Passenger jet bound for US plunges 27,000 feet before circling for hours
Oxygen masks, a 27,000-foot drop and hours of circling: A retired fighter pilot breaks down what likely happened aboard a British Airways flight that descended suddenly.

TL;DR
- A British Airways flight bound for Chicago from London Heathrow experienced a sudden descent of about 27,000 feet.
- The aircraft returned to Heathrow due to a "technical issue," according to British Airways.
- A retired fighter pilot suggested the descent was likely an emergency procedure for a pressurization problem.
- The plane circled for hours before landing, possibly to burn off fuel and reduce weight for a safe landing.
- The flight pattern and actions taken were described as "by the book" for handling such an emergency.