Likely it was flown not by a professional pilot but by a civilian with some basic training in crop dusting. The reason is simple - it’s impossible for a professional to mistake flying to China (South) and flying to Russia (North.) You could do that by stars, by the sun, and of course by any compass. Pilots who fly these airplanes on duty know the land, can find the compass among the instruments, and can escape easily. Only a civilian can be confused enough to lose orientation and on top of that probably make a small mistake in piloting that an old military aircraft (without computers) is not likely to forgive.
The map picture shows him headed almost due north. He was flying from the southern and westernnmost point on the border.