United Airlines to charge more for an empty middle seat

United Airlines There’s a new way to persuade customers to pay more on planes: no middle-seat neighbors.

One of the rows on Airbus A321XLRs will have an empty middle seat with a tray table for aisle and window customers to share, the carrier said Tuesday. Seats in the extra legroom section will go on sale later this year, so it’s unclear how much more United will charge. The seating plan is more common on European airlines, where it is sold as business class for short-haul flights.

United later said it might add them to other aircraft beyond its new, long-range narrow-body planes.

The new upselling is just one of many airlines’ campaigns to get their customers to pay more to fly. Last week, Delta Airlines It joins United in launching basic business class and premium economy fares, which do not come with the perks previously included in the ticket. For example, Delta will no longer provide access to its top-tier Delta One lounge or seat selection with its cheapest long-distance business class tickets.

United also said it plans to introduce a set of three economy seats that convert into beds, called “Relax Row,” on some of its wide-body aircraft in March.

Airlines have spent years adding more premium class seats to make larger business class cabins where spending is more flexible. Increasingly elaborate seating bottlenecks have even delayed the delivery of new aircraft.