Short for Jet-Bomber Operations Special School, J-BOSS is the Alliance Liberator Air Force's premier flight school and top flight operations training program. It shares many similarities with the NO MERCY school operated by the Crimson Blade, and was indeed modeled on their program.
ALAF operates a significantly smaller variety of aircraft than the Crimson Blade, so their program is much more limited. As such, the training covers both single-seat jet-aircraft roles (filled by the Doer-Daisy) as well as multi-engine high-altitude bombers, and close air-support vehicles.
While Alliance military forces are generally considered inferior, it's been pointed out that because J-BOSS covers a wider variety of roles, a graduate could be considered a much more versatile pilot. NO MERCY, for example, is a strike-fighter weapons training program; it includes only fighter-aircraft and focuses on ground attack and air-to-air combat roles. By contrast, J-BOSS trains its graduates in ground attack, air-to-air, and air-to-ground assaults, air-interceptor techniques, bomber escort, bomber piloting, and even advanced helicopter piloting (the Alliance's preferred close-air support vehicle). J-BOSS also graduates significantly more pilots and has a lower standard for admission.