The aircraft, known as ZM137, departed at 10:16 a.m. with Lockheed Martin F-35 Chief Test Pilot Alan Norman at the controls. ZM137 will complete a series of company and government checkout flights prior to its acceptance by the U.K. Ministry of Defence. ZM137 will join U.K. aircraft ZM135 and ZM136 at Eglin Air Force Base, Fla., later this year where it will be used for pilot and maintainer training.