Article 123 was lost on 24 May 1963 during a low-altitude, subsonic flight to test an inertial navigation system.

With a faulty fuel gauge, CIA Pilot Walt Ray was on final to Groom Lake, NV, when the A-12 ran out of fuel. Walt Ray ejected from the aircraft, he failed to seperate from the ejection seat and was killed when he landed in seat.

The newly-installed SAS (Stability Augmentation System) had the yaw and pitch gyros wired backwards, causing the airplane to lose complete control just seconds after takeoff from Groom Dry Lake; 

While on a FCF (Functional Check Flight) CIA Pilot Jack Weeks and the A-12 disappered, No trace was ever found of pilot or aircraft.

The crash occurred on 9 July 1964 while Article 133 was approaching the runway after a Mach 3 check flight.

Some sources say Pt. Mugu, CA). While launching a D-21 drone, the drone was trapped in the shock wave of the aircraft, forcing the drone back into the M-21, causing the aircraft to break-up at Mach 3

On 25 January 1966, SR-71A (61-7952) was scheduled for a mission to test reconnaissance systems sensor performance and evaluate use of the navigation system as a controller for integrated sensor and aircraft management. The flight crew included Lockheed test pilot William A. Weaver and flight test reconnaissance and navigation systems specialist James T. Zwayer. The mission callsign was DUTCH 54.

On 18 December 1969, SR-71A (61-7953) was scheduled for a functional check flight (FCF), piloted by SR-71/F-12 Test Force director Col. Joe Rogers and his Reconnaissance Systems Operator (RSO), Maj. Gary Heidelbaugh. The mission callsign was DUTCH 68. The aircraft configuration included, for the first time ever, the Optical Bar Camera (OBC) nose assembly.