The Beech Model 90 King Air is a type of corporate turboprop twin. The first model in the largest and most successful family yet built, it began life as a US Army requirement for staff/utility transport with an unpressurized Queen Air prototype to meet that need; however, pressurization was added when this aircraft became available commercially as well.

The production civil equivalent-the Model 90 King Air -introduced significant improvements such as increased power (from PT6), improved reliability due to better design features like blade tip clearances on propeller blades