The T-1A Jayhawk is a medium-range, twin-engine jet trainer used in the advanced phase of specialized undergraduate pilot training for students selected to fly airlift or tanker aircraft. It is also used to support navigator training for the U.S. Air Force, Navy, Marine Corps and international services.  The swept-wing T-1A is a military version of the Beech 400A. It has cockpit seating for an instructor and two students and is powered by twin turbofan engines capable of an operating speed of Mach .78. The T-1A differs from its commercial counterpart with structural enhancements that provide for increased bird strike resistance and an additional fuselage fuel tank.  The first T-1A was delivered to Reese Air Force Base, Texas, in January 1992, and student training began in 1993.   Since the late 1950s, Air Force undergraduate pilot training students have trained in two aircraft: the T-37 Tweet, the primary trainer, and the T-38 Talon, the advanced trainer. With the introduction of specialized undergraduate pilot training in 1993, students continue to receive their primary flying training in the T-37, but the advanced phase was tailored for students' follow-on assignments.  Advanced training for students identified to go into airlift or tanker aircraft is conducted in the T-1A. Those selected for bombers and fighters receive their advanced in the T-38. The T-1A is used at Columbus AFB, Miss., Laughlin AFB, Texas, and Vance AFB, Okla. It is also used at Randolph AFB, Texas, to train instructor pilots and at Naval Air Station Pensacola, Fla., for navigation training.