Airbus' flagship single-aisle jet will complete a 4,100-mile transatlantic passenger flight on Wednesday as more airlines downsize long-haul flights

• Scandinavian Airlines will fly its Copenhagen to Washington, DC flight on Wednesday using a single-aisle plane.
• The 4,100-mile route will be one of the longest ever flown by the aircraft, and the longest scheduled A321neoLR route once officially inaugurated in March.

SAS Scandinavian Airlines will become the latest airline to complete a revenue flight across the Atlantic with a single-aisle plane on Wednesday.

Flight SK925 from Copenhagen, Denmark to Washington, DC is being flown using an Airbus A321neoLR aircraft, replacing the Airbus A330-300 wide-body aircraft typically used on the route. The flight will serve as a test run ahead of scheduled flights between Scandinavia and Newark, Boston, and Washington starting in March.

"Yesterday, our first Airbus A321 LR, a narrow-bodied aircraft suited for longer distances, performed its first flight, and tomorrow, it will fly its first long haul flight between Copenhagen and Washington!" the airline tweeted on Tuesday.

The plane, SAS' second A321neoLR, named "Ása Viking", was delivered to the airline in September. The flight's duration was scheduled for eight hours and 55 minutes to cover a planned distance of 4,161 miles, according to FlightAware.

The Copenhagen-Washington route will become the longest scheduled route flown by the A321neoLR when it officially launches on March 27, according to data from Cirium. It won't break records, though, as Canada's Air Transat flew the longest-ever passenger flight with an Airbus A321neoLR in October 2020, flying more than 4,100 nautical miles from Montreal, Canada to Athens, Greece.

But while SAS may soon take to the top spot, it's only the latest airline to jump on the narrow-body trend. European and Canadian airlines including Aer Lingus, TAP Air Portugal, La Compagnie, Azores Airlines, and Air Transat have been pioneering transatlantic flights with the A321neo family of aircraft since 2019.

JetBlue Airways became the latest airline to inaugurate transatlantic flights with narrow-body aircraft in August when flights launched between New York and London, as Insider experienced firsthand on the first flight.

And the trend isn't limited to Airbus. United Airlines announced in October that its new flights between Newark and Ponta Delgada, Portugal will be operated with narrow-body Boeing 737 Max aircraft.

A common complaint about long-haul flying on single-aisle aircraft is that it has a more compact feel than a wide-body aircraft. And while that may be physiological, an undeniable downside to flying single-aisle aircraft on long-haul routes is that they fly slower than their wide-body counterparts.

JetBlue flights from London to New York, for example, can be scheduled at as much as one-hour longer than its rivals on the route. But most airlines that are downsizing to smaller planes on longer routes are compensating with new seat products that offer a bit more room.

Scandinavian Airlines offers a three-class configuration onboard its A321neoLR aircraft complete with a 22-seat business class cabin, 123-seat economy class cabin, and first-of-its-kind 12-seat premium economy class cabin, The relatively low-density configuration of 157 seats may also help give the aircraft a more spacious feel, as SAS' standard A321 aircraft can seat 198 passengers.

JetBlue similarly outfitted its transatlantic A321neoLRs with only 138 seats across two cabins, including a brand-new Mint business class cabin. Each of the 24-seat Mint seats offers direct aisle access with a closeable door for increased privacy while economy class seats are 18.4-inches wide.

France's La Compagnie offers an all-business class configuration on its A321neo aircraft with just 76 seats, each with lie-flat capabilities, as Insider found during a recent aircraft tour.

Air Transat chose not to go the lie-flat route in its premium economy Club Class, opting instead for 12 recliner seats. But in economy class, seats are 1.5 inches wider than on the larger Airbus A310s that are being replaced by the A321neoLRs, according to the airline.

More airlines will ultimately look to take advantage of more efficient aircraft to save costs, and travelers may have to get used to seeing smaller planes on longer routes.