On 5 August 2013, the Commission granted conditional approval to a proposed merger between US Airways and the parent company of American Airlines (M.6607). 

The competition concerns of the Commission surrounded the monopoly over the London-Philadelphia non-stop services route that would be held by the merged entity. This situation would arise because US Airways and American Airlines, through its transatlantic joint-venture with British Airways and Iberia (the "Transatlantic Joint Business") are the only carriers offering this non-stop flight.

US Airways and American Airlines submitted commitments to appease the Commission's concerns. These commitments include, releasing a day slot at each London Heathrow and Philadelphia airports, providing incentives for new entrants, entering into special traffic arrangements with new entrant, supported by the Transatlantic Joint Business.

The Commission found that in relation to the other overlapping routes, the merged entity would face continued strong competition. Therefore, the Commission took the view that these commitments address the competition concerns and would facilitate new entry on the London-Philadelphia route.

Conversely, on 13 August 2013 the US Department of Justice announced its intention to file a civil antitrust lawsuit to challenge the merger. The Department fears that the proposed merger would significantly decrease the competition throughout the United States.