Oslo OSL to Tallinn TLL flight with Norwegian Air Shuttle

SAS, or Scandinavian Airlines, is the national airline of Denmark, Norway, and Sweden, headquartered in Solna, Sweden. Founded in 1946, it emerged from a merger of the three countries' national carriers to handle transatlantic operations. SAS operates extensive regional services within Scandinavia and Europe, as well as international flights to Asia and North America, with primary hubs in Copenhagen, Stockholm, and Oslo. As of July 2024, SAS, including its subsidiaries SAS Link and SAS Connect, operates a fleet of 133 aircraft to 130 destinations. SAS joined SkyTeam on September 1, 2024, after leaving Star Alliance.

Norwegian Air International (NAI) was an Irish airline and a fully integrated subsidiary of Norwegian Air Shuttle, operating under its corporate identity. Headquartered at Dublin Airport, NAI operated flights to destinations across Europe and the Middle East from various European bases. Between 2017 and 2019, it also offered services from Europe to the United States and Canada. NAI received its operating license and air operator's certificate from Ireland in February 2014, allowing it to leverage European Union airline freedoms. By April 2021, its aircraft and operations were gradually transferred to its Swedish sister airline, Norwegian Air Sweden, and its parent company.

CityJet is an Irish regional airline headquartered in Dublin, Ireland. Founded in 1992, it began operations in 1994, initially flying between Dublin and London City Airport under a franchise agreement with Virgin Atlantic. CityJet transitioned its business model in 2018, ceasing its own-brand scheduled services to focus on wet leasing aircraft to other European airlines. This means CityJet provides aircraft and crew to operate flights on behalf of other carriers. As of 2023, CityJet operates a fleet of Bombardier CRJ900 and CRJ1000 aircraft, primarily for airlines like Scandinavian Airlines (SAS), Lufthansa, and Brussels Airlines. In 2023, CityJet merged with Air Nostrum, forming the Strategic Alliance of Regional Airlines (SARA).

A regional jet (RJ) is a jet-powered regional airliner typically designed to carry fewer than 100 passengers on short-haul flights. These aircraft are often used by regional airlines, which may operate independently or as subsidiaries contracted by larger carriers, to connect smaller markets to major airline hubs. Key manufacturers of regional jets include Embraer and Bombardier, with Embraer's E-Jet family being particularly popular. Regional jets play a crucial role in providing air service to communities that may not have sufficient demand for larger aircraft, facilitating connections within a country or a specific area of a continent.