Mission essential – Robert Rudder, Dan Mel, security forces specialists Published Feb. 21, 2013 VANCE AIR FORCE BASE, Okla. -- Airmen 1st Class Robert Rudder and Dan Mel are members of the 71st Security Forces Squadron at Vance Air Force Base. Security Forces personnel are the first line of defense and the maintainers of the rule of law on Air Force bases and installations. Each day Vance Security Forces safeguard the men, women, aircraft and infrastructure that make training world-class pilots possible - the very definition of mission essential.