A British Airways flight turned back to London's Heathrow airport overnight while enroute to Nigeria's capital Abuja.
The airline says the crew had to care for an unwell customer on-board.
The aircraft landed safely and the flight was met by the emergency services.
The flight, BA83, departed Heathrow for Nigeria just before 22:30 on Thursday night.
Flight Radar shows it turned around over Le Mans in France and returned to UK airspace after appearing to declare an emergency.
The London Ambulance Service says it was called at 23:23 and sent an ambulance crew to the airport.