In a wet lease arrangement, the financing entity, or lessor, provides the aircraft, and complete crew, maintenance and insurance (ACMI) to another party at a cost based on hours of operation over a set time period. The lessee pays for fuel, airport fees, duties, taxes and other operational costs. Wet leases generally are established for one to 24 months. (Any shorter period would be considered simply ad hoc charter, which can be thought of as wet lease by the hour or mission.) In the commercial airline world, wet leases are typically utilized to provide supplemental lift during peak traffic seasons or during annual heavy maintenance checks. In the United Kingdom, a wet lease is employed whenever an aircraft is operated under the air operator's certificate (AOC) of the lessor.
Though the early Lockheed Jetstar had four, most production business jets have two jet engines, mostly rear-mounted podded engine. If mounted below their low wing, it wouldn't allow sufficient engine clearance without a too long landing gear. The HondaJet is the exception with its over the wing engine pods. Dassault Falcon still builds three-engine models derived from the Falcon 50, and the very light jet market has seen several single-engine design concepts and the introduction of the Cirrus Vision SF50 in 2016.