Rear Admiral Penniman graduated from the United States Naval Academy with the class of 1979 and was designated a naval aviator in September 1981.

Following an instructor pilot tour in the A-4 Skyhawk, Penniman reported to Fighter Squadron (VF) 124 for training in the F-14A Tomcat. He was subsequently assigned to VF-211 where he deployed twice aboard USS Kitty Hawk (CV 63). Following an instructor pilot tour with VF-124, he reported to VF-114 where he served as maintenance officer and deployed aboard USS Abraham Lincoln (CVN 72) in support of Operation Desert Storm. Penniman returned to VF-124 to serve as operations officer and executive officer. In the spring of 1993, he assisted in the establishment of Fighter Wing Pacific, and subsequently served as the wing's first operations officer.

Upon release from active duty in March 1994, Penniman held assignments as chief of staff for operations with Reserve units supporting Commander, Naval Air Forces, U.S. Pacific Fleet and Commander, U.S. 3rd Fleet. In October 2002, he assumed command of Naval Reserve Carrier Group 0194. Recalled to active duty in January 2003, Penniman was assigned to the Joint Forces Air Component commander's staff, U. S. Central Command, where he served as night director, Combat Plans Division during Operations Southern Watch and Iraqi Freedom. In October 2004, Penniman was reassigned to 3rd Fleet Joint Forces Air Component Commander 0194 and served as chief staff officer until assuming command of the unit a year later. He was subsequently assigned as chief staff officer with Commander United States Pacific Fleet Det. 420. Penniman's first flag assignment was as deputy commander, U.S. 3rd Fleet. He is currently serving as the Reserve deputy commander and chief of staff for U.S. Pacific Fleet.

During his career, Penniman accumulated in excess of 3,000 flight hours and 430 carrier-arrested landings. His military awards include the Legion of Merit (2 gold stars); Defense Meritorious Service Medal; Meritorious Service Medal (2); Air Medal; Navy and Marine Corps Commendation Medal (4), the Navy and Marine Corps Achievement Medal (2), and other unit, campaign and personal decorations.