A Boeing 737 carrying 144 passengers and six crew members was forced to carry out an emergency landing.
The pilot of the holiday flight from Belfast to Reus in Spain landed the aircraft safely shortly before midnight at Cork Airport in Ireland because of a suspected fuel leak.
"We activated our emergency plan but the plane landed safely," an airport spokesman said.
"The plane is grounded subject to inspection but it's not thought there was a leak."
Passengers were accommodated in hotels overnight.