Poor weather conditions off the west coast are hampering efforts to locate the black box of the missing helicopter Rescue 116.

A signal from the black box was picked up yesterday afternoon and investigators are hoping it will lead them to the suspected crash site.

Three crew are still missing - Mark Duffy, Paul Ormsby and Ciaran Smith. 

A 4th crew member Dara Fitzpatrick was recovered from the water on Tuesday.

Declan Geoghegan from the Irish Coastguard has been giving Susan Keogh this update: