The American Department of Transport (DOT) has issued a tentative decision approving antitrust immunity for American Airlines and its oneworld partners, allowing the formation a global alliance.

If granted final approval, the decision will allow the oneworld Alliance to join Star and SkyTeam – both of which have operated with antitrust immunity in the USA for some time – in the North American market.

The alliance includes American Airlines, British Airways, Royal Jordanian Airlines, Finnair and Iberia Airlines.

It is hoped an immunised alliance would strengthen the competitiveness of London Heathrow vis-à-vis, Paris Charles De Gaulle, Germany’s Frankfurt and Amsterdam’s Schiphol airports.

“If the decision is made final, American and its “oneworld” alliance partners British Airways, Iberia Airlines, Finnair and Royal Jordanian Airlines would be able to more closely coordinate international operations in transatlantic markets,” the DOT said in a press release.

However, the DOT also argued any potential alliance could harm competition on select routes between the United States and London’s Heathrow Airport - due to limited number of landing and takeoff slots. In response, officials requested oneworld make four pairs of slots available to competitors for new US-Heathrow services.

The decision was welcomed by the Business Travel Coalition (BTC), which said in a statement: “While we are still reviewing the details, we are pleased the DOT’s expert analysis was consistent with much of BTC’s formal comments in the proceeding.

“Corporate travel departments in the U.S. and Europe will now be able to aggressively leverage professional procurement processes to their benefit.

Interested parties have 45 days to object and answers to objections will take a further 15 days.