A new phase of testing in the F-35 Lightning II program began with the arrival of the first two operational test aircraft March 6, 2013, at Edwards Air Force Base, Calif. Team members from the 53rd Wing's 31st Test and Evaluation Squadron, a tenant unit here, will determine how to best tactically operate the F-35A conventional takeoff and landing variant of the fifth-generation fighter. (U.S. Air Force photo/Laura Mowry)