British Airways (BA, London Heathrow) will increase flights between Heathrow and Belfast City after Aer Lingus (EI, Dublin International) confirmed it would cease operating on the route at the end of October. The Aer Lingus decision is attributed to Brexit complexities, including the imminent expiration of the airline's air operator's certificate (AOC) that granted it permission to fly UK domestic routes.

Currently, Aer Lingus operates up to five roundtrip A320 flights a day on the sector. Since the UK left the EU in early 2020, Aer Lingus has operated the route under temporary wet lease provisions. Under the new UK-EU Trade and Cooperation Agreement, EU airlines (Aer Lingus is based in Dublin) must apply for a UK AOC and register aircraft in the UK to operate UK-domestic flights - a stipulation Ryanair Holdings and Wizz Air Holdings have adapted to by establishing Ryanair UK and Wizz Air UK respectively.

"After the UK left the European Union, all UK-based airlines have to operate under a UK operating licence which governs the traffic rights they may hold. Under current legislation and international agreement, EU carriers such as Aer Lingus, are not permitted to operate scheduled services on UK domestic routes," a UK Civil Aviation Authority (CAA) spokesperson said.

"We’ve been flexible with Aer Lingus to find a sustainable solution which satisfies both the requirements of the UK-EU Trade and Cooperation Agreement that no longer relies on the wet-leasing arrangements."

Across November, British Airways' schedules show it will operate between three and four roundtrip services a day on the route using various narrowbody Airbus aircraft. In the week starting October 24, ch-aviation capacities data reveals 18,040 seats are available on the sector, with 8,548 (47.38%) offered by Aer Lingus, 7,308 (40.51%) offered by British Airways, and 2,184 seats (12.11%) provided by flybe. (Birmingham, GB).

Despite making no overt moves to obtain the required AOC to resume UK domestic flights, Aer Lingus says it is keen to return to the route. "We are engaging with the relevant authorities in order to allow us to continue to service this route into the future," a spokesperson said.