From the Times of London (original behind paywall):
The Irish Coast Guard air crew that died in a helicopter crash off the north Mayo coast in 2017 was flying with inaccurate charts, faulty satellite locators and was at risk of fatigue due to demanding work rosters, an investigation is set to conclude.
Captain Dara Fitzpatrick, 45, and Captain Mark Duffy, 51, had been awake for more than 18 and 17 hours respectively when their Sikorsky S-92A helicopter crashed into Blackrock island off the Mayo coast in the early hours of March 14, 2017, killing both pilots and winch team Paul Ormsby, 53, and Ciarán Smith, 38.
Investigators have identified several causes contributing to the helicopter crash, which occurred at night and in poor weather nine nautical miles from the intended landing point at Blacksod, where it was due to refuel. Investigators believe the crew was “unaware” that the first waypoint on its programmed route was flying them directly to a “282ft obstacle”.
They also note that the first waypoint on the southerly approach to Blacksod lighthouse was almost coincident with Blackrock lighthouse, to the west, at 282ft.
The crew were working a 24 hour shift system and were dispatched to provide communication cover for a medical evacuation from a fishing boat which turned out not to have been made.
Full report due in “the coming weeks.”