A federal appeals court didn't give much legroom to the Federal Aviation Administration in a decision Friday related to the size of airline seats.

The U.S. Court of Appeals for the D.C. Circuit ruled the FAA did not provide enough information on why it denied a nonprofit airline consumer group's request to regulate the size of airline seats. In what Judge Patricia Millett called “the Case of the Incredible Shrinking Airline Seat,” the court said the FAA didn't show it adequately considered airline seats are shrinking while passengers are growing in size, nor the possible effects the phenomenon has on emergency evacuations.

“In short, when an agency denies a petition for rulemaking, the record can be slim, but it cannot be vacuous,” Millett wrote. “Especially so when, as here, the petition identifies an important issue that falls smack-dab within the agency's regulatory ambit. While we do not require much of the agency at this juncture, we do require something.”