The skies are desolately quiet without the crew of Rescue 116
For the third day since the tragic loss of Rescue 116, white waves thrashed on the Atlantic off the coast of the Mullet peninsula, making diving impossible.
At the best of times, conditions are treacherous at remote Black Rock, a rocky mound rising 80m above the sea, on which a lighthouse was perched in the 1860s.
There could scarcely be a worse location in terms of mobilising a search-and-recovery operation.
But a critical three-hour window between low tides on Monday could prove to be the break that the search teams have been waiting for amid mounting anguish for the devastated families of the three missing crew members of Rescue 116.
The search has now been narrowed to a small section of the ocean, some 100m by 80m at the rocky base, where the signal from the black box was detected.
The shores of Blacksod Bay are being combed by a volunteer crew of around 250 people who have come to do what they can. In the meantime, all the suffering families can do is wait.
For Rescue 116, Monday night's mission had been a fairly standard operation - almost identical to one carried out days beforehand.
On March 8, the helicopter provided top cover to R118, in a medical evacuation of a Russian fishing vessel, after a crew member suffered a sudden illness.
In that mission, both helicopters refuelled at Blacksod prior to transiting to the scene amid early-morning conditions described as "challenging".
On Monday night, it was again a fisherman working on board an international blue whiting fleet, some 250km off the Mayo coast but who, this time, had been injured, which saw R116 again called to provide top cover duty. The weather was, again, poor, with fog and driving rain.
Vincent Sweeney, the principal keeper at Blacksod lighthouse, was expecting the same two helicopters to refuel. As was usual, his son Simon and nephew, Fergus, helped him to lay out the cable for a swift operation expected to take 15 minutes.
Vincent told Simon and Fergus to head home, as it would be 11pm at least before he was expecting them.
But at around 1.20am, Simon roused Fergus with an urgent message: R116 had gone down.
An ambulance already stood station at Blacksod lighthouse, along with Irish Coast Guard volunteers.
R118, which landed the injured fisherman to safety, had spotted wreckage floating out at sea. There had been no mayday signal.
Malin Head Coast Guard tasked the Shannon helicopter, along with an Air Corps fisheries protection aircraft, RNLI lifeboats from Ballyglass and Achill, and several local fishing vessels, to mount a search operation.
A casualty, later confirmed as Captain Dara Fitzpatrick, was spotted in the water. Her condition was critical, and she was confirmed dead at Mayo University hospital in Castlebar.
Still missing are the remainder of her crew - chief pilot Mark Duffy and winchmen Paul Ormsby and Ciarán Smith.
Capt Fitzpatrick (45) was dubbed the poster girl for the Irish Coast Guard service because of her TV appearances on an RTÉ series on the rescue services.
Courageous, vivacious and beautiful, she was a hero for trainee pilots at Waterford where she was based.
"She signified what was possible for women in aviation. I just thought she was fantastic," surgeon Geraldine Cunniffe-Conlon, who learned to fly at Waterford, said.
A week-and-a-half before the tragic accident at Black Rock that claimed her life, she took part in the most gruelling training exercise dubbed 'the dunk' - helicopter underwater egress training, or HUET, involves being put upside-down underwater in a helicopter simulator, pitch-black with churning waves and rain.
The goal is to find your orientation before pushing on the window to escape.
"They get them to jump off a high board and they're terrified. It goes against every human reaction," Capt Fitzpatrick's sister, Niamh Fitzpatrick, said. "But they knew they need every ounce of training, so they did it.
"Dara had been dreading it and she was so happy that she wouldn't have to do it for another three years. And then a week-and-a-half later, the helicopter goes down," she said.
Niamh believes that the family had in some way felt a lessening worry for Capt Fitzpatrick as the years had gone on.
"In the early days we would have been very worried when she was going out, especially in stormy weather, you'd have a band of fear going around your middle," she said. "I think we did feel that worry diminish, because when we got that call on Tuesday night we got a shock - it was like being hit by a truck."
Capt Fitzpatrick began her extensive career as a helicopter pilot in Shannon in the 1990s and was "probably the most experienced pilot in CHC", the company which provides helicopter search-and-rescue services for the State.
Winchman Ciarán Smith (38), a father-of-three, was a keen cyclist and former Air Corps member who completed the 2,200-kilometre ultra-cycling event, Race Around Ireland, in 129 hours and 43 minutes to raise €10,000 for children's cancer organisation, Aoibheann's Pink Tie.
Pilot Mark Duffy (51), a father of two, lived in Blackrock, Co Louth, and joined the Coast Guard having trained in the US, where he worked with the Californian Coast Guard for seven years.
His wife Hermione Duffy posted an emotional message on Facebook to thank people for their "love and compassion", describing him as her hero and her soulmate.
Several hundred people attended a candle-lit vigil in his home village last night.
"There is so much emotion in the village and everybody wants to reach out and give their support to the family," Fr Brian White said.
Paul Ormsby (50) was born in Oranmore road in Ballyfermot, Dublin, and lived there all his life.
He was a devoted carer to his mother Kitty until her death some years ago. He, too, was a former member of the Air Corps and saved countless lives in a career spanning almost 30 years.
As a team aboard R116, they were the protective red dragon of the Dublin coast, providing a beacon of hope and care.
The skies are desolately silent without them.