The U.S. Air Force is disbanding it's force of C-9 aeromedical evacuation aircraft (military versions of the DC-9). One reason is that the aircraft are over three decades old. But the main reason is that these aircraft don't have much to do anymore. Most of the C-9s work in peacetime has been moving military (and their dependents) patients from one military hospital to another. But in the early 1990s, the Department of Defense introduced it's own HMO (TRICARE), which made local hospitals and doctors available for dependents and military retirees. This has cut the work for C-9s from 70,000 patients moved in 1990 to about 11,000 in 2001 and, it is expected, about 3,000 in 2005. At the same time, it was found more convenient to move these patients on other available military aircraft (C-130s and KC-135s). Increasingly, it became a no-brainer to retire the C-9. The last one was taken out of service last month.