Aircrews from the U.S. Air Force and Boeing completed the first KC-46A Pegasus tanker refueling mission 20,000 feet above Washington state.

During the flight, which lasted nearly six hours, the tanker aircraft was used to refuel an F-16 fighter aircraft. The test team was able to offload 1,600 pounds of fuel from the Pegasus into the F-16. KC-46 system program manager Col. Christopher Coombs says the flight officially kicked off the Milestone C aerial refueling demonstration, a prerequisite for low-rate initial production.

"We have a lot of work yet to do, but this is an exciting time for the airmen who are preparing to fly, maintain and support the KC-46 Pegasus for decades to come," Coombs said in a statement.

The flight test, which involved multiple contacts between the Pegasus and the F-16, was performed to verify the tanker's ability to transfer fuel. The aircraft flew with its 56-foot boom downward toward the F-16, and waited for the fighter to move into position before fully extending the boom down to the F-16's refueling receptacle. The system automatically turned off the pumps once the transfer was complete.

The KC-46A is scheduled to perform more flight refueling tests with additional military aircraft, including the C-17, F/A-18, A-10, and the AV-8B. The tanker has completed 32 flights since it first took flight in September 2015.

The Boeing-made Pegasus aircraft is designed for refueling all U.S. and allied military aircraft, and is also equipped with protection technology to detect, avoid, defeat and survive threats during its missions.