High Quality Content by WIKIPEDIA articles! The McDonnell Douglas YC-15 was a four-engine short take-off and landing (STOL) tactical transport. It was McDonnell Douglas` entrant into the United States Air Force`s Advanced Medium STOL Transport (AMST) competition to replace the Lockheed C-130 Hercules as the USAF`s standard STOL tactical transport. In the end, neither the YC-15 nor the Boeing YC-14 was ordered into production, although the YC-15`s basic design would be used to form the successful C-17 Globemaster III.