Before becoming an astronaut, Armstrong was in the United States Navy and served in the Korean War. After the war, he served as a test pilot at the National Advisory Committee for Aeronautics (NACA) High-Speed Flight Station, now known as the Dryden Flight Research Center, where he flew over 900 flights in a variety of aircraft. As a research pilot, Armstrong served as project pilot on the F-100 Super Sabre A and C variants, F-101 Voodoo, and the Lockheed F-104A Starfighter. He also flew the Bell X-1B, Bell X-5, North American X-15, F-105 Thunderchief, F-106 Delta Dart, B-47 Stratojet, KC-135 Stratotanker, and was one of eight elite pilots involved in the paraglider research vehicle program (Paresev). He graduated from Purdue University and the University of Southern California.
Neil is survived by his second wife, Carol Held Knight, whom he married in 1992.