Armstrong was assigned to Fleet Aircraft Service Squadron7 (FASRON 7) at NAS San Diego (now known as NAS North Island). On November 27, 1950, he was assigned to VF-51, an all-jet squadron, becoming its youngest officer, and made his first flight in a jet, a Grumman F9F Panther, on January 5, 1951. He was promoted to ensign on June 5, 1951, and made his first jet carrier landing on two days later. On June 28, 1951, "Essex" had set sail for Korea, with VF-51 aboard to act as ground-attack aircraft. VF-51 flew ahead to Naval Air Station Barbers Point in Hawaii, where it conducted fighter-bomber training before rejoining the ship at the end of July.