Among the many products D regulates are lights that line airport runways and the metal bases in which those lights sit. Light bases used in runways must be very strong because they experience powerful forces--such as airplanes landing on them and snowplows driving over them--and must retain their original alignment to illuminate the runway properly. Also, because runways are repaved frequently, the height of the bases must be adjustable so they can remain flush with the runway's surface. D has long required all types of runway light bases to pass a torque test, which checks whether the base can withstand a strong force without rotating. In April 2005, D issued Advisory Circular 42D, which specified that torque testing would only be required for 'bases that utilize a method of height adjustment that is integral to the base or extension and are designed for field adjustment.' The test remained the same but only adjustable products, not fixed products, had to pass the torque test. Thirteen months later, D issued Advisory Circular 42E (AC-42E), which made the required torque test far more stringent. Two months after issuing AC-42E, D emailed a draft Advisory Circular 42F to a few companies that make or install runway light bases. P was not included in that email. The torque testing requirements in the draft circular, however, were identical to those in AC-42E; that is, the draft required freestanding torque tests for adjustable products but no torque test for fixed products. Olson Industries argued that adjustable products could never pass the freestanding torque test and that the circular was unfair because fixed products if subjected to the test, couldn't pass it either. The company also complained that the revised test was unjustified because it had never seen a problem with an installed adjustable product in its twenty years of experience. Siemens Airfield Solutions made exactly the same points. An agency employee prepared a response to these comments. This response was the only justification D has provided for its decision. D emailed the response to selected companies at approximately the same time the agency published the final version of AC-42F. D issued the final version of AC-42F on October 17, 2006, making no changes from the draft circular regarding the torque testing required for adjustable products used in runways. P filed a petition for review of AC-42F. P argues that D acted arbitrarily and capriciously by imposing a freestanding torque test on adjustable products but not fixed products. D claims that the court lacks jurisdiction and that it acted reasonably when it decided to treat the two products differently.