De Northrop T-38 Talon is a two-seat, twin-engined supersonic jet trainer. It was the world’s first supersonic trainer and is also the most produced. The T-38 remains in service as of 2017 in several air forces.
The United States Air Force (USAF) operates the most T-38s. In addition to training USAF pilots, the T-38 is used by NASA. The U.S. Naval Test Pilot School is the principal US Navy operator (other T-38s were previously used as USN aggressor aircraft until replaced by the similar Northrop F-5 Tiger II). Pilots of other NATO nations fly the T-38 in joint training programs with USAF pilots.
As of 2015, the T-38 has been in service for over 50 years with its original operator, the United States Air Force.
Bron: Northrop T-38 Talon op Wiki