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.

A three-judge panel for the federal appeals court in Washington said the FAA had relied on outdated or irrelevant tests and studies before deciding that seat spacing was a matter of comfort, not safety.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 and said the agency must come up with a better-reasoned response to the group’s safety concerns.