Britain and U.S. Reach Post-Brexit Aviation Agreement

The United States and Britain have reached an agreement that removes a cloud that had been hanging over airlines in both countries as Britain’s departure from the European Union approaches.

The deal, reached on Wednesday, will allow flights between the two countries to continue as usual. Those flights are governed by the U.S.-E.U. Air Transport Agreement, which will no longer apply to Britain when Brexit is completed next year.

The announcement “provides much-needed certainty that when the U.K. exits the European Union there will be no disruption to air service for the traveling and shipping public,” said Nicholas E. Calio, the president and chief executive of Airlines for America, a trade group for airlines in the United States.

Airlines for America said that around 20 million passengers and more than 900,000 tons of cargo fly between the United States and Britain every year — about one-third of all flights each year between the United States and Europe.

If an agreement had not been reached, those flights would have been governed by regulations established in the 1970s. That would have meant that joint business agreements like the one between American Airlines and British Airways, in which the two airlines sell tickets on each other’s flights, would have been in danger.

“The alliances that currently schedule and price so-called metal-neutral service would cease to exist, the antitrust immunity would cease to exist,” said Robert W. Mann, an airline analyst based in Port Washington, N.Y. “It’s kind of like off the edge of those old maps of the world, there be dragons,” he added, describing the uncertainty for airlines around the world in the event of a Brexit without a deal with Europe.

Airlines based in the European Union that serve routes between Britain and the United States would have lost the rights to those flights altogether. The agreement preserves their right to continue operating those flights. But any European airlines that want to add new routes between the United States and Britain will require a waiver from the United States government.

Britain has yet to reach an aviation agreement with the Europe Union. A draft Brexit deal that the British government reached with the European Union this month stipulates that the two governments will continue negotiating a “comprehensive air transport agreement.” But that draft Brexit deal still needs the approval of the British Parliament, and its approval is by no means certain.

“There’s still a lot of unknowns there,” Mr. Mann said. Until a deal is reached, there’s no guarantee that flights that passengers booked between Britain and Europe after March 2019 will be permitted to operate. Airlines, he said, “have schedules published that they may not be able to fly.”