A major operation is continuing to locate three missing crew members from Rescue 116.
Captain Dara Fitzpatrick was recovered from the water Tuesday, after the coastguard helicopter went down off the Mayo coast in the early hours.
She died in hospital hours later. Tributes have been paid to Captain Fitzpatrick.
Taoiseach Enda Kenny expressed "deepest sympathy" on behalf of the Government.
President Michael D Higgins paid tribute to her "on behalf of the Irish people".
While Transport Minister Shane Ross said she was "a woman of extraordinary courage and professionalism who made the ultimate sacrifice in the service of others".
Captain Fitzpatrick had been with the search and rescue service for more than 20 years.
She made Irish aviation history three years ago, when she flew the first all-woman mission for the service.
During the search Tuesday, the Coast Guard said debris was found spread over a wide area.
Debris found on Tuesday by search teams reads 'Coast Guard' | Image: Juliette Gash
The LE Eithne kept searching through the night, while a survey vessel is also carrying out a sonar search.
Navy and garda divers, Ballyglass and Achill lifeboats, the LE Roisin, a fixed wing aircraft and two helicopters are also involved.
Gerard O'Flynn is search and rescue operations manager with the Irish Coastguard.
He says visibility has been improving.
"The visibility has improved significantly, so that obviously has obviously made it much easier.
"In terms of the air resources, we have support from the Air Corps, we're using our own Coast Guard helicopters - we also have availability from the Commissioners of Irish Lights".
Day two of the search scene for three missing members of the Irish Coast Guard whose helicopter crashed while on a rescue mission off Co Mayo | Image: RollingNews.ie
Garda and Navy divers are on stand-by to assist in the search.
However, Superintendent Tony Healy says rough seas are making that impossible.
"Those decisions will be taken on a minute-by-minute basis, depending on the sea conditions.
"They change we'll be fully reassessing our ability to dive."
Supt Healy says the families involved are being kept informed.
"There's two investigations on going at the moment - there's the Air (Accident) Investigation Unit and there's a garda investigation.
"The families are being briefed by family liaison officers, and they're being kept fully up-to-date".
The Coast Guard is keen to stress that they are fully resourced, and is asking volunteers to stay away from the water.
