The Bombardier Dash 8 or Q-Series, previously known as the de Havilland Canada Dash 8 or DHC-8, is a series of twin-engined, medium range, turboprop airliners. Introduced by de Havilland Canada (DHC) in 1984, they are now produced by Bombardier Aerospace. Over 1,000 Dash 8s of all models have been built,^[3] with Bombardier forecasting a total production run of 1,192 aircraft of all variants through to 2016.^[4]

The Dash 8 was developed from the de Havilland Canada Dash 7, which featured extreme short take-off and landing (STOL) performance. With the Dash 8, DHC focused on improving cruise performance and lowering operational costs. The engine chosen was the Pratt & Whitney Canada PW100. The aircraft has been delivered in four series. The Series 100 has a maximum capacity of 39, the Series 200 has the same capacity but offers more powerful engines, the Series 300 is a stretched, 50-seat version, and the Series 400 is further stretched to 78 passengers. Models delivered after 1997 have cabin noise suppression and are designated with the prefix "Q".^[5]Production of the Series 100 ceased in 2005, and the Q200 and Q300 in 2009. Bombardier is considering launching a stretched version of the Q400.

In the 1970s, de Havilland Canada had invested heavily in its Dash 7 project, concentrating on STOL and short-field performance, the company's traditional area of expertise. Using four medium-power engines with large four-bladed propellers resulted in very low noise levels which, combined with its excellent STOL characteristics, made the Dash 7 suitable for operating from small in-city airports, a market DHC felt would be compelling. However, only a handful of air carriers employed the Dash 7, as most regional airlines were more interested in operational costs than short-field performance.

In 1980, de Havilland responded by dropping the short-field performance requirement and adapting the basic Dash 7 layout to use only two, more powerful engines. Its favoured engine supplier, Pratt & Whitney Canada, developed the new PW100 series engines for the role, more than doubling the power from its PT6. Originally designated the PT7A-2R engine, it later became the PW120. When the Dash 8 rolled out on April 19, 1983, more than 3,800 hours of testing had been accumulated over two years on five PW100 series test engines. Certification of the PW120 followed in late 1983.^[6]

Distinguishing features of the Dash 8 design are the large T-tail intended to keep the tail free of prop wash during takeoff, a very high aspect ratio wing, the elongated engine nacelles also holding the rearward-folding landing gear, and the pointed nose profile. First flight was on June 20, 1983, and the airliner entered service in 1984 with NorOntair. In 1984, Piedmont Airlines, formerly Henson Airlines, was the first US customer for the Dash 8.

The Dash 8 design has better cruise performance than the Dash 7, is less expensive to operate and much less expensive to maintain, due largely to having only two engines. The Dash 8 has the lowest cost per passenger mile of any regional airliner of the era. It was a little noisier than the Dash 7 and could not match the STOL performance of its earlier DHC forebears, although it was still able to operate from small airports with 3,000 ft (910 m) runways, compared to the 2,200 ft (670 m) required by a fully loaded Dash 7.

In April 2008, Bombardier announced that production of the Classic versions (Series 100, 200, 300) would be ended, leaving the Series 400 as the only Dash 8 still in production. 671 Dash 8 Classics were produced, the last one delivered to Air Nelson in May 2008.