Dive teams are hoping a weather window will open on Friday to allow them to examine the wreckage of an Irish Coast Guard helicopter which crashed into the Atlantic over a week ago.
A remotely-operated vehicle (ROV) sent into 40m of water to film a specific area of seabed confirmed the aircraft is lying about 60m off Blackrock island, off the coast of Co Mayo.
The Sikorsky S-92 is believed to have hit the island before crashing into the sea in the early hours of Tuesday March 14.
Captain Dara Fitzpatrick, a 45-year-old mother of one, is the only one of the four crew to have been recovered from the ocean so far.
The other crew members, Captain Mark Duffy, Winchman Ciaran Smith and Winch Operator Paul Ormsby, remain missing.
The Irish Coast Guard said the Dublin-based Rescue 116 helicopter is lying on the seabed, in about 40m of water, on the eastern side of the island.
Search teams are hoping winds maintain from a northerly direction with swells around the island easing to below 3m, the safe limit for navy and garda divers to get into the ocean.
"Conditions are improving all the time," Declan Geoghegan of the Irish Coast Guard said.
"There'll be an exploratory dive hopefully. The ROV can only tell us so much. The human eye is much better. Once the divers go down they will have a much more positive idea of things."
It has not been confirmed if the remotely-operated vehicle has found the missing crew with the helicopter wreckage.
The helicopter is lying in an area from where signals from the black box flight recorder are being emitted.
The Granuaile is using Holland I and Holland II ROVs from the Marine Institute and the Irish Naval ship LE Eithne is co-ordinating the recovery operation with the support of the Irish Coast Guard, gardai, the RNLI and fishermen with local knowledge of conditions.
The Irish Lights Vessel is primarily used to place and service the 150 buoys off Ireland's shore.
It has a heavy-lifting crane as well as dynamic positioning technology, which allows it to remain in the same spot on the surface, much like an aircraft would hover, so divers or remotely-operated vehicles can be put into the ocean.
The underwater terrain, part of the lighthouse rock and dangerous underwater currents in the area are adding to difficulties around Blackrock but the forecast is for fair to moderate until the weekend with swells easing.
The ROV, attached to the ship by cables, has the ability to send back live pictures.
The AAIU has said it believed the tail of Rescue 116 hit rocks on the western end of the island, about 13km (eight miles) off the Mayo coast as it returned from supporting a rescue mission to refuel at Blacksod.
There was no indication of any danger moments before the Sikorsky S92 vanished, with the crew's final transmission: "Shortly landing at Blacksod."