The heartbroken family of Captain Dara Fitzpatrick, who was named as the first casualty following a helicopter crash off the west coast of the country, have paid tribute to her.
She was one of four crew members on board Rescue 116 which crashed six miles west of Blacksod.
She is survived by her three year old son.
It's believed that Ms Fitzpatrick is from Kilternan, Co Dublin.
Her family have led tributes to her.
"We are so proud of Dara's work and all she has done to save the lives of others over the years," they said in a statement to Today FM.
"We are completely heartbroken and we pray for the recovery of the other three crew.
"She is survived by her three year old son, her three sisters, brother and her parents."
Her sister, leading psychologist Niamh Fitzpatrick, also paid tribute to her on Twitter this afternoon.
"My brave sister Capt Dara Fitzpatrick lost her life. We are devastated. Please pray for recovery of 3 remaining crew".
Muckross Park College, where Ms Fitzpatrick attended, also paid tribute to her.
"It is with heavy hearts that we post this message. Capt Dara Fitzpatrick, class of 1989, died this morning doing what she loved #rescue116. Our thoughts and prayers are with her son. Her parents Mary Mulholland, class of 1962 & father John, twin sisters Niamh & Orla, class of 1986 , brother Johnny & younger sister Eimear, extended family & friends.
My brave sister Capt Dara Fitzpatrick lost her life in #Rescue116 crash. We are devastated. Please pray for recovery of 3 remaining crew.— Niamh Fitzpatrick (@NFitzPsychology) March 14, 2017
"We are all very proud of Dara's work & all she has done to save the lives of so many others.
"May She Rest in Peace."
The other three crew members on board the Sikorsky S92 helicopter, Paul Ormsby, Ciarán Smith and Mark Duffy are still missing.
Capt Fitzpatrick was pronounced dead in hospital, Gerard O'Flynn, VS&T Operations Manager of the Irish Coast Guard confirmed.
She was one of very few female civilian rescue pilots worldwide.
She featured in the RTE series Rescue 117 leading dramatic rescues by the crew at Waterford helicopter base.
Captain Fitzpatrick had over 20 years flying experience and was chief pilot in Waterford since 2002. She described her job as "challenging and exciting" during the filming of Rescue 117.
Captn Fitzpatrick spoke often about her love for her job.
Speaking to the 'Munster Express' in 2009, Capt Fitzpatrick said she was a native Dubliner, but more than happy to be living in Waterford at the time.
Dara told the newspaper she first went up in a helicopter at the age of 18, and "thought it was the business".
"And that, pretty much, was it.
“I got my own licence and I was working for a businessman for a year, year and a half when the Coast Guard advertised for co-pilots.
“That was at a time when Shannon was the only Coast Guard helicopter base was in the country so I applied for it and got it. I stayed there until 2002 and came over to Waterford and I love it here.”
“I had another few layers to deal with after I was taken on by Search and Rescue,” she added.
“They had to teach me to fly a twin engine helicopter since I was used to flying single engined. They had to teach me how to fly by instruments – which is another separate, long course.
“And before I could go anywhere near Search and Rescue, I had to get used to flying the helicopter with two crew because I was used to flying in my little helicopter all by myself, so I went to Aberdeen for a year to fly onto oil rigs.
“So by the time I got taken on, it had taken a good year to get me ready to sit in the left-hand seat as a co-pilot.
“But then even when I started, for the first while you’re hanging out the back seat of it – you’re just so far behind it because when the jobs come in, everything is happening so quickly.”
In January 2008, Capt Fitzpatrick appeared on a video entitled 'Find A Balance Dare To Dream' DVD.
It was produced by the Irish Bishops' Conference and it covers the issue of alcohol and the challenge of moderation.
The production, which was aimed at young people, saw Capt Fitzpatrick stress the importance of finding balance in her job and how she took her responsibilities.
"When I was about 18 or 19, all I wanted to do was economics or business or something. Didn't get the points I wanted to at school - just didn't work hard enough - and I heard an ad on the radio for a helicopter.
"I went up in a helicopter and that was it. I was hooked.
"Most people go 'oh there's so many buttons and dials and things', but it just takes a little bit of coordination.
"There are so many variables in this job. Like when we get a call here, you know the Coastguard will say there's a person injured here or fallen off a cliff in Dublin or something like that, you will have to in about two or three minutes, make a decision on whether we can go there and back and what fuel do I need.
"We can go up and save loads of people but there is no point in doing that if we can't get back. You just have to be able to think on your feet and also think about the consequences of making a decision. You have to be able to get back to land.
"I'm doing this about 15 years now which is a fair amount of time but it doesn't make any difference; it will still kick you in the ass. It really will. You will go along and you'll do loads of really, really good jobs and then one time, you will get a kick in the ass and it kind of wakes you up. You can't relax.
"The thing that I find the hardest is that everybody thinks it will never happen to them and again, you're picking somebody up out of the water. You probably don't think so much about the casualties, because you can't. You can't afford to. Because sometimes you might pick somebody up and you have another two to three hours transit with a badly injured casualty or a body in the back. When you drop them off to hospital or bring them to a quay or whatever, when that flight is over, you've got to turn the page and move on. And you can't really think about it too much."
She was also prominently featured in RTE's documentary Rescue 117 documentary.
"You never know what you are going to face, you could be called up to the mountains, you could be called because someone has fallen off a cliff. You could be called at 2 o'clock in the morning being called to an injured fisherman on a boat," she said on camera during the documentary.
"There is huge variety here, you really don't know what you're facing. I think most of us enjoy that. That's teh bit of the job that we actually like because you just don't know what's going to happen for the next few hours."
Speaking today Gerard O'Flynn said: "It is with our deepest regret we can confirm one of the pilots was Captain Dara Fitzpatrick.
