The U.S. Air Force’s Presidential and Executive Airlift Directorate is planning on executive sonic transports to be used as Air Force One. The current Air Force One, VC-25A is a modified version of a Boeing 747-200B. The Boeing 747-8i (VC-25B) is set to replace the VC-25 A, which is under development. Boom Supersonic, Exosonic and Hermeus have been handed separate contracts by the Directorate for development of supersonic aircraft. “Transporting key decision makers and teams around the world in half the time can be the difference between success and failure,” said Brigadier General Ryan Britton, Program Executive Officer for Presidential & Executive Airlift Directorate. The last commercial supersonic flight took place on October 24, 2003. Overture by Boom Supersonic offers the USAF passenger capacity, speed, and space for necessary mission systems. Overture's maiden flight is planned in 2025. Exosonic is developing a low boom aircraft by utilising boom softening techniques while Hermeus has proposed to build a Mach 5 hypersonic aircraft. In February 2020, Hermeus successfully tested a Mach 5 engine prototype.