Delta Air Lines and Virgin Atlantic will this winter transfer operations for direct flights from London Heathrow to Atlanta and Los Angeles.
From October 26, Delta will operate one of the two daily LHR to LAX services that are currently operated by Virgin.
This will be Delta's first nonstop flight between the two cities and its seventh direct service between London and the US.
On the same date, Virgin will begin operating one of Delta's three daily flights between LHR and Atlanta.
The two airlines will codeshare on each other's operated services. They unveiled their initial joint schedule, which began this summer, late last year (see news, November 2013).
Craig Kreeger, Virgin Atlantic CEO, said: "It's great to see how our partnership with Delta is already proving fruitful to our customers.
"In less than a year we will have co-located key business routes, delivered schedule changes to benefit our customers and provided enhanced experiences to our frequent fliers, who gain from reciprocal lounge access and the ability to earn and burn across both carriers.
"This is just the beginning of demonstrating how a true joint venture between airlines should be operated to benefit customers."
Delta President Ed Bastian added: "From the outset we said that our partnership with Virgin Atlantic was about improving services while offering more destinations and schedule choice.
"Expanding access to London's Heathrow Airport has long been at the top of Delta's list of priorities, while Virgin Atlantic has long wanted greater access to North America.
"Today's announcement shows how we’re delivering this shared commitment to increase connectivity on the trans-Atlantic."