 "Flagstaff" and "Tucumcari" were too mechanically complex for the repair facilities in Vietnam, and as a result were ultimately withdrawn from combat.Upon her return to the U.S. in 1970, she was assigned to the Amphibious Forces of the Pacific Fleet where she participated in numerous readiness trials and training exercises and was also used as a test-bed for various craft subsystems, such as the Navy's Advanced Hydrofoil Development Program.Flagstaff Plank owner.