WASHINGTON — If the world seems to be closing in around you, check to see if you’re on an airplane.

Could that wall of seat backs have inched closer? Are those armrests pinching even tighter?

It’s not your imagination. They have and they are.

The Federal Aviation Administration promises it soon will decide whether to step in and determine just how much room you deserve when flying with a commercial airline.

It’s all part of what D.C. Circuit Judge Patricia Millett called “the Case of the Incredible Shrinking Airline Seat.”

“As many have no doubt noticed, aircraft seats and the spacing between them have been getting smaller and smaller, while American passengers have been growing in size,” Millett said in a July ruling ordering the FAA to review seat sizes and legroom.

The FAA said it will soon announce its decision but declined to specify when.

The case came about because a nonprofit group, the Flyers Rights Education Fund, asked the FAA for rules to prevent the passenger squeeze from continuing.

The FAA considers itself a safety agency rather than a creature-comfort agency. If the airlines want to turn you into a pretzel, the agency figures that’s their right so long as you can unwind fast enough to escape if something goes wrong.

When the FAA said safety – not seat size – was its priority, Flyers Rights took the agency to court.

The group said seat pitch – the distance between your seat and the one directly in front of you – has decreased from an average of 35 inches to 31 inches, and on some airlines it had been reduced to 28 inches. It said the width of a seat has shrunk from about 18.5 inches to 17 inches, even as the bottoms of many people have grown wider.

“Airlines will do almost anything to make a buck, I’m sorry to say,” said Brent D. Bowen, a dean at the Embry-Riddle Aeronautical University in Arizona, who for 28 years has put out the Airline Quality Rating.

“They’ve now gotten to the point where they automatically put you in the worst seats and you have to buy your way out,” Bowen said. “They now have five classes of service – even three classes of economy seats – and they have a strategy only to put you in the middle of a row in a tiny seat in the back of the aircraft.”

Bowen said the remedy for cramped seating has to come from the courts and Congress.

“There’s no alternative because the airlines are not going to set a reasonable standard,” Bowen said.

Rep. Steve Cohen, D-Tenn., has pushed an amendment through the House Transportation Committee that would require the FAA to set seat sizes.

“It’s clear that the FAA must review seat sizes and the distances between rows of seats,” Cohen said.