ATLANTA ( TheStreet) -- Wealthy, strategic Delta ( DAL) said it will invest $360 million to acquire 49% of faltering Virgin Atlantic Airways, creating a trans-Atlantic joint venture that will operate up to 31 daily round-trip flights. The flights will include nine daily round trips to London Heathrow from Newark and New York Kennedy airports, mounting a challenge to a route American Airlines ( AAMRQ.PK) and partner British Airways have long dominated, with near-hourly service. Joint venture flights will also serve Atlanta and other key Delta cities. "The partnership allows both carriers to offer a greatly expanded network at Heathrow and to overcome slot constraints, which have limited the growth and competitive capability of both airlines," said Delta and Virgin, in a joint statement. Their 31 daily round-trip flights will include 23 at London Heathrow. "Our new partnership with Virgin Atlantic will strengthen both airlines and provide a more effective competitor between North America and the U.K., particularly on the New York-London route, which is the largest airline route between the U.S. and Europe," said Delta CEO Richard Anderson, in a prepared statement. The joint venture will operate on a "metal neutral" basis with both airlines sharing the costs and revenue from all fights. Passengers will receive reciprocal frequent flyer benefits and shared access to clubs. The airlines will file an application with the U.S. Department of Transportation for antitrust immunity, which would allow a closer relationship and coordination on schedules and operations. The transaction would be reviewed by the U.S. Department of Justice and the European Union's competition regulator and other relevant authorities. Implementation is expected by the end of 2013. Branson was a longtime opponent of a similar arrangement between American and British Airways, and his opposition has been credited with delaying their implementation for years. It is likely that Virgin Atlantic's quirky, Branson-obsessed image may become a casualty of operating in a partnership with the leading U.S. airline. "We have always been known for our innovation and service and have punched above our weight for 28 years," Branson said, in a prepared statement. "That is why our customers love us so much. We will retain that independent spirit but move forward in a strengthened partnership with Delta."