Worsening weather delays crashed R116 search until Monday
Search teams believe they have found the fuselage of the downed Rescue 116 Coast Guard helicopter off Blackrock Island.
They have detected a signal from the aircraft's black box in 40 metres of water about 60 metres off Blackrock lighthouse.
Naval Service and salvage experts are "very hopeful" that the bodies of the three missing crewmen will be found in or close to the wreckage.
Deteriorating weather conditions are continuing to delay full sonar scans to pinpoint the exact location of the black box.
Derek Geoghegan, of the Irish Coast Guard, said a small weather window of three hours during which it is anticipated conditions will improve has been identified on Monday afternoon.
It was previously hoped that a full scan and subsequent dive could be carried out today and tomorrow.
Surface searches are continuing off the west coast, but they have been scaled down due to bad weather.
Sources said the lighthouse beacon was fully functioning throughout Monday night and Tuesday morning when the helicopter crashed into the sea.
Captain Dara Fitzpatrick (45) was recovered from the water on Tuesday morning but was pronounced dead on arrival at hospital.
Her funeral takes place this morning in Glencullen, Dublin.
Her three crewmen - Ciaran Smith, Mark Duffy and Paul Ormsby - are still missing.
Rescuers believe they were unable to escape from the helicopter.
The US-built Sikorsky S-92A crashed without any mayday signals being sent or any indication from the flight crew that they were experiencing difficulties.
Air Accident Investigation Unit (AAIU) officials have steadfastly refused to speculate on what might have caused the tragedy.
However, there is nothing to suggest some kind of collision close to Blackrock.
Rescuers are trying to establish why alert devices on board the helicopter were not triggered after the crash.
Debris from the ill-fated aircraft has been found on Blackrock Island and as far south as Achill and Annagh Islands.
All wreckage is being gathered by AAIU officials and will be painstakingly reassembled in a bid to determine what happened to R116.
The Commissioners of Irish Lights (CIL) vessel Granuaile is expected to play a key role in assisting divers and Remotely Operated Vehicles (ROV) to assess the main area of wreckage on the seabed.
The Irish Lights vessel is specifically designed to assist with the maintenance and inspection of lighthouses and marine buoys in difficult weather conditions.
Blackrock Island lies 12km off Blacksod, Co Mayo, where the search and rescue teams are based.