If you boarded a passenger plane in 1950 and peeked into the cockpit, you would have seen five people in there (almost certainly men): two pilots, a radio operator, a navigator and a flight engineer.
원문출처 : https://www.cnn.com/travel/article/single-pilot-planes/index.html
원문출처 : https://www.cnn.com/travel/article/single-pilot-planes/index.html