Upon returning to the runway, it was discovered that some of the A-12’s equipment was installed backward.
On April 26, 1962, the classified A-12 “Oxcart” conducted its inaugural flight at a nonexistent airfield in Nevada. The aircraft, referred to as “Article 121,” began to experience severe oscillations in the air and vanished into a cloud of dust, which Clarence “Kelly” Johnson, the plane’s designer, described as “horrible to watch.” According to the Strategic Air Command & Aerospace Museum’s Facebook page, after landing, it was found that some of the A-12’s components had been installed backward. This mistake was fixed, and later flights went smoothly.
The classified CIA plane, designed to succeed the U-2, can reach speeds of Mach 3 (exceeding 2,000 miles per hour) at heights surpassing 80,000 feet.
The A-12 Oxcart was a highly classified, single-seat reconnaissance aircraft, making it more secret and significantly rarer than the SR-71. The SR-71 was originally developed from the A-12.
Even though it was intended to succeed the U-2 spy plane, both this aircraft and the SR-71 were retired before the U-2, which is still operational today.
As stated by Lockheed, the A-12 Oxcart had a confirmed operational altitude of 95,000 feet and could reach speeds of 2,221 mph, equivalent to Mach 3.35. In comparison, the SR-71 had a maximum altitude of 85,000 feet and could fly at 2,112 mph, or Mach 3.2. However, anecdotal accounts are suggesting that both aircraft may have exceeded their officially recorded speed and altitude capabilities.
The CIA operated the A-12 at slightly less than its full potential, as their official numbers are marginally lower than those provided by Lockheed: roughly 3 mph slower and 5,000 feet lower.
The following is a spec-sheet from the CIA’s official website.’

The two aircraft can be seen next to each other in Blackbird Park, located within Air Force Plant 42 adjacent to Palmdale Regional Airport in Palmdale, California.

Photo by Lockheed Martin, U.S. Air Force, and CIA