Aircraft charter brokers have entered the marketplace through the ease of setting up a website and business online. Aircraft charter operators are legally responsible for the safe operation of aircraft and charter brokers require no economic authority and are largely unregulated. The Department of Transportation requires that air charter brokers disclose to the consumer that they do not operate aircraft and cannot use terms like "our fleet of aircraft", "we operate", "our charter service" and others.
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.