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Heavy Fliers and Fuel Consumption

Q: According to a new study by the Centers for Disease Control, the average weight of Americans increased 10 pounds in the 1990s. Heavier fliers, says the report, require planes to burn more fuel, which in turn drives up fares. I find it hard to believe that the theoretical extra ton or two from chubby butts would seriously change fuel consumption. Am I wrong?

More weight means more fuel; there’s no way around it. Two-hundred passengers on a given flight, at an extra ten pounds each, means 2,000 added pounds. Specifically, the CDC states that in the year 2000, US airlines had to burn 350 million extra gallons of fuel, at a cost of more than a quarter billion dollars, to haul the added weight of ever-widening Americans. That extra fuel released an estimated 3.8 million tons of climate-changing carbon dioxide into the atmosphere.

Those are, if I may, pretty fat numbers, but they deserve some perspective. In the case of a fully-loaded 747, which has a maximum takeoff weight close to 900,000 pounds, the sum heft of an overbooked cabin (about 400 well-fed souls) represents less than 10 percent of the total, which mostly consists of fuel (about 400,000 lbs), freight, and the vessel itself.

That ratio isn’t so impressive with every model, as the 747 has outrageous economies of scale. Generally, the smaller the aircraft, the more your girth matters. With the 747, our extra ten pounds equate to a mere .46 percent of the max allowable weight. In the case of a 19-seater, it’s about 1.2 percent.

That’s not to downplay the significance of those 350 million extra gallons; only to point out that the weight of the passengers may not be as crucial to overall efficiency as you think. A less than optimum cruising altitude, for instance, can burn a lot more fuel than the expanded waistlines of those on board.

But for good measure, at least in this country, the airlines have turned proactive by refusing to feed you.

As for “driving up fares,” while the impetus is there in concept, fares remain cheaper than ever. Mean ticket prices in today’s dollars are the cheapest they’ve been since 1987. Adjusted for inflation, they are the lowest ever.

This article is part of a collection that originally appeared on Patrick Smith, 38, is an erstwhile airline pilot, retired punk rocker and air travel columnist. His book, Ask the Pilot (Riverhead) was voted “Best Travel Book of 2004” by Patrick has traveled to more than 55 countries and always asks for a window seat. He lives near Boston.