The A-10 is a heavily armed and armored attack plane with a long loiter time—and the GAU-8 Avenger 30-millimeter gatling gun that holds 1,350 armor-piercing rounds and is significantly more useful than a stealthy, fast, software-laden fighter like the F-35 for close air support.
To keep the A-10 fleet of 283 aircraft flying, Hill Air Force Base in Utah, where most of the A-10 maintenance and repair work is done, is continuing to prepare for increased capacity. According to Aviation Week, the A-10 division at Hill has improved the aircraft availability rate from about 63 to 68 percent in the past year, accounting for 87,000 flight hours worldwide in fiscal year 2015.
The Air Force has been pressured by a group in Congress with widespread public support to keep the A-10 fleet maintained and flying CAS missions until an adequate replacement has been realized.
SOURCES- Popular Mechanics, Aviation Week