On July 4, 1989, Soviet MiG-23 pilot Nikolai Skuridin was on a routine training flight near Kolobrzeg, Poland, when his afterburner failed. Skuridin ejected, thinking the engine was completely dead, but the plane recovered and proceeded on autopilot into the west.
It must have had a lot of fuel, because it crossed out of Poland into East Germany, then into West Germany, then into the Netherlands, where a startled American air base sent up two F-15s to keep it company. As the MiG passed into Belgium the F-15s were told to shoot it down when it reached the North Sea, but it finally ran out of fuel near the French border, crashing into a house and killing a teenager.
The whole trip had covered 560 miles. Belgian Foreign Minister Mark Eyskens complained that the Soviets had issued no warning and no indication as to whether the pilotless plane was carrying dangerous weapons; it turned out that it was unarmed but carrying ammunition for a 23mm machine gun.
See Never Mind.