Virgin Atlantic and Delta Air Lines will enter into a wide-ranging codeshare agreement covering 108 international routes to 66 destinations from 3 July, following Delta's acquisition of a 49% stake in the UK carrier.
Virgin Atlantic will place its code on 91 Delta services, including transatlantic and domestic US routes such as Chicago and Washington, while Delta will place its code on 17 Virgin routes, including services connecting London to Manchester, Edinburgh and Aberdeen.
Ed Bastian, president of the US airline, says the new partnership will help Virgin and Delta challenge British Airways' "dominance" at Heathrow.
He adds that Virgin passengers "will have greater access to a comprehensive connecting market on a scale not available before".
Meanwhile, the US Department of Transportation's investigation into the Delta-Virgin joint venture is "going quite well, from our understanding", says Bastian. He expects DoT approval "within a few months". This would allow the two airlines to complete their partnership by the first quarter of 2014.
The two airlines would then offer a combined 23 peak-time flights per day from Heathrow to the USA, and an estimated 36% of the seat capacity between New York JFK and London Heathrow airports.
Craig Kreeger, chief executive of Virgin Atlantic, says the carrier's priority is to get the partnership with Delta "right" before considering joining SkyTeam.
Bastian says Delta, which has just launched a new Seattle-Shanghai route, would look at launching a new Seattle-London route in the "near future" following the tie-up with Virgin.