The Canadian transcontinental and Montreal-New York routes were enhanced with the introduction of the DC-9's in April 1966. Since that time there have been modifications to existing aircraft, and the introduction of new technologically updated DC-9 models, so that they are still valuable contributors to the North American and Southern routes of Air Canada.
The most distinctive feature of the DC-9 is the high-level horizontal stabilizer mounted at the top of the rudder assembly to accommodate the installation of the Pratt & Whitney turbofan engines on either side of the aft fuselage.