After 55 years in flight, the US Air Force is planning to keep its biggest plane in action for a few more decades

• Since 1970, the US Air Force's C-5 cargo planes have carried troops and gear all over the world.
• The C-5 is the Air Force's biggest plane, and the latest model can haul 281,000 pounds and fly 518 mph.
• Thanks to recent upgrades, the Air Force now plans to keep its C-5s in service until at least 2040.

In March, the US Air Force announced that it had successfully incorporated 3D-printed parts into one of its C-5M Super Galaxy strategic transport planes.