A British Airways Boeing 787-900, registration G-ZBKF performing flight BA-143 from London Heathrow,EN (UK) to Delhi (India), was enroute at FL350 about 20nm east of Brussels (Belgium) when the crew initiated an emergency descent due to the loss of cabin pressure, the passenger oxygen masks were released. The aircraft levelled off at FL100 and returned to London for a safe landing about 80 minutes after leaving FL350.
A replacement Boeing 787-900 registration G-ZBKC reached Delhi with a delay of 6:40 hours.
The airline confirmed a loss of cabin pressure prompted the release of the oxygen masks and the return to Heathrow.
The occurrence aircraft is still on the ground 31 hours after landing back.
On May 18th 2017 the UK AAIB reported the aircraft suffered a gradual decompression while enroute from London to Delhi and returned to Heathrow. An investigation into the occurrence is ongoing.