A new report shows that only seven out of 10 of Air Force planes are in good enough condition to fly.

Official statistics say that three out of 10 aircraft in the Air Force fleet are not in commission because they are getting upgraded, undergoing maintenance, inspections, or heavy-duty repair work, the Air Force Times reports.

The problem also shows no sign of slowing down. The mission-capable rate, or the way the Air Force measures how much its fleet is ready to fight or fly other measures, has been showing a steady decrease.

Mission-capable rates for Air Force helicopters and airplanes were at nearly 74 percent in 2014. In 2015, the rate dropped to 73 percent, and in 2016 the rate dropped to 72 percent.

The reason for this decline in mission-ready aircraft is due to an aging Air Force fleet.

Air Force leaders have said that the Air Force’s aging fleet and decline in readiness rates have been a problem for years.

“Our highest investment priority is in improving readiness,” acting Air Force Secretary Lisa Disbrow said March 3 at the Air Force Association’s Air Warfare Symposium in Orlando, Florida. “The aircraft we have on the ramp are too old. We need to revitalize the fleet.”

The declining aircraft readiness rate can also be attributed to a shortage of experienced maintenance airmen to fix aircraft, although the Air Force wants to make its goal to eliminate that shortfall by the end of 2019.

While the Air Force is dealing with an aging fleet on Earth, they are also training airmen for the possibility of war waged in space, Military.com reported.