A plane travelling from Rome to New York declared a general emergency and diverted to land at Heathrow Airport.
Alitalia Airlines flight AZ698 was diverted to the West London airport after declaring an emergency over France.
The flight, which left Rome at 10.37am on Sunday (February 16), was due to land in New York at 2.25pm.
But at around 11.30am the flight declared a general emergency and began a descent over the English Channel.
Met Police officers got onto the plane as it landed and detained one of the passengers.
A spokesperson said: “police were called to Terminal 4, Heathrow Airport to a report of an unruly passenger on a flight from Rome to the US.
“The man was taken off the plane when it landed and detained under section 136 of the Mental Health Act.”