USA-299, also referred to as USSF-7 and Orbital Test Vehicle 6 (OTV-6), is the third flight of the first Boeing X-37B, an American unmanned vertical-takeoff, horizontal-landing spaceplane. It was launched to low Earth orbit aboard an Atlas V launch vehicle from SLC-41 on 17 May 2020. Its mission designation is part of the USA series.

Atlas V is an expendable launch system and the fifth major version in the Atlas launch vehicle family. It was originally designed by Lockheed Martin, now being operated by United Launch Alliance (ULA), a joint venture between Lockheed Martin and Boeing. It is used for DoD, NASA, and Commercial payloads. It is America's longest-serving active rocket. After 87 launches, in August 2021 ULA announced that Atlas V would be retired, and all 29 remaining launches had been sold. As of January 2024, 17 launches remain. Other future ULA launches will use the new Vulcan Centaur rocket.