In South Korea an air force officer, Lee Chul-su, was recently promoted to colonel. What was special about this was that 14 years ago Lee was a captain in the North Korean Air Force. But he decided to defect, in his elderly MiG-19 fighter, flying out over the water, along the west coast, to a South Korean air base. Lee was allowed to join the South Korean Air Force, where he served as an expert, and instructor, on how the North Korean air force operated.
Very few North Korean pilots have defected like this. The only other one got out in 1983, also flying a MiG-19. This is no accident. The North Koreans take precautions to prevent this sort of thing. But other pilots have tried anyway. Last August a North Korean MiG-21 jet fighter crashed in China, 200 kilometers north of the border. The pilot did not eject and there was no fire after the plane plowed into the ground (indicating it was out of fuel.) China later reported that the aircraft went off course because of "mechanical problems." But that does not explain why the pilot did not try to land or bail out. A more likely explanation was that the pilot was trying to defect (to Russia, as China tends to return defectors). To avoid that possibility, North Korea warplanes are supplied with minimal fuel for training flights, and their ejection seats are disabled in peacetime. Other interceptors are kept in readiness to chase down and destroy defectors. So to get out, pilots have to evade all this scrutiny, and use your minimal fuel to get to someplace you will be safe. It isn't easy.
North Korean aircraft are much older than their South Korean counterparts, and their pilots get much less time in the air. North Korea air combat tactics do not emphasize initiative, anyway. Increasing economic problems in the last decade have further reduced fuel available for pilot training. Thus most North Korean pilots are trained to carry out surprise, and often suicidal, attacks early in any future war with South Korea.