Search crews discovered the wreckage of a F-16 and the parachute of the missing pilot Saturday that crashed during a training exercise.
The wreckage is in a remote area in rugged terrain of western Arizona and is only accessible by helicopter while the status of the pilot is still unknown.
The pilot is unlikely to have survived, an Air Force source told FOX News. Some of the pilot's gear was found about 150 feet from the impact crater, said Mary Jo May, a base spokeswoman.
A definitive cause of the crash and the condition of the pilot still aren't available. The pilot was the only person on board, authorities said. The identity of the pilot, who was part of the 62nd Fighter Squadron, has not been released.
The crash occurred at about noon Friday south of Alamo Lake, Ariz., during a student training mission out of Luke Air Force Base.
The base in the world's largest F-16 training base, with about 185 F-16s.
Two other jets crashed in the last two years. In 2006, a pilot ejected safely from an F-16 and another pilot survived after a two-seat F-16 crashed during a training mission nearly nine months later. A 25-year-old pilot died in 2004 after his F-16 crashed.
FOX News' Jennifer Griffin and The Associated Press contributed to this report.