Command pilot Neil A. Armstrong and pilot David R. Scott achieved a historic milestone on the afternoon of March 16, 1966: the first docking of two spacecraft in Earth orbit. The Agena target vehicle had launched at 10:00 a.m. EST; Gemini VIII followed 101 minutes later. After a flawless rendezvous, Armstrong guided the nose of Gemini into the Agena's docking collar on the fifth revolution. The triumph lasted twenty-seven minutes. Suddenly the combined vehicle began to yaw and tumble. Believing the Agena was at fault, Scott undocked—only to find Gemini VIII spinning even more violently, approaching one revolution per second. The problem was a stuck OAMS roll thruster, short-circuited and firing continuously. Out of radio contact with Houston, Armstrong made a critical decision: he shut down the entire OAMS and activated the Reentry Control System (RCS) thrusters on the spacecraft's nose. Using nearly 75 percent of his precious RCS fuel, Armstrong stopped the spin. Mission rules required an immediate return once the RCS was fired for such an emergency. The crew landed in the western Pacific, 620 miles south of Yokosuka, Japan, after only 10 hours and 41 minutes in space. Scott's planned spacewalk was cancelled, but the docking itself was proven. Armstrong's cool systems knowledge under extreme duress—honed during his years as an X-15 pilot—would serve him again three years later when he guided Apollo 11 to the lunar surface.