Commercial aircraft cabins are pressurised, but not to sea-level conditions. Most are pressurised to the equivalent of an altitude of around 6,000 to 8,000 feet. At the same time, cabin humidity is usually much lower than what people experience on the ground.

This combination dries out the nose and mouth, reducing the ability of the taste buds and smell receptors to work at full capacity. Since smell contributes significantly to how we perceive flavour, food can seem noticeably less vibrant in the air.

​Several studies, including research commissioned by the German airline Lufthansa and conducted by the Fraunhofer Institute for Building Physics, have found that people’s perception of sweetness and saltiness can decline in flight-like cabin conditions. As a result, foods that taste well-balanced on the ground may seem under-seasoned in the air.