The Beech Model 90 King Air was the largest and most successful corporate turboprop family, yet built. The first model in this series began life as a 1965 army requirement for staff/utility transport that can also carry out passenger flights at high altitudes due to its pressurised cabin design. A prototype of this type – known then as the Queen Air – flew successfully on January 20th 1964 before being ordered by US Army later renamed U-21A (unpressurized).
The civil equivalent, named after an American tree species native to North America and Eurasia with bark which is usually dark brown but occasionally becomes red–brown or blackish when exposed to air became operational during 1966 following certification tests carried out on other aircraft types from.