A daily Heathrow-Seattle service is planned by Delta Air Lines from next spring.
The route application was made yesterday in anticipation of the US carrier receiving anti-trust immunity later this year for its transatlantic joint venture with Virgin Atlantic.
Both carriers are awaiting US Department of Transportation approval.
Delta announced plans in December to acquire 49% of Virgin Atlantic and last month obtained unconditional clearance from the European Commission and the US Department of Justice for the investment.
The two airlines launched reciprocal codesharing across 108 routes to 66 destinations in North America and the UK earlier this month.
The Seattle service will see Delta operating 10 daily non-stop flights from Heathrow to Detroit, Minneapolis, New York-JFK, Boston and Atlanta.
Tickets for the Seattle route are due to go on sale from Saturday (July 27) with flights starting from London on March 30, 2014.
Delta will use a 210-seat Boeing 767-300ER with 35 full flat-bed seats in BusinessElite, 32 seats in Economy Comfort and 143 Economy class seats.
The Heathrow link will mean Delta operating flights to eight international destinations from Seattle, one of the carrier’s fastest growing US gateways.
The airline added routes to Shanghai and Tokyo-Haneda in June, complementing a long-established service to Tokyo-Narita. Delta has also served Beijing and Osaka in Japan from Seattle since 2010.
Marketing, network planning and revenue management executive vice president Glen Hauenstein said: “Our international expansion in Seattle is possible because of our partnerships with Alaska Airlines, Virgin Atlantic and Air France-KLM.
“Together the airlines can provide customers in the Pacific Northwest with an unmatched global network and an industry-leading customer experience on the ground and in the air.”