Service Ceiling 90,000 feet....pretty well takes the cake I believe.
Air Force testing
YF-12A
During flight tests the YF-12As set a speed record of 2,070.101 mph (3,331.505 km/h) and altitude record of 80,257.86 ft (24,462.6 m), both on 1 May 1965,[9] and demonstrated promising results with their unique weapon system. Six successful firings of the AIM-47 missiles were completed. The last one launched from the YF-12 at Mach 3.2 at an altitude of 74,000 ft (22,677 m) to a JQB-47E target drone 500 ft (152 m) off the ground.[13] One of the Air Force test pilots, Jim Irwin would go on to become a NASA astronaut and walk on the Moon.
The program was abandoned following the cancellation of the production F-12B, but the YF-12s continued flying for many years with the USAF and with NASA as research aircraft.
