7,500 Hours: Longest Flying A-10 Pilot Ever Retires After 37-Year Career Sept. 5, 2024 | By David Roza An era came to a close late last month when the highest-time A-10 pilot, Lt. Col. John ‘Karl’ Marks, retired after a 37-year career and 7,500 hours behind the stick of the Thunderbolt II, affectionately known as the Warthog.