British Airways has confirmed that its all-business London City-New York services will refuel at Shannon while operating westbound.
The Irish airport had been tipped as the likely point for the westbound technical stop.
British Airways is to use 32-seat Airbus A318s on the route and the Shannon refuelling is necessary to give the type the necessary range over the Atlantic.
Eastbound services will be non-stop.
Passengers will be able to arrive at London City just 15min before departure, and clear US arrivals checks while in Shannon, enabling them to bypass the normal processing after landing.
British Airways is to begin the new transatlantic service in autumn next year, operating the route twice-daily.