Horizon Air (QX, Seattle Tacoma International) operated its last revenue DHC-8-Q400 service on January 26, 2023, and has, for the first time in its history, now become an all-jet operator.

The wholly-owned Alaska Air Group subsidiary operated thirty Dash 8-Q400s as of mid-2022. It began gradually parking the aircraft in the second half of the year and entered 2023 with just nine active turboprops. The final four operated their last flights on January 26: N443QX (msn 4353), N435QX (msn 4232), N453QX (msn 4489), and, finally, N421QX (msn 4149), which concluded the type's history with Horizon Air during the evening flight from Spokane International to Seattle Tacoma International, followed by a non-revenue ferry flight to Portland International.

January 26 was selected for the final flights as it marked exactly 22 years since the airline's first commercial Q400 flight in 2001.

The majority of Horizon Air's Q400s were owned by the airline. The carrier also leased six units retired in the second half of 2022 from BCC Equipment Leasing, the ch-aviation fleets ownership module shows.

Following the retirement of the Q400s, Horizon Air will continue to operate thirty-three E175s (and seventeen more on order) on behalf of Alaska Airlines. Although the airline launched with a turboprop-only fleet comprising Fokker 27s in the early 1980s, for most of its history, it has operated both turboprop aircraft (including, historically, Dash 8-100s, Dash 8-200s, Do328-100s, and Metroliners) and regional jets (Fokker 28-4000s and CRJ700s), the ch-aviation fleets history module shows.

The retirement of the De Havilland Aircraft of Canada turboprops is part of Alaska Air Group's fleet simplification strategy, which centres on B737 narrowbody aircraft and E175 regional jets.