The C-9A Nightingale is the only aircraft in the USAF inventory specifically designed for the movement of litter and ambulatory patients.  It serves not only the military, but the Department of Veterans Affairs and civilian hospitals throughout the world.
     Experience gained in the early stages of American involvement in the Vietnam War highlighted the need for a medium-range aero-medical transport, and as a relatively low-cost expedient, an initial order for eight 'off-the-shelf' commercial McDonnell Douglas DC-9 Series 30 airliners was placed to be set aside for military conversion. Modifications included the provision of a special-care compartment, galleys and toilets fore and aft, and the addition of a third access door with a built-in hydraulic ramp to facilitate the loading of litters.  Accommodation was provided for up to 40 litters and 40 ambulatory patients, two nurses and three aero-medical attendants.
    The first C-9A was rolled out on 17 June 1968 and delivered to Scott AFB two months later; subsequent aircraft served with the 375th Aeromedical Airlift Wing of MAC (now 375th AW of AMC), and later with the 55th AAS of the 435th Tactical Airlift Wing (now 86th AW at Ramstein). Later orders brought the total deliveries to 21, in addition to three C-9C executive transports flown by the 89th Military Airlift Wing at Andrews AFB, MD. In addition to these operators, the C-9 is flown by the 374th AW at Yokota, while the 73rd AAS is an Air Force Reserve Associate unit at Scott, supplying aircrews to augment the active-duty crews.