The loss of the open skies agreement following Brexit would have a "terrible" impact on the airline industry, the boss of Jet2 has warned.
Steven Heapy spoke to this newspaper as the airline confirmed it was adding eight routes to Belfast International Airport, including six that are new to Northern Ireland.
The airline will now fly to Antalya in Turkey, Costa De Almeria in Spain, the Greek island of Crete, Madeira, Malta, Naples in Italy, Paphos in Cyprus and Rhodes. Jet2 already operates a number of flights to Spain, the Canaries and eastern Europe from Belfast.
The move is expected to create around 50 new jobs.
"We've been looking at Belfast International Airport for some time with a view to expansion," Mr Heapy said.
"Our brand and products are becoming increasingly popular, especially with the local travel agents, and we've had a lot of support from them.
"We've decided to put a fourth aircraft into Belfast. It's different from the existing three, because it's a (Boeing) 737-800, which is bigger and has a longer range, and that has allowed us to reach some of the new destinations."
The flights start in April and May next year, and seven will fly once a week, while the Costa De Almeria link is twice a week.
But Mr Heapy said that if demand was strong, the airline could look at increasing the frequency of the services.
He said he believed competition was "a healthy thing", with Jet2 now going head-to-head with Ryanair.
Speaking about concerns over what will happen if the open skies agreement, which allows carriers to fly anywhere within the EU, is scrapped after Brexit, he said: "There are a lot of concerns around Brexit. There's freedom of movement, of capital, of labour and open skies.
"Probably the biggest of that is the open skies. It's our job as the airline and tour operator community to communicate with the Government to put forward the case for aviation and travel. They really need to make sure they deliver open skies, because if we didn't have that, or have anything less than what we have now, it would be terrible for the industry and terrible for people who want to travel."
He said without the agreement it would be very hard to "operate or launch" routes.
Speaking about the new routes, Graham Keddie, managing director of Belfast International Airport, said: "Of course, with the welcome expansion will come new employment opportunities.
"Up to 50 jobs spread throughout the airport will have to be filled, including ground crew, pilots and cabin crew, which will mean £1.5m in wages injected into the local economy."