Air accident investigators have confirmed for the first time that there are marks on wreckage recovered from downed Rescue 116 consistent with the Coast Guard aircraft striking rocks.

Although the Air Accident Investigation Unit (AAIU) have stated that although the investigation is in its early stages, there are indications that the downed helicopter may have hit rocks.

"At this early stage in the investigation it is not possible to be definitive about the exact nature of damage to the recovered wreckage or indeed the circumstances of the accident," the statement from Chief Inspector of Air Accidents, Mr Jurgen Whyte, in consultation with Investigator-in-Charge, Mr Paul Farrell read.

"However, there appears to be marks on some of the recovered wreckage which are consistent with the tail of the aircraft contacting rocky surfaces on the Western end of Blackrock."

Investigations are now continuing with to ascertain exactly the initial point of impact.

"The AAIU has visited Black Rock Light House, on the approaches to Blacksod bay, which is close to the last recorded position of the helicopter. Some helicopter wreckage has been recovered from the general area of Black Rock Light House," the statement continues.

"This wreckage is primarily from the tail area of the helicopter."

The AAIU has extended its "sincere sympathies" to the families and friends of the crew of Rescue 116.

"The Investigation has been working with the Garda Síochána, Coast Guard, Irish Air Corps, the Irish Marine Institute, and many local persons and agencies with the primary objective of locating and recovering the missing crew members, read the statement.

The AAIU also said it was anxious to recover and examine as much wreckage as possible, and in particular to recover the craft's black box.

"A significant amount of wreckage has been recovered from the sea and this has been logged and will be brought to the AAIU wreckage facility in Gormanston, Co Meath, for detailed examination."

"Equipment aboard surface search vessels has detected a signal which is believed to be from the underwater locator beacon attached to the aircraft’s “Black Box”. This signal points toward an area which will be the focus of further, multi-agency investigation activities at the earliest opportunity, subject to weather."