On October 08th, 1947, An American Airlines DC-4 was in flight over El Paso, Texas, when, as a prank, a captain riding in the jump seat engaged the gust lock in flight.
Not knowing the gust lock had been engaged, the command pilot rolled the elevator trim tab with no response. When the jump seat captain disengaged the gust lock, the aircraft went into a steep dive, executed part of an outside roll and became inverted.
Neither the command nor jump seat captain had seat belts on and they accidentally feathered No. 1, 2 and 4 engines when they hit the controls with their heads. No one realized it at the time but the feathering reduced power and allowed the co-pilot, who was strapped in, to pull out of the dive only 350 feet from the ground.
