The Boeing 737-800 registration G-FDZG from Tenerife was approaching Cardiff in the early hours of Saturday morning when the pilot reported the problem.
“He radioed Cardiff and said we were going to do an emergency landing.
“He said, ‘This is not a drill. Prepare for an emergency landing.”
According to reports there was a problem with the landing flaps which reduce the speed at which the plane flies and shorten landing distances.
Pregnant women were moved from the seats, as air hostesses told passengers to remove shoes and glasses, and the pilot circled above Cardiff for 20 minutes to burn off fuel.
Eleven fire engines were waiting on the runway when the flight landed at it finally landed at 3.10am, 40 minutes later than scheduled.
