The Shannon-based Coast Guard helicopter is on its way to evacuate an injured crewman off an Irish fishing vessel around 120 nautical miles (222 kms) west of the Blasket Islands.
The Valentia Rescue Coordination Centre got a mayday call from an Irish registered fishing vessel this afternoon.
The vessel had reported that a crewmember had suffered an injury onboard and needs to go to hospital.
A second Coast Guard helicopter is providing support because of the distance involved.
They are expected to reach with the fishing vessel at around 5.30pm.