An FAI has been told it would not be realistic to expect the same levels of safety from offshore helicopters as jet aircraft.
Willie Rennie repeats calls for FAI reform on anniversary of crash involving John Yuill and Lamara Bell.
The inquiry has already been delayed once and will now be rescheduled due to coronavirus.
Sophie Parkinson's mother said the decision, which is due to the coronavirus outbreak, is 'depressing'.
Four passengers died when a Super Puma crashed near Shetland in 2013.