Lt. Col. Chastain is the son of Clarice and Richard Smith of Jacksonville and Jim and Brenda Chastain in Oklahoma City. He is married to Susan Denkins Chastain, the daughter of Joyce and Lamar Denkins of Jacksonville. They have two sons, Hayden, 18, and Caleb, 15.
Lt. Col. Chastain has deployed in support of Operations Desert Shield, Desert Storm, Noble Eagle, Joint Force, Iraqi Freedom, Enduring Freedom and New Dawn. He had two recent deployments to Kabul International Airport, Afghanistan as Detachment Commander, and to Al Udeid Air Base, Qatar as Chief, Airspace Normalization, Air Forces Central.