Pilots Asphyxiated

Mount Carmel, Pennsylvania, June 17, 1948, a United Airlines Douglas DC-6 aircraft encountered an in-flight fire in the cargo hold while on a flight from Chicago to New York. The Pilots responded to the fire warning by discharging carbon dioxide extinguishers into the cargo hold followed by the pilots lowering the nose for an emergency decent.

As a result of the lowering the aircraft nose, the carbon dioxide, being heavier than air accumulated in the cockpit and asphyxiated the crew. The aircraft crashed into high voltage lines killing all 43 on board.