Source: Simon Hradecky | www.avherald.com

A British Airways Boeing 777-200, registration G-VIIG performing flight BA-238 from Boston,MA (USA) to London Heathrow,EN (UK), was climbing out of Boston when the crew requested to level off at FL200 while they were investigating an unusual odour in the aft cabin. A few minutes later the crew advised the odour had disappeared and continued the climb, however, the crew again requested to level off at FL280 now reporting there was smoke on board of the aircraft. The crew decided to return to Boston for a safe landing about 55 minutes after departure.

Maintenance identified a faulty air conditioning system as cause of the odour and smoke.