mean a relaxation of restrictions on European airlines ' investment in U.S. carriers and the ability for European airlines to compete in the U.S. domestic market . The issue is pending in U.S. Congress . If the U.S. does n't deliver , there is a clause in the agreement that states the Open Skies treaty -- phase I included -- can be torn up . Industry experts foresee some fare wars in both economy and business-class . Service options are also likely to improve as competition intensifies . U.S. airlines will vie with BA , the dominant carrier at Heathrow , that currently has flights to 24 U.S. cities . The biggest challenge to the incumbent airlines operating out of Heathrow will come from carriers in the SkyTeam alliance , that includes Air France and KLM , Delta Air Lines , Northwest Airlines News , and Continental Airlines . Before Open Skies , the SkyTeam alliance offered no transatlantic routes to and from Heathrow . By summer they will offer 10 percent of these flights . SkyTeam carriers will be located for the first time in Terminal 4 . Given the size of the market for U.S.-London flights , airlines
LONDON , England -LRB- CNN -RRB- -- On March 30 the Open Skies treaty went into effect , liberalizing air travel between the U.S. and Europe . But how will the ease of restrictions on transatlantic routes affect business travelers ? Under Open Skies , European and U.S. airlines will be given unlimited access between Europe and U.S. points . The treaty puts an end to the exclusive arrangement granted to British Airways , Virgin Atlantic , United Airlines and American Airlines to fly transatlantic out of London Heathrow . But with the airport currently operating at almost-maximum capacity , new flights will be severely limited . As a result competition is fierce for Heathrow slots , with airlines paying as much as $ 60 million to get their hands on them . For each flight that is added , another less lucrative service is scrapped . Airlines are giving priority to high-yield business routes to and from Heathrow . While European carriers are now allowed to fly from any point within E.U across the Atlantic , the U.S. domestic market remains closed to them . Operators in Europe hope that a second phase of the Open Skies deal will