AAIB investigation to Airbus A340-642, G-VGAS
Warning of excess cabin altitude during the cruise, En route from London Heathrow Airport to John F. Kennedy International Airport, New York City, USA, 23 February 2017.
Summary:
During the cruise at FL 400, the crew received a warning of excessive cabin altitude. They descended and continued to destination. At the same time as the warning of excessive cabin altitude, a fault was recorded in a Cabin Pressure Controller and it was suspected that this caused the cabin outflow valves to open allowing the cabin altitude to increase.
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