SWISS skipped a valve fix to save money — 8 years later a decompression forced a mayday

In 2016, Airbus issued a safety bulletin recommending airlines replace the skin check valves on its A330 aircraft after receiving reports of failures. The one-way valves stop pressurized cabin air from escaping through the fuselage skin.

SWISS considered the recommendation in 2017 and decided against replacing the valves on its fleet, citing cost. The airline judged the existing valves reliable enough, even though the aircraft were already due for a mandatory 24-month inspection of the same components — a routine that would have made replacement straightforward to schedule.

On 13 September 2024, flight LX-18 from Zurich to Newark, carrying 205 people, suffered a pressurization failure during its initial climb when a damaged skin check valve gave way. The cabin could not pressurize; the crew deployed oxygen masks, declared a mayday, and descended at 5,000 feet per minute before returning to Zurich for an overweight landing. Nobody was injured. Investigators later called the 2017 decision not to replace the valve "incomprehensible from a safety perspective."