[2] Sullivan, known to his friends and family as "Denny", graduated from the United States Naval Academy in 1950 and was commissioned an officer in the Air Force.
It was with this special extra-curricular USAF assignment that Sullivan was trained to fly surveillance missions for the CIA Central Intelligence Agency, in Project Oxcart, in Lockheed ADC "Skunkworks" program's advanced "spy plane" the Mach 3 (3 times the speed of sound) A-12 (forerunner design of the second generation SR-71).
Notably, the A-12 was a single seater aircraft, where the driver did both piloting and the equally demanding camera intelligence gathering duties.
He flew several mission flights over Vietnam in Operation Blackshield, surviving multiple SAM missile attacks on his plane where he cruised at altitudes in excess of 82,000 feet.
He was responsible for monitoring and providing staff support to pilot, navigator, and survival training programs at 11 bases and several detachments in this position.