"Dara has been pronounced dead.
"Dara was the most senior pilot and has been with the company for close on 20 years.
"Outside of her work as a pilot she did an enormous amount of work on water safety and was always available to do school visits and promote water safety.
"For all of us involved in the Coast Guard and for particularly her family it has come as a complete shock.
"And we want to extend our sincere sympathy to all her family and her flying colleagues in the CHC and simply to everybody who knew her.
"The operation is continuing, and we are continuing to recover wreckage out there.
"The whole operation is being done in conjunction with the Air Accident Investigation Unit who have been on scene all morning."
Contact was lost with the rescue chopper at approximately 1am on Monday morning.
The Dublin-based crew had been providing top cover for another Coast Guard helicopter Rescue 118 that was performing a medical evacuation (medevac) off the coast of Mayo.
Rescue 116 was returning to base when it fell out of contact.
A search operation got underway and a large amount of debris was found.
Capt Fitzpatrick was recovered from the sea and airlifted to hospital.
A multi-resourced search operation is underway in the area and debris has been recovered and brought to storage.
The recovery of the flight recorders, or the black box, will be crucial to determine what happened.
The Irish Air Corp Casa aeroplane, fishermen from all over the area, naval personnel and garda divers have all been on the scene today.
The LE Roisín arrived at the scene shortly after 9am.
Speaking at the lighthouse in Blacksod this morning, Gerard O'Flynn said that a number of vessels are currently involved in the search operation.
"At the moment the search is ongoing and it's been coordinated by the rescue coordination centre in Mallon. We're rotating the two coast guard helicopters in Sligo and Shannon. Ballyglass and Achill RNLI are assisting the search. Six fishing vessels and the naval ship, the LE Roisin are also involved," he told Independent.ie
A small amount of debris has also been recovered from the shore near the Blacksod lighthouse, as Gardai, Coast Guard members and investigators remain at the scene.
Gary Bohan from Belmullet, who is involved in the operation and spent the morning recovering debris in a rib, said he had never come across an aviation accident of this scale.
"We got involved at about 9am this morning. The conditions are bad. The debris is scattered across about two miles. The biggest part that came out is about half the size of a (truck) dirt panel.
Asked if it's a hard operation to be involved in, Mr Bohan said: "We're just trying to do our bit for the community. Doing our best that's all we can do.
"On the aviation side of things I've never seen anything like this. I've seen boats sink and tragedies like that but nothing on this scale. We're heading out again later on. The size of the area is getting bigger. The site at the moment is two square miles, but as the day gets on it's only going to get bigger and larger and larger, because the debris is scattering. It will definitely be floating north. Hope to God something will come a shore."
Speaking on RTÉ's Morning Ireland, Coast Guard director Eugene Clonan described today as a "dark day for emergency services".
He said that hopes are fading for the three missing crew: “At this particular point in time, our hopes are fading of finding the remainder of the crew."
Coast Guard sources said there was no evidence that the crew of the stricken helicopter had attempted to send a mayday call.
This would suggest that whatever happened, the crash was unlikely to have been caused by a mechanical fault.
But the sources stressed that it was too early in the investigation to speculate on the cause.
Tributes have poured in with Taoiseach Enda Kenny and Michael D Higgins expressing their sympathies.
Speaking in Washington Taoiseach Enda Kenny extended the "deepest sympathy" of the Government to the family of Captain Fitzpatrick.
Mr Kenny said he knows the area of the Mayo coast where Rescue 116 went down well.
"Obviously the search continues and on behalf of the Government again we pay our respects to the family of Dara Fitzpatrick. The search continues for other crew members.
"Clearly in the analysis and investigation into this we want to uncover what exactly happened in respect of the lack of communications and loss of contact with Rescue Helicopter 116," Mr Kenny said.
He told reporters that he learned about the lack of communications from the rescue team late last night.
The Taoiseach has been briefed on the unfolding situation by Transport Minister Shane Ross and the Chief of Staff for the Defence Forces Mark Mellet.
"The Irish Coast Guard have been exceptionally professional and competent in their work over many years.
"Last year alone over 2,500 incidents were directed by the Irish Coast Guard," he said.
"Obviously the rescue agencies are now coordinating their search in the locality, assisted by the Achill Lifeboat and local fishermen. Obviously Gardaí and the Defence Forces are in the area."
President Michael D Higgins has also paid tribute to the late Coast Guard member.
"Today marks a dark day in the history of the Coast Guard / Garda Cósta na hÉireann, with a member of this important service losing her life while providing assistance to others," he said.
"On behalf of the people of Ireland, may I pay tribute to Captain Dara Fitzpatrick who died today.
Health Minister Simon Harris has also paid tribute.
"It is striking that on a bright spring day such a dark cloud hangs over Ireland," he said.
"The crew of Rescue 116 represent all that is good about our country - they epitomise courage, bravery, selflessness and dedication to the welfare of others.
"These traits were all on display again overnight on our West Coast.
"This crew joined their colleagues in an effort to help a fishing vessel crewman access medical care. We now know that, tragically, Captain Dara Fitzpatrick has passed away.
"Often at times of great difficulty and sadness, we see people pull together - this has been so evident today as the ongoing, collective effort of our emergency services and the local community work together on this search mission."
Last September brave volunteer Caitríona Lucas (below) became the first coast guard member to die in the line of duty.
Ms Lucas, an active member of the Doolin coast guard in Co Clare, was part of a search and rescue operation in Kilkee when the tragedy struck.
More than 400 lives were saved last year by the service. The rescue missions were among 2,500 incidents co-ordinated from the agency's main bases at Dublin, Malin, Co Donegal, and Valentia, Co Kerry.