The in-flight food airlines used to give you for free now costs $7.00. The price increase has done nothing to improve taste or quality. Those brightly colored yellow boxes are still filled with crappy tasteless snacks that have accumulated more frequent flyer miles than me. However, somebody with a Ph.D in food science thought that including yogurt on the menu would be a good idea. And now I’ll tell you why this isn’t so.
First, a little science background. Atmospheric pressure is the pressure at any point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location. Similarly, as elevation increases there is less overlying atmospheric mass, so that pressure decreases with increasing elevation.
For those of you with little or no comprehension of scientific principals, the above basically means that the higher above the Earth you go the lower the pressure. Eventually the pressure will decrease such that if you were exposed to sufficiently low pressure without protection, you’d explode. Every cell in your body would rupture simultaneously. No. Really. Most of us live at or near sea level (except you folks in Colorado.) At sea level, air presses against our bodies with approximately 15 pounds of force. The reason we don’t feel it and are not crushed, is because the pressure inside our bodies and inside our cells is pushing back with an equal amount of force – which is why we’d explode in the upper reaches of the atmosphere. Actually, we’d expand like a balloon and then explode in case you’re studying for an exam. If you’ve ever swum to the bottom of a pool or body of water, you’ve experienced the same situation and felt the increasing pressure in your ears. As you rise back up the pressure decreases. Same idea here with air instead of water.
The reason we don’t explode when we’re inside a jet airplane at 39,000 feet is because the inside cabin air is pressurized – well, sort of. You know that uncomfortable full feeling you get in your ears when you fly, that’s cured by swallowing? That’s the effect of the internal pressure inside your head trying to equalize with the much much much lower air pressure inside the jet. The cabin is pressurized, but the pressure is still much lower than it would be back on terra firma. I’m sure money is the reason the airlines don’t make you more comfortable at 39,000 feet.
So somewhere along the way, the corporate airline executive food geniuses figured out that yogurt would make a great snack at 39,000 feet. This proves one of two things. Either airline executives don’t eat yogurt, or they don’t fly in jets.
A little background on yogurt. All you really need to know is that it’s manufactured at sea level. Mr. Dannon puts it in a little plastic cup and seals it closed with a peel-away foil lid. I don’t know why this is, but there’s a little air gap between the top of the yogurt and the peel-away lid. Again, I’m assuming this has something to do with money. They don’t fill the damn thing all the way to the top. Damn it! Don’t the yogurt magnets know that this fluid-like dairy treat is being served at 39,000 fucking feet? If the yogurt containers were filled all the way to the top, we wouldn’t be having this discussion I assure you.
What happens is this. When the little foil lid is glued to the top of the yogurt cup, it traps air (or perhaps some inert gas) inside that gap, which happens to be pressurized at the normal sea level pressure of 15 pounds of force. The yogurt is shipped to the crappy snack food company and married up with the rest of the junk inside the cheap yellow boxes. Chill, load and fly. At approximately 39,000 feet, the pilot decides that it’s time to feed the suffering huddled masses and orders the flight crew to feed anyone willing to part with $7.00. The yellow boxes are handed out systematically. Dining begins.
It was my experience on a particular flight, that everyone got to the yogurt at about the same point in their meal as everyone else. But because the boxes were handed out row by row (working from the front of the plane to the back) there was a slight delay in the partaking of the yogurt. While I was about half way through my faux ham & Swiss on impossibly small rye (which only took 3 bites to eat) I heard a noise from about 3 rows in front of me. Just above the constant whine of the jet engines and through the fullness in my ears I heard a muffled, “Oh Shit!” Perhaps a minute later I heard it again, but more clearly this time. Perhaps only one or two rows in front of me. “Oh Shit!” I couldn’t imagine what the problem was, but from my cramped quarters, there was nothing I could do and wasn’t about to go exploring. The third time I heard it, it was clear. A quite perturbed “Oh Shit” came from the row in front of me. By now I’m seeing flight attendants walking by with handfuls of napkins, offering apologies somewhere several rows up.
I finished my sandwich and grabbed the yogurt. I wrestled the plastic spoon out of its sanitary envelope and placed it on my seat-back tray, which was not upright and in the locked position. I noticed that the peel-away foil top of the yogurt container was clearly bulging. It had a definite camber to it and was quite firm to the touch. Despite these visible signs (and a straight “A” average in science all through high-school and college) I failed to realize what was coming. Nothing registered whatsoever. This says a lot for the value of experience over book learning, mind you, which for me, was sorely lacking, as I had never eaten yogurt at any height above that of your average tabletop.
I grabbed the little foil tab and tugged. Nothing. I tugged harder and was immediately greeted by the sound of a wet fart and rushing air, and promptly followed with my own “Oh Shit!” as I watched about a tablespoons’ worth of yogurt fly out of the container, and splatter the front of my shirt. Raspberry surprise! Suddenly, my whole world made sense to me – the domino-like cascade of “Oh Shits”, the bulging foil top, the handfuls of napkins – the entire cosmos clicked neatly into place in the space of one second. I sat there stunned as comprehension poured into the top of my head – considering it all. And then it started again. The row behind me. “Oh Shit!” I smiled. I couldn’t help wondering whether this was the flight crews’ favorite part of their day “Yogurt Time!” Perhaps it’s me, but I was glad to be in on the joke, or at least a part of it. I had to admit, this was pretty damn funny, considering all of the circumstances that had to line up for this to happen just so. Science is cool – especially at 39,000 feet.