An IndiGo Boeing 787-9 Dreamliner flying from London to New Delhi was forced to turn back to Heathrow after the pilots detected a technical issue shortly after take-off and declared a mid-air emergency, triggering priority handling by air traffic control.Flight 6E 04, operating from London Heathrow to Delhi’s Indira Gandhi International Airport on September 22, landed safely back at Heathrow, IndiGo confirmed. The aircraft has been grounded for maintenance checks and will return to service only after receiving the necessary clearances.The Dreamliner, bearing registration LN-FND, had taken off from Heathrow’s Runway 27R around 8.05 pm local time (UK) and was climbing towards its cruising altitude for the long-haul journey to Delhi when the situation developed.Flight-tracking data showed that as the aircraft reached the English Channel, the crew stopped its climb around 24,000 feet.Soon afterwards, the pilots transmitted squawk code 7700, the internationally recognised transponder code used to alert air traffic control to a general emergency aboard an aircraft.The emergency declaration prompted controllers to give the Dreamliner priority handling and clear its path back towards British airspace before its return to Heathrow.IndiGo said a technical issue had been detected shortly after departure and the pilots decided to return in accordance with standard operating procedures.“Following standard operating procedures, the pilots decided to turn back and landed the aircraft safely at the London Heathrow Airport,” an IndiGo spokesperson said.The airline did not disclose the precise nature of the technical issue.A 7700 declaration does not by itself indicate the nature or severity of an emergency. It alerts ATC that an aircraft requires priority assistance, allowing controllers to clear airspace and coordinate its landing, with emergency services kept ready on the ground where required.IndiGo said the aircraft was undergoing maintenance checks and would resume operations only after securing all necessary clearances.Passengers affected by the disruption were offered hotel accommodation and were being shifted to the next available flights to Delhi, the airline said.“We regret the inconvenience caused to our customers and made all possible efforts to minimise it,” the spokesperson said, adding that the safety of passengers, crew and aircraft remained the airline’s “top priority”.