The U.S. Air Force has changed the time overseas for its units from 90 days to 120. Unless there is a major conflict, this means that units spend four months overseas every two years. This also means fewer units going and coming, which saves time. Most air force personnel ship out with an air expeditionary forces (AEF), which is a miniature air force comprising fighter, bombers and support aircraft. Each of the ten AEFs have about 170 aircraft and 10-15,000 personnel. However, a lot of other air force troops, in high demand job categories (electronic warfare, AWACs, gunship crews) routinely find themselves going overseas for six months at a time.