As a frequent flyer since birth, I've eaten many an economy class airplane meal, and they've been uniformly terrible. And the few times I've had the chance to fly business and first class, I was very disappointed with the meals. The secret to flying in the other sections of the plane is plenty of free booze, not severely improved food. I always assumed the food was crummy because the airlines were trying to save money, but in these days of bring your own, I've noticed the food I bring from home (fresh salads from Whole Foods that I normally love, or my own home-made sandwiches, which tend towards excellence) taste lackluster at 38,000 feet.
Scientists decided to study why this was the case, and hit upon one consistent issue: the noise. Anyone who has tried to listen to an iPod on a flight knows that you pretty much need to put the volume on the highest level to hear your tunes, whereas on the ground, that volume would be obnoxiously loud. That's because of all the "white noise" caused by the plane's engines. This noise may be the reason food tastes worse in the air (even though airplane food caterers notoriously overspice their food). NASA astronauts have similar problems with loss of food taste when on missions, and they are also provided with heavily flavored foods.
In a small study of 48 participants through the University of Manchester in England, each participant was given fatty, salty, and sweet foods to taste first while sitting in a quiet room and then again while they wore headphones that produced "white noise" equivalent to an airplane. In the noisy session, participants rated food as less sweet or salty than it actually was — and oddly enough, they rated it more crunchy.
"The evidence points to this effect being down to where your attention lies — if the background noise is loud, it might draw your attention to that, away from the food," Dr. Anthony Woods, one of the researchers, told the BBC. So, you could be eating a gourmet meal while on a flight, but the background noise could be distracting enough to make it taste like refrigerator leftovers.
Read the original study here, in the Journal of Food Quality and Preference.