A ping from the blackbox flight recorder from Rescue 116 has been located.
A massive air, sea and shoreline search has been ongoing off the Mayo coast, since the helicopter disappeared from radar screens in the early hours of Tuesday morning.
Captain Dara Fitzpatrick was confirmed dead yesterday, but Mark Duffy, Paul Ormsby and Ciaran Smith are still missing.
Members of the Air Corps, coastguard, navy and Gardai are all involved in the search operation.
Earlier, the Transport Minister met with the families of Rescue 116 in Blacksod as an intensive search continues for three Coastguard crew members missing off the Mayo coast.