Learjet is a subsidiary of Bombardier Aerospace that manufactures small jet passenger aircraft. However, in a marked example of success in branding, the name has become synonymous with airplanes of this kind that it is used to describe all of them, and not just those made by Learjet. For the purposes of this description, there is the brand "Learjet," and the jet aircraft type usually described as a "Lear Jet."
When people say "Lear Jet," they usually mean what is described by the aerospace industry as a business or private jet. These are small, jet-powered passenger aircraft meant for civilian use, although the original Learjet was an adaptation of a Swiss ground attack airplane. Some jets that are marketed as "business jets" are in reality modified, cut-down jetliners sold for use in something other than commercial air traffic. The fluidity of the terms describing jets of this type does lead to some confusion.
As previously noted, most jets of this type have two engines. There have been some production models in the past that had three or even four engines. None have just one engine, for safety reasons. Having two engines allows for limited flight to continue in the event of a failure. These engines are almost always mounted on the rear of the fuselage, and not under the wings. Because Lear Jets are smaller and lower to the ground than jetliners, their engines cannot be slung under the wings.
A large number of companies manufacture small passenger jets. Bombardier/Learjet is arguably the most famous for this kind of aircraft. Others include Cessna, British Aerospace, Dassault, Eclipse Aviation. Embrear, Gulfstream and Hawker Beechcraft. Over one hundred Lear Jet type aircraft have been produced over the years, and several dozen remain in use today. Bombardier/Learjet alone has been involved in more than two dozen aircraft models, most of which are still flying today.
Despite the wide variety of jet models in service, the differences between them are often technical in nature and not readily visible to the untrained observer, as outwardly they mostly look the same: small aircraft with a pair of rearward mounted engines. A notable exception to this is the Dassault Falcon 50EX and 900, the sole example of a light triple-engined jet still in production today.
Lear Jets are used in a variety of roles. Companies and wealthy individuals buy and use them for personal transport. They are also used for express parcel delivery and chartered air taxi service. They have occasionally been used as air ambulances, and been retrofitted and pressed into military service. For example, the US Air Force uses the Learjet 35 as a light personnel transport, and in this role it is designated the C-21, while an Argentine Air Force Learjet 35 was being used as a reconnaissance plane in the 1982 Falklands War and was shot down by the Royal Navy.
