A British Airways 747 flight from Houston to Heathrow was forced to make an emergency landing at Cardiff airport on Monday morning, it has been reported.
A full emergency procedure was launched with fire and medical services.
The aircraft was carrying 140 people and landed at 10:40am, Wales Online said.
It is thought an instrument problem was to blame.
A spokesperson for BA said: "As a precaution, the Captain of the flight from Houston to Heathrow, decided to divert to Cardiff after indications of a potential technical problem.
"The flight landed normally and engineers at Cardiff are now assessing the aircraft.
"We apologise to customers for the delay to their journey."
A spokeswoman for Cardiff Airport said the flight returned to Heathrow Airport after the problem had been solved.
"The aircraft left at 13.30, returning to Heathrow with all the passengers.
"Engineers were on site when the aircraft arrived (at Cardiff International Airport) and the problem was solved."