According to the Irish Independent, the Shannon-based coastguard rescue helicopter was dispatched on the 300-nautical-mile mission to retrieve a man in his 70s from a cruise liner en route to Cobh from the United States.
The distance was so great that the helicopter, the new Sikorsky S-92 with the call sign Rescue 115, was forced to land on an offshore oil rig 180km off Kerry to refuel.
While there the chopper experienced a technical issue and was grounded for safety reasons while an engineer was sent to the oil rig on board Waterford's Rescue 117.
However, in the meantime a second doctor on board the MS Marina determined that the patient - who was feared to have had a stroke - was in a stable enough condition to be transferred to hospital upon the ship's arrival in Cobh early today.
The Irish Examiner confirms that the casualty was a 79-year-old American.