United Airlines has closed the sale of a 1997-vintage Boeing 747-400 (MSN 28715) aircraft, equipped with PW4056 engines, to Scaled Composites.
The 747-400 will be used to build the world's largest aircraft to serve as a mobile platform for low-cost satellite launches.
The transaction was arranged by remarketing agent, Bristol Associates.
The project was conceived by aerospace designer Burt Rutan and it is funded by a closely held venture of Microsoft founder, Paul Allen.
According to Flightglobal's Ascend Online database, United operates 27 747-400s. The eldest vintage is 1989 while the youngest aircraft were built in 2000.