Hundreds of passengers travelling from London Heathrow Airport to New Delhi were left shaken after an IndiGo Airlines jet made a dramatic U-turn over the English Channel following an onboard emergency.

Flight 6E4 had departed Heathrow shortly after 8pm on Tuesday and was bound for Indira Gandhi International Airport when the crew declared an emergency just minutes after take-off, forcing the aircraft to abandon its 4,000-mile journey and return to London.

The Boeing 787-9 Dreamliner was expected to cross Europe and the Middle East before reaching India. But flight tracking data showed the aircraft had not even reached the coast of France before it turned around and headed back towards Heathrow, The Mirror reported.

Flight tracking data shows that as the aircraft reached the English Channel, the flight crew halted its climb at 24,000 feet before issuing a squawk 7700 emergency code.

The code is an international signal for a general onboard emergency and lets Air Traffic Control (ATC) know the aircraft requires priority handling. After broadcasting the code, the crew turned the plane back towards British airspace.

Declaring an emergency gives an aircraft priority handling from air traffic control, allowing it to receive expedited clearance to land and ensuring emergency services are on standby if required.

The squawk 7700 code is used to indicate a general emergency and can be triggered by a range of issues, including technical faults, medical incidents, severe weather, or other operational concerns.

The aircraft landed safely back at Heathrow and, by 9.37pm, had taxied to a remote stand while accompanied by airport fire crews. IndiGo and Heathrow Airport have both been approached for comment but are yet to respond.

Source: Nottingham Post/The Mirror