February 29, 1964

1964: President Lyndon B. Johnson acknowledged the existence of Lockheed’s A-11 (YF-12A), which could fly 2,000 MPH (Mach 3) above 70,000 feet. The YF-12 then entered testing at Edwards AFB to determine its suitability as a long-range interceptor. The Central Intelligence Agency ordered it in 1960 as a single-seat reconnaissance plane (A-12), and the USAF later produced it as the SR-71.
The main changes involved modifying the A-12’s nose by cutting back the chines to accommodate the huge Hughes AN/ASG-18 fire-control radar originally developed for the XF-108 with two infrared search and track sensors embedded in the chine leading edge, and the addition of the second cockpit for a crew member to operate the fire control radar for the air-to-air missile system.