The premise of the cartoon is that Jimbo was originally intended to be a Jumbo Jet, but his designer could not tell the difference between inches and centimetres, resulting in his diminutive size.
The television series features various talking airport-type ground vehicles: Tommy Tow-Truck, Claude Catering, Amanda Baggage, Phil the Fuel Truck, Sammy Steps and Harry Helicopter. Other plane characters appear from time to time, such as Old Timer, a Vickers Wellington bomber who gets into the story while flying to or from an airshow. The story is based at a fictional "London Airport", under the command of an irate controller who frequently ends episodes screaming "I want words with you, Jimbo!".