A signal from the Rescue 116 Sikorsky S92 "black box" has been detected close to Blackrock lighthouse, some 13 km off Mayo's Mullet peninsula.
Irish Coast Guard operations manager Gerard O'Flynn and Air Accident Investigation Unit (AAIU)chief aeronautical officer Capt Jurgen Whyte confirmed a "weak" transmission had been picked up shortly after 4pm today during the continued search for three crew missing from the helicopter.
It was narrowed to an area some 50 to 60 metres southwest of the Blackrock lighthouse in some 40 metres of water, and the next stage will involving “homing and triangulation” to pinpoint its position, Mr O’Flynn said.
“It is a very faint signal - a chirp - and as you go towards it, it gets louder,” Mr Whyte said. “It is a bit of a needle-in-a-haystack situation, and you are trying to triangulate from different areas to get the loudest noise,” he explained.
“When you get the loudest noise, you know the wreckage should be beneath that point,” he said. However, it is not yet clear whether the black box is within the aircraft, he said.
Specialist equipment will now be used to home in on that signal, said Mr Whyte, a former Air Corps search-and-rescue pilot.
Some of this equipment would arrive with air accident investigators from Britain on Wednesday evening, he said.
Once a location is established, diving teams will be deployed- although the weather forecast for Thursday is not good.
The location - while “difficult” - is within the capabilities of the Naval Service and Garda diving teams, Mr O’Flynn said.
Mr Whyte described it as a “hugely significant step”.
“Other investigating authorities have spent months, literally, trying to do the same thing [locate black boxes]. We are very lucky that within less than 36 hours we have picked up what is a signal,” Mr Whyte said.
“What it means is the recorder has activated its beacon, and we are now using sophisticated equipment to home in on this signal itself,” he said.
“So we have to transfer a lot of sensing equipment from a large to smaller vessel, and, depending on conditions and swell, we will try and move that vessel in, and home in right on target in the hope that the wreckage will be directly within that area,” he said.
The signal was detected by smaller vessels using Marine Institute surveyors and equipment, as the area close to the rock is too rough and rocky for the 31 metre Celtic Voyager.
The research ship has been on location since first light with specialist equipment on board, including a high resolution EM 2040 multi-beam and a digital side scan.
These devices are usually deployed for seabed mapping and fisheries surveys, but can also scan the sea floor. The multi-beam has a range of 600m below water and over 100m on each side of the ship. The Marine Institute surveyors had also deployed two hydrophones to detect noise, and its team was providing the Irish Coast Guard with predictive models.
“We are attempting to go in, once its safe,” Mr Whyte said.
“It is in a difficult area just off Blackrock, in difficult waters in 40 metres of depth. We need to find a top point and we then have a fixed position, and then use a robot to dive down and actually locate the recorder. The hope is the recorder is with the wreckage,” he said.
Considerable amounts of wreckage are continuing to be brought ashore, and these will be examined in Gormanston, Co Meath, as part of the investigation, Mr Whyte said.
The AAIU is still at the stage of search, location and evidence-gathering, and has not yet started the investigation itself which would take some months, he said.
Mr O’Flynn said it was still a search operation at sea, and the LÉ Eithne would remain on the scene overnight.
“It’s a very difficult time for the families and very hard to give up hope that someone might be found,” he said.
“We are searching for casualties and evidence and anything that might figure what went wrong,” he said.
Belmullet Garda Supt Tony Healy said families were being kept fully informed of every stage of the search, working with Garda liaison officers.
‘Unthinkable and unspeakable’
The loss of the Irish Coast Guard helicopter and the fact of crew members being missing was "unthinkable and unspeakable" for the families involved, Minister for Transport Shane Ross said earlier.
Mr Ross, who arrived at Blacksod in Co Mayo to meet the relatives of the missing this afternoon, said it was a most grim day for the community.
Every possible resource in the State would be allocated to the search and to finding out what happened, he added.
There is still no clear indication of the cause of the crash, which occurred with Capt Dara Fitzpatrick, Capt Mark Duffy, winch operator Paul Ormsby and winchman Ciaran Smith on board.
Capt Fitzpatrick was recovered in a critical condition from the sea early yesterday and later died, and hopes have been fading for the safety of her three crew.
Capt Fitzpatrick (45), was the mother of a three-year-old boy. Her sister said it is "a consolation" to the family that she had "no regrets, that she did what she wanted". Niamh Fitzpatrick said on Wednesday her sister "loved her job, she worked hard, she was excellent at it".
At a briefing on Wednesday morning on Blacksod pier, Mr O’Flynn had paid tribute to support from fishing vessels and members of the public, but said safety was also important and there was no requirement for extra assistance at sea.
