British Airways flight to Chicago drops 28,000 feet, returns to London

A British Airways flight from London to Chicago descended 28,000 feet in about seven minutes after declaring an emergency over an unspecified technical issue before turning back and landing safely at London Heathrow Airport, reports NBC News.

The Boeing 777 took off from Heathrow at 12:15pm local time on Monday but began descending around 30 minutes later while flying over Ireland, according to flight-tracking website FlightAware.

The aircraft descended from 36,000 feet to 9,000 feet during the rapid descent.

It then turned back towards London and spent around four hours flying over the Bristol Channel before landing at Heathrow at about 5pm local time.

"The aircraft landed safely after our highly-trained pilots returned to Heathrow following a technical issue," British Airways said in an emailed statement.

"Customers disembarked the aircraft normally and our teams are working to get their travel plans back on track as quickly as possible," the airline said.

Heathrow did not immediately respond to a request for comment, according to NBC News.

Passengers affected by the incident are likely to be provided with hotel accommodation by the airline until alternative flights can be arranged, in line with guidance from the UK Civil Aviation Authority.

The incident comes amid recent scrutiny of Britain's National Air Traffic Service (NATS) after two technical problems within two weeks caused major delays at several UK airports and led to hundreds of flight cancellations.

NATS attributed those disruptions to software issues.