An inquest into the deaths of four Coast Guard aircrew off the west coast of Ireland has heard how the visibility in the moments before the crash was "very poor and dense".
The inquest, in Belmullet, heard how visibility dropped fast in the area moments before the crew were due to land at Blacksod to refuel.
Rescue 116 crashed off the County Mayo coastline in March 2017, during a search-and-rescue mission, after it struck Blackrock Island, 12 miles from the shoreline.
Captain Dara Fitzpatrick, the commander of the flight, was pulled from the sea in the hours after the crash and never regained consciousness, and the body of Captain Mark Duffy, the co-pilot, was taken from the cockpit 12 days later by Navy divers.
The bodies of winchmen Paul Ormsby and Ciaran Smith were never recovered, despite weeks of intensive searches of the seabed, surface and shore.