An Aer Lingus flight from Amsterdam to Cork had to be diverted to Cardiff Airport after passengers reported fumes coming from the cockpit.
A full emergency was declared at Cardiff Airport for flight EI845 and fire trucks were scrambled.
The aircraft landed safely at 9.06pm and the 169 guests disembarked normally.
A spokesman for Cardiff Airport said: “The safety and security of staff and customers remains our top priority, and our team responded on landing as per emergency protocols.
“The airport is open and operating as normal with no impact on services.”
Aer Lingus sent a replacement plane to take passengers to Cork. That left Cardiff Airport at 1.10am.
An airline spokesman said the cause of the technical fault is still being investigated.
He added: “We apologise sincerely to our guests for the disruption to their travel plans.”
