A British Airways Boeing 747-400, performing flight from Boston (USA) to London Heathrow (UK), reported smoke in cockpit.

• Aircraft was enroute at FL390 about 100nm north of Moncton (Canada) when the crew donned their oxygen masks, declared Mayday reporting smoke in the cockpit and decided to return to Boston.
• The aircraft descended to FL380 for the return and landed safely on Boston’s runway 33L about one hour later, the flight crew was still on oxygen masks until after landing.
• Initial information received by The Aviation Herald suggested the aircraft allegedly had experienced fumes in cockpit and cabin. All 10 crew were taken to hospitals.