[mars]

Actually how this happened was very simple, that Soviet pilot was a fighter pilot with several air combat victories in his credit, he was shot down and taken prisoner, in the chaos of the POW camp, he managed to took a dead fellow prisoner's identidy, so Germans did not know he could fly aircraft.
That day he was among one of ten labor details, and he found there was a He-111 parked in the airport without guard, they made a quick decision on the spot, took a turn, board the aircraft, and before Germans found anything was wrong, they took off and flew away.