A Viet Nam story: One of our squadron instructors was up with a new pilot for an orientation tour in a Cessna Skymaster 337 (O-2A). Right after a stall series and close to Cam Rahn Bay, the elevator cable snapped. Both yokes were just flopping back and forth regarding pitch control. Our instructor decided he had seen enough. He jettisoned the right door and was standing in the door frame about ready to jump with his backpack parachute when the other pilot pulled him back in. The new pilot had figured out that the electric trim still controlled the pitch. They made a very long, safe straight-in approach.