Fianna Fáil has said it is concerned at the conduct of an Air Corps inquiry into a fatal accident four years ago in which a flight instructor and a trainee lost their lives.
Captain Derek Furniss and Cadet David Jevens died when they flew into a mountain in Connemara, Co Galway, while on a training flight.
Following the incident a number of investigations took place; a coroner's inquest, an investigation by the Air Accident Investigation Unit and a Military Court of Inquiry.
Fianna Fáil Defence Spokesman Sean O Fearghaíl has said that he and party leader Micheál Martin had met the Jevens family and were concerned that proper procedures were not followed in the military inquiry.
Mr O Fearghaíl said that vital evidence from the inquest was overlooked, the findings of the AAIU was used selectively and key personnel were not interviewed in the inquiry, which they claim was legally and technically flawed.
Fianna Fáil has called on Defence Minister Alan Shatter to address the legitimate concerns of the Jevens family.
Meanwhile, a Department of Defence spokesperson has said that it is corresponding with the Jevens family.
The spokesperson said that it had received written correspondence from the family and was responding.
The department said it will not be making any further comment at this time.