The Navy’s unmanned fighter completed its first aerial refueling Wednesday, the first of the aircraft’s final tests before it’s retired to make way for the next generation of carrier-launched drones.

The X-47B received over 4,000 lbs. of fuel from an Omega K-707 tanker aircraft, Naval Air Systems Command said, while flying off the coast of Maryland and Virginia from Naval Air Station Patuxent River, Maryland.

It was a huge achievement for unmanned aviation, according to the unmanned carrier aviation program manager.

“The ability to autonomously transfer and receive fuel in flight will increase the range and flexibility of future unmanned aircraft platforms, ultimately extending carrier power projection,” Capt. Beau Duarte said in a news release.

The aircraft flies preset programs within its software, so an operator pushes a button to initiate the refueling process.

The refueling is the last in a series of tests the X-47B has carried out in recent years, including landings and takeoffs aboard an underway carrier and flying in the pattern with manned jets.

Once the refueling tests are complete, the UAV will be sent to a museum or the Navy’s aircraft boneyard.

A follow-on aircraft, the Unmanned Carrier Launched Airborne Surveillance and Strike system, is scheduled for operability in the early 2020s.