San Diego Air Sports (SDAS) Center operates a sports parachuting business in Otay Mesa, California. SDAS offers training to beginning parachutists and facilitates recreational jumping for experienced parachutists. It indicates that the majority of SDAS jumps occur at altitudes in excess of 5,800 feet. The jump zone used by SDAS overlaps the San Diego Traffic Control Area (TCA). Although the aircraft carrying the parachutists normally operate outside the TCA, the parachutists themselves are dropped through it. Thus, the air traffic controllers must approve each jump. In July 1987, an air traffic controller in San Diego filed an Unsatisfactory Condition Report with the Federal Aviation Administration (FAA), complaining of the strain that parachuting was putting on the controllers and raising safety concerns. The report led to a staff study of parachute jumping within the San Diego TCA. This was followed by a letter in March 1988 from the FAA to SDAS, informing SDAS that "[e]ffective immediately parachute jumping within or into the San Diego TCA in the Otay Reservoir Jump Zone will not be authorized." The FAA stated that the letter was final and appealable. SDAS challenged the letter in federal court on grounds that it constituted rulemaking without compliance with required Administrative Procedure Act (APA) procedures. Who is correct in this dispute and why? [San Diego Air Sports Center, Inc. v. FAA, 887 F.2d 966 (9th Cir.)]