Some airports have begun mounting a legal challenge to federal regulators' decision to shut down 149 contractor-operated air traffic control towers, citing safety requirements.

The Tucson Airport Authority is still weighing its options, an official said Friday.

"We are in the process of reviewing all available options that would keep the tower open, but have not made any decisions," Airport Authority spokeswoman Katy Smith said.

The air-traffic control tower at Ryan Airfield is scheduled to close April 7, as part of a plan to close 149 contractor-operated towers to deal with automatic federal budget cuts.

The Federal Aviation Administration has notified the Tucson Airport Authority that the Ryan tower is among the first round of 24 tower closures. The airfield will remain open despite any tower closure.

Another 46 towers will close on April 21, and the remaining 79 will shut down on May 5, under the FAA’s plan to implement the so-called sequestration cuts.

Critics including local aviation officials say the tower closures jeopardize air safety. Without air-traffic control, pilots must coordinate landings and takeoffs themselves via radio.

The Central Illinois Regional Airport, Spokane International Airport in Spokane, Wash., and three airports in Florida have filed suit against the FAA in the U.S. Circuit Court of Appeals in Washington, D.C., The Associated Press reported. The court has combined the suits into a single case.

The airports are arguing that the agency has violated a federal law meant to ensure major changes at airports do not erode safety.

FAA spokeswoman Laura Brown said the agency can’t comment on pending litigation.