Sen. Charles Schumer, at a news conference Sunday in New York, wants to require the FAA to establish seat-size standards for commercial airlines. (Julie Walker/AP)

In a nation of expanding belt lines and buttocks, airline seats are bucking the trend toward bigger bottoms by shrinking in size.

Nowhere is the squeeze more passionately felt than on Capitol Hill, whose elected inhabitants jet home to their districts in far-flung states on a great many weekends.

“We have been squeezed long enough,” said Rep. Steve Cohen, a Tennessee Democrat who flies home to Memphis.

Cohen says his desire to end the squeeze has little to do with his own comfort or that of the 1.7 million Americans who fly within the United States each day. He says it’s all about safety.

“There will be a crash, and there will be people who will not be able to get out of an airplane,” he said at a recent House hearing.

His attempt to amend a bill so that the Federal Aviation Administration could study whether tighter seats and narrowing distance between rows posed a risk died in committee, but the issue was revived this week when Sen. Charles Schumer (D-N.Y.) said he would push for FAA action in the Senate.

Schumer said passengers are packed in “like sardines.”

“There’s been constant shrinkage,” he said. “They shouldn’t be cutting inches of legroom and seat width. It’s time for the FAA to step up and stop this problem from continuing.”

The problem of the shrinking seat has been exacerbated by the nation’s other problem: People are getting bigger. Almost 79 million Americans are obese, 35 percent of the population, and the number is projected to reach 50 percent by 2030.

The Centers for Disease Control and Prevention says the average weight of a woman these days is equal to that of the average man in the 1960s: 166 pounds. The average man now weighs almost 196 pounds.

Seat a row of average men in economy class on a Boeing 777, and you’re looking at almost 1,800 pounds. The average seat belt is about 40 inches long, and the FAA requires flight attendants “to discreetly offer” a 24-inch seat belt extender to passengers whose girth demands one.

As people have grown, airline seats have shrunk. In the 1970s, the average cheap seat was 18 inches wide. Now it’s about an inch and a half less. In the old days, there was almost a yard of distance between rows in the economy section. Today it’s about 31 inches.

People who pay more for business or first class get more room to breathe. There is enough variation among airline seats that the website TripAdvisor provides a lengthy list of what fliers can expect.

For the airlines, it’s all about competition. They went through a lean time after 9/11 and then the recession, but after bankruptcies and consolidation they have returned to profit. They think the FAA should focus on safety issues — like whether a plane could be safely evacuated in an emergency — but let discerning passengers decide whether they’re comfortable. If people feel too squeezed, they contend, they’ll select another airline.

Jonathan Grella, executive vice president of the U.S. Travel Association, says it’s not so easy for passengers to be so selective.

“It’s not just limited to seat size; it’s limited options,” Grella said. “Not only are we down to basically the big four [airlines], but essentially they have carved up the country, so it’s not like you’re getting head-to-head options to get from point A to point B. You’re going to get a seat of a certain size, and that’s about it.”

Cohen’s amendment to the House FAA bill failed, in part, because other committee members said a provision already in the bill required the FAA to study whether airplane evacuation plans were adequate.

But his push for a more targeted study of whether shrinking seat size and distance between rows was a risk found plenty of sympathy from his colleagues.

“Boarding a plane has become a battle between passengers to secure space in the overhead compartments to avoid baggage fees,” said Rep. Janice Hahn (D-Calif.), who co-sponsored Cohen’s amendment. “People are getting into fights over use of products like the Knee Defender, a gadget that actually stops the seat in front of you from being able to recline.”

And, said Rep. Rick Nolan (D-Minn.), it gets worse than that in close quarters.

“I’ve witnessed some of those fights,” he said. “A guy trying to squeeze into a seat and he caught a hold of a woman’s hair in the seat in front, and she’s screaming at him because he pulled her hair and he’s screaming at her.”

Plus, Nolan said, while safety is a paramount concern, comfort also is an issue.

“We’ve just gotten bigger as people. We’re wider, we’re taller,” he said. “I sat in a seat on my last flight [next to] a big-shouldered guy and, for crying out loud, he had his knees up around his shoulders and half his body was in my seat, and it was just unbelievably uncomfortable.”