A passenger flight from Zurich to New York reportedly "declared an emergency'" while flying over the UK.
The incident occurred as the Airbus A330-300 flew over London on its way to the east coast of the United States.
The flight monitoring website Air Live reported: "A Swiss Air flight from Zurich to New York is declaring an emergency. Flight from Zurich to New York Newark has declared an emergency over London at 17:15 UTC.
"The Airbus A330-300 took off at 18h06 from Zurich and was supposed to land 8 hours later in Newark. The aircraft turned around and descended to 10,000 ft, heading South.
"The Airbus 330 (reg. HB-JHL) is a 11 year-old plane with 8 seats in first, 45 in business and 183 in economy class."
AirNav RadarBox is reporting that the plane has yet to take off from the Charles de Gaulle International Airport in Paris.
Monitors suggest it landed there at 5.50pm, reports MyLondon.
It comes weeks after an EasyJet plane had to make an emergency landing after a passenger was taken unwell on the flight from London Stansted.
Passengers were supposed to reach Belfast International in the afternoon but, due to the medical emergency, the pilot had to make a mid-air U-turn to Liverpool John Lennon Airport.
Emergency services were on hand there to offer assistance.
The plane's captain declared an emergency about an hour into the flight, by which time the aircraft was travelling over the Irish Sea.
It was diverted and halted at Liverpool for a while, until the pilot was able to continue the journey safely to the Northern Irish capital.
