A 19-year-old German national is still being questioned by gardaí investigating the circumstances that led to the grounding of an American airliner at Shannon.
He was arrested under the provisions of Section Three of the Air Navigation Act of 1975 and is being held at Shannon Garda Station.
Gardaí were believed to be awaiting the results of forensic tests.
It is understood the person detained may have been a passenger on the plane.
The Delta Airlines Boeing 767, with 147 people on board, had been en route from Frankfurt to Atlanta when a note was found claiming there was a bomb on the flight.
Gardaí and army bomb disposal experts who searched the plane at Shannon found nothing suspicious.
The plane later resumed its journey, taking off from Shannon just after 3pm.
