he and his staff were “quite upset” by implications that “critical safety information” was not being placed in the public domain.
“Nothing could be further from the truth,” he said.
“At the time you had two interim reports from the AAIB dealing with safety, a special bulletin and of course the final report on November 20, 2012.
“All that information was out there and published as soon as it could be by the AAIB.”