Offshore union the RMT used the first day of the inquiry to repeat its call for a full public inquiry into helicopter safety.
General Secretary Bob Crow said: "The FAI process has been proven to be far too slow and since the 2009 disaster that is under investigation today there have been three further incidents, one of them fatal, and the families and colleagues of all those whose lives have been impacted by the helicopter safety issue have waited far too long for justice.
"Unfortunately, the FAI cannot deliver that justice and once again we call on the First Minister, Alex Salmond, to throw his weight behind the RMT campaign for a full public inquiry into the whole subject of helicopter safety and the broader issue of working conditions in the offshore industry."
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The call is supported by an aviation law team which has represented victims and families in some of the recent crashes.
Jim Morris, a former RAF pilot and partner in the Irwin Mitchell team, said: "Too many innocent people have lost their lives or suffered life-changing injuries as a result of the helicopter crashes since 2009 and through our work on behalf of victims, we have seen how desperate they are for reassurances that no one else will suffer in the same way."