Boeing's KC-46 aerial refueling aircraft completed all required Supplemental Type Certificate (STC) flight tests following a successful refueling/communications flight with a C-17 Globemaster III. 

The STC is one of two required FAA airworthiness certifications. Boeing previously received its Amended Type Certificate from the FAA for its core 767-2C configuration in December 2017. As part of STC testing, the combined Boeing/Air Force team had to validate both the boom and drogue systems for aerial refueling with multiple receiver aircraft. They also demonstrated the KC-46 can take on fuel from KC-135, KC-10 and other KC-46 tankers, conducted night and day lighting tests and tested the aircraft defensive systems and avionics. 

Boeing is currently under contract for the first 34 of an expected 179 tankers for the US Air Force.