JetBlue Airways is pushing its fleet of single-aisle planes deeper into Europe next year with seasonal daily flights to Milan, Italy, and Barcelona, Spain, from Boston, its latest bid to win over higher-spending vacationers.

Daily service from Boston to Barcelona is set to debut on April 16, and the daily Milan flight from Boston is scheduled to begin May 11, the airline said Wednesday.

U.S. airlines — from JetBlue’s new earn-and-burn miles partner United Airlines to smaller carriers like Alaska Airlines — have been adding international destinations that command higher fares and often have more premium seats on board than shorter domestic flights to help drive profits.

JetBlue has been reworking its network to cut unprofitable routes and add others, especially new destinations served by planes with its profitable Mint business class, as it seeks to stem more than five years of losses. Demand from airlines for more spacious, premium seats has been so high in recent years it has contributed to bottlenecks of new airplane deliveries.

The New York-based airline last month said its first lounge at John F. Kennedy International Airport, which it plans to open this year, will be accessible for trans-Atlantic Mint customers, among travelers.

JetBlue’s first trans-Atlantic flight debuted in 2021 with a nonstop route to London, and it has since added service from both New York and Boston to Paris; Amsterdam; Edinburgh, Scotland; and Dublin.

The new flights go on sale Thursday.

JetBlue’s additions show how airlines are flying newer Airbus narrow-body planes farther.

It will use its A321LR, or long-range, Airbus jets for the Barcelona and Milan flights. The Milan flight will be the longest in JetBlue’s network, at about nine hours westbound and about seven hours and 45 eastbound, a spokesman said, though times can vary based on weather conditions and other factors.

Those planes carry fewer travelers than large twin-aisle jets like Boeing 777s but are cheaper to operate since they require less fuel, among other things. American Airlines plans to debut its Airbus A321XLR, an ultra-long-range version of its popular 321 plane, in December and eventually fly it to Edinburgh from both New York and its Philadelphia hub next March.