At the age of sixteen, Greenwood entertained crowds with exhibition parachute jumps for local air shows. He then put his experience as a parachute rigger to use in the United States Navy. In the early 1950’s the Civil Aeronautics Administration issued new criteria for airshows based upon Greenwood’s recommendations. In 1955, Greenwood joined Beech Aircraft Company as manager of press relations. He later became the director of public affairs for the Federal Aviation Administration in Washington, D.C., from 1970 to 1973. Jim returned to Wichita in 1974 as vice-president of Gates Learjet, where he organized ta record-setting flight around the world for golfer Arnold Palmer and astronaut Neil Armstrong.