A single UK hub airport is the only viable option to support Northern Ireland's trade with countries such as Brazil and China, the region's chamber of commerce has said.
Heathrow bosses are keen to see a third, extra, runway at the west London airport but this has been ruled out for the time being by the Government at Westminster, where there have been calls for alternative airfields to be developed.
A report from the airport said the UK needed one hub to compete with Europe.
Northern Ireland Chamber of Commerce chief executive Ann McGregor said: "To support trade and Northern Ireland's economy, it is vital for our firms to have connections to these emerging markets. As this report shows, a single hub airport is the only viable option to make this a reality."
Lack of capacity at Heathrow is already costing the UK up to £14 billion a year in lost trade, according to the airport's submission. This figure could rise to £26 billion a year by 2030. Some residents near Heathrow and environmentalists are fiercely opposed to expansion.
Ms McGregor said encouraging increased trade with overseas markets was vital to rebalancing Northern Ireland's economy away from over-reliance on the public sector.
"While firms are being urged to trade with new partners in emerging markets, they are hindered by the lack of connections to these countries, in turn hurting both inward investment and Britain's export potential," she said.
"This is a real issue for Northern Ireland as we have dozens of members that trade with or aspire to do business with the likes of Brazil, India and China."
The report said having a dual-hub plan, where two airports would serve as hub airports, would not work. It also ruled out as "unviable" the so-called Heathwick plan, where Heathrow and Gatwick would be joined by a rail link.
The report will be submitted to the Davies Commission by Heathrow bosses. The report said that Heathrow operates at 99% capacity and that there was no room to fit in new trade routes to the emerging economies which were important for future economic growth.