Aer Lingus (Irish: Aer Loingeas) is founded by the Irish government as the national airline of the Republic of Ireland on April 15, 1936.

Aer Lingus is founded with a capital of £100,000. Its first chairman is Seán Ó hUadhaigh. Pending legislation for Government investment through a parent company, Aer Lingus is associated with Blackpool and West Coast Air Services which advances the money for the first aircraft and operates with Aer Lingus under the common title “Irish Sea Airways.” Aer Lingus Teoranta is registered as an airline on May 22, 1936. The name Aer Lingus is proposed by Richard F. O’Connor, who is County Cork Surveyor, as well as an aviation enthusiast.

On May 27, 1936, five days after being registered as an airline, Aer Lingus’s first service begins between Baldonnel Aerodrome in Dublin and Bristol (Whitchurch) Airport in Bristol, England, using a six-seater de Havilland DH.84 Dragon biplane (registration EI-ABI), named Iolar (Eagle).

Later that year, the airline acquires its second aircraft, a four-engined biplane de Havilland DH.86 Express named Éire, with a capacity of 14 passengers. This aircraft provides the first air link between Dublin and London by extending the Bristol service to Croydon. At the same time, the DH.84 Dragon is used to inaugurate an Aer Lingus service on the Dublin-Liverpool route.

Aer Lingus is established as the national carrier under the Air Navigation and Transport Act (1936). In 1937, the Irish government creates Aer Rianta, now called Dublin Airport Authority (DAA), a company to assume financial responsibility for the new airline and the entire country’s civil aviation infrastructure. In April 1937, Aer Lingus becomes wholly owned by the Irish government via Aer Rianta.

Aer Lingus is privatised between 2006 and 2015. It is a former member of the Oneworld airline alliance, which it leaves on March 31, 2007.

Ryanair owns over 29% of Aer Lingus stock and the Irish state owns over 25% before being bought out by International Airlines Group (IAG) in 2015. The state had previously held an 85% shareholding until the Government’s decision to float the company on the Dublin and London stock exchanges on October 2, 2006. The principal group companies include Aer Lingus Limited, Aer Lingus Beachey Limited, Aer Lingus (Ireland) Limited and Dirnan Insurance Company Limited, all of which are wholly owned.

On May 26, 2015, after months of negotiations on a possible IAG takeover, the Irish government agrees to sell its stake in Aer Lingus. Ryanair retains a 30% stake in the company which it agrees to sell to IAG on July 10, 2015, for €2.55 per share. In August 2015, Aer Lingus’ shareholders officially accept IAG’s takeover offer. IAG subsequently assumed control of Aer Lingus on September 2, 2015.

After the takeover by IAG, it is expected that Aer Lingus would re-enter Oneworld, however, at a press briefing on November 15, 2017, the airline’s then CEO Stephen Kavanagh states that the airline has “no plans to join Oneworld.” The airline is now a wholly owned subsidiary of IAG.

Aer Lingus has codeshare agreements with Oneworld, Star Alliance and SkyTeam members, as well as interline agreements with Etihad Airways, JetBlue and United Airlines. The airline has a hybrid business model, operating a mixed fare service on its European routes and full service, two-class flights on transatlantic routes.

Aer Lingus’s head office is on the grounds of Dublin Airport in Collinstown, County Dublin.