The De Havilland Dash-8 Q400 is a twin-engine turboprop regional airliner, designed and manufactured by the Canadian aircraft manufacturer De Havilland Canada. The Q400 was developed as an improved variant of the Dash-8 series in the early 1990s, and first entered service in 1995.

The Dash-8 Q400 was designed to meet the needs of regional airlines for an aircraft with a larger passenger capacity than the smaller Dash-8 models, combined with the performance of a turboprop engine. The Q400 has a capacity of up to 78 passengers and is capable of cruising speeds of up to 350 knots. The Q400 features two Pratt & Whitney Canada PW150 engines, which provide significantly greater fuel efficiency than the earlier Dash-8 models.

The Q400 has become a popular choice for regional airlines, with over 800 aircraft in service as of 2021. The aircraft is especially popular with low-cost carriers, due to its fuel efficiency and passenger capacity. The aircraft has also seen increased demand in recent years as a cargo-carrying aircraft, due to its large cargo capacity and short takeoff distances.

The Dash-8 Q400 has been well-received by passengers and pilots alike, due to its spacious cabin and quiet operation. The aircraft also features a number of innovative technologies, such as a fly-by-wire flight control system, an autopilot system, an advanced avionics suite, and modern cabin amenities. The aircraft also offers increased safety, with a triple-redundant hydraulic system, an independent power source for the flight control system, and an integrated flight data recorder.

The Dash-8 Q400 has faced a few safety issues over the years, such as a number of incidents involving icing and engine failure. However, the aircraft has a strong safety record overall, and the issues have been addressed by De Havilland and the aviation authorities. The aircraft has also been praised for its improved fuel efficiency and lower emissions, compared to other aircraft in its class.

The Dash-8 Q400 is an innovative aircraft, bringing modern technology and increased safety to the regional airline market. The aircraft offers increased passenger capacity and fuel efficiency, while still providing a comfortable and quiet ride for passengers. The aircraft has become a popular choice for regional airlines, and its improved safety features and technology make it a reliable and safe choice for passengers.