In micro, I use a supplemental text, The Economics of Public Issues by Roger Miller, Daniel Benjamin and Douglass North. This WSJ article touches on two chapters from that book.
One chapter is about obesity and why it has been rising in the U.S. Mainly because our jobs have gotten more sedentary while the cost of food has fallen. People burn fewer calories while consuming more.
Another chapter is about airline safety. It mentions that customers do punish less safe airlines by flying with them less. It also mentions that we should keep adding safety features as long as the marginal benefit is greater than the marginal cost. But with a change in circumstances, it might change the efficient level of safety. With people getting heavier, that could mean more safety limits. So the cost of keeping flying safe is going up, but it might be justified if the circumstances have changed that make it more dangerous (heavier passengers).
Excerpts from the article:
"Passengers keep getting bigger. Now airlines must account more accurately for that.
The Federal Aviation Administration is requiring updates to passenger and baggage weight estimates that airlines use to keep each flight within airplane safety limits. Each U.S. airline must submit a plan by June 12 explaining which average weights for passengers and baggage they’ll use, down to phones and clothing, and how they estimated those weights. The FAA must approve each airline’s plan.
Airline officials say the weight estimates used for passengers and baggage are going up between 5% and 10%. That will affect some flights, possibly requiring that more passengers get bumped or more baggage left behind. Impact is likelier on unusually hot days and in cities higher above sea level, when the weight an airplane can safely carry is reduced because wings won’t generate as much lift. Flights into stiff headwinds that require more fuel also may face more weight issues."
"The FAA says it’s pushing the change to make sure that aircraft are loaded in accordance with airplane flight-manual limitations. The changes increase safety by reducing the possibility of an overloaded airplane.
While airlines are supposed to keep up with passenger changes, the agency realized that weight gains hadn’t been updated in years."
"One remedy for higher weights is to substitute larger planes in high-altitude markets in summer, but airlines have less flexibility to do that this summer."
"Alaska says it will increase the average estimates it has been using since 2013 by 7 pounds for adults, 2 pounds for carry-on bags and 4 pounds for checked luggage"
"Airlines can use the U.S. Centers for Disease Control and Prevention health survey results to estimate their typical passenger."
"The higher average weights might add more than 3,000 pounds to weight-and-balance calculations for a fully loaded 737 with 172 passengers. That’s significant—close to what 500 gallons of jet fuel weighs."
"The latest data from the CDC’s National Center for Health Statistics, published in January based on a 2015-2018 survey, puts the average male weight at 199.8 pounds and the average female weight at 170.8 pounds. In 2005, the last time the FAA required airlines to update, the same survey found that people weighed, on average, about 5% less: Men averaged 190.4 pounds and women 163.3."
"The Civil Aviation Authority of New Zealand requires Air New Zealand to hold a “weigh week” every five years to keep the average weight estimate current. The most recent weigh week happened in April."