High Quality Content by WIKIPEDIA articles! High Quality Content by WIKIPEDIA articles! The YC-14 was Boeing's entrant into the USAF's Advanced Medium STOL Transport (AMST) competition, which aimed to replace the C-130 Hercules as the USAF's standard STOL tactical transport. Although both the YC-14 and the competing McDonnell Douglas YC-15 were successful, neither aircraft entered production, and the AMST project was eventually shut down in 1979.