A study conducted by Lufthansa found that at 30,000 feet, the perception thresholds for sweet and salty tastes drop by 30% to 40% compared to on the ground. Airplane food has long been a source of jokes, but behind the humor is a complex scientific explanation for why meals taste bland, flavorless -- or just different -- at high altitude. Understanding this begins with human physiology and the unique environment inside a pressurized aircraft cabin.