An appeals court panel said Friday that federal officials must reconsider their decision not to regulate the size of airline seats as a safety issue.

One of the judges called it “the Case of the Incredible Shrinking Airline Seat.”

The Flyers Rights passenger group challenged the Federal Aviation Administration in court after the agency rejected its request to write rules governing seat size and the distance between rows of seats.

On Friday, a three-judge panel for the federal appeals court in Washington said the FAA had relied on outdated or irrelevant tests and studies before deciding that seat spacing was a matter of comfort, not safety.

The judges sent the issue back to the FAA. They said the agency must come up with a better-reasoned response to the group’s safety concerns.

“We applaud the court’s decision, and the path to larger seats has suddenly become a bit wider,” said Kendall Creighton, a spokeswoman for Flyers Rights.

The passenger group says small seats that are bunched too close together slow down emergency evacuations and raise the danger of travelers developing vein clots.

FAA spokesman Ian Gregor said the agency was considering the ruling and its next steps. He said the FAA considers the spacing between seat rows when testing to make sure that airliners can be evacuated safely.

The airline industry has long opposed the regulation of seat size. Its main U.S. trade group, Airlines for America, declined to comment on the ruling.