The Marine Institute's research vessel, Celtic Voyager, is on the scene and is using specialist multibeam sonar equipment. Marine Institute staff from the national seabed mapping programme, INFOMAR, are also assisting.
The Celtic Voyager's sister ship, the far larger Celtic Explorer, is on standby for deployment and has a remotely operated vehicle (ROV) which can be deployed to examine the seabed. The Irish Lights vessel Granuaile has also been positioned in the northwest to assist if and when required.
“They are engaging in a form of underwater mapping,” Mr O’Flynn said.
The two Naval Service patrol ships, LÉ Eithne and LÉ Róisín, are equipped with multi-beam echo sounders, while the Naval Service divers can also use ROV equipment.
The divers also have ultra short baseline equipment to listen for the helicopter transponders and black boxes. No mayday or satellite alert were picked up from the helicopter, its transponders or the personal locator beacons worn by the helicopter crew.
The Garda and Naval Service diving teams are evaluating the situation and assessing where they might dive, relying on information from the Celtic Voyager and the location of debris still being recovered. The depth of water varies from 10 metres to 50 metres in the 5 sq km (2 sq m) search area.
The Irish Coast Guard Ballyglass team is continuing a shoreline search, and picked up a small amount of equipment this morning, Mr O'O'Flynn said.
The priority was “still the human side, as we still have three missing persons”, he added, when asked about the search for the helicopter’s black box equipment.
“You have to be careful not to clutch at straws. We don’t have any specific leads.....we don’ t have any particular area that suggests we should be searching in point x or point y. We are just continuing to look for debris, look for pointers and for any parts of the jigsaw,” he said, focusing in a “relatively small geographical area”.
Belmullet Garda Superintendent Tony Healy said debris would be examined as part of two investigations, by the Air Accident Investigation Unit (AAIU) and the Garda.
"The families are briefed by family liaison officers from An Garda Síochána, so they are being kept fully up to date," Supt Healy said.
President Michael D Higgins described it as a "dark day" in the history of the Irish Coast Guard.
Speaking in Washington, Taoiseach Enda Kenny extended his sympathies to the family of Capt Fitzpatrick, and spoke of the “exceptionally professional” Irish Coast Guard personnel.
CHC Helicopters, which employs the air crew on a contract to the Irish Coast Guard, said it was devastated by what it described as a “tragic accident”.
The Dublin-based helicopter Rescue 116 was providing top cover, or support, for the Coast Guard’s Sligo-based helicopter which was tasked to undertake a medical evacuation of an injured fisherman some 240km west of Blacksod.
The Dublin helicopter lost communications shortly after it had issued a radio message at 12.45am confirming it was landing at Blacksod for a normal refuelling.
It issued no mayday and no satellite beacons were activated. Wreckage was sighted at sea by the Sligo helicopter on return from the medical evacuation, which was successful.
The Air Accident Investigation Unit is examining the wreckage as part of its inquiry, and hopes to recover the aircraft’s black boxes – the flight data recorder and cockpit voice recorder.
Aviation experts say the condition of the gearbox and other transmission components will be key to the investigation, which is the worst in Irish aviation history since the loss of four Air Corps crew when a Dauphin helicopter crashed on return from a rescue mission off the Co Waterford coast in July 1999.
Chief inspector for the AAIU, Jurgen Whyte, said the priority in the search now is to locate and recover the three missing crew members.
It is hoped the black box’s location beacon was triggered and that a search of the sea floor will locate it, he said.
Mr Ross was accompanied to Blacksod by Independent Alliance TD Kevin "Boxer" Moran and Belmullet-based Fine Gael councillor Gerry Coyle.
“I’m down here on behalf of the Government with ‘Boxer’ Moran to express the solidarity of the Government with the families at this awful hour in their lives and to say to the community here that we think what they are doing is absolutely wonderful, uniting by the families here today - and we want to express solidarity and sympathy with everybody involved and the Government’s great support for the effort that is going on,” he said.
“The idea that people whose purpose in life - whose motivation in life - is to save lives, have lost their own lives, makes it even more poignant than ever,” Mr Ross told reporters.
“These people have saved so many lives in the past and have now lost their own... it makes it a tragedy of proportions which are unimaginable,” he said.
“I have spoken to the Taoiseach about it and we agreed immediately that every single resource available in the State would be available to the families and to the people here to find those who are missing, and to establish what happened, and to alleviate the distress.
“There will be absolutely nothing left...everything possible will be done,” he said.
Mr Ross said it would be far too soon to speculate on what happened.
Mr Ross met officials from the Coast Guard and representatives of the rescue units at Blacksod lighthouse, before being taken with Mr Moran to meet the relatives of the missing crewmen.
There were emotional scenes as the family members embraced each other as they arrived, walking slowly together to a house close to the pier as the search continued out west to sea.