LOS ANGELES -- United Airlines plans to install slimmer seats next year on some of its planes, enabling the airline to squeeze in more passengers.

The Chicago-based airline said it would add the seats manufactured by German company Recaro Aircraft Seating to its fleet of 152 narrow-body Airbus planes.

The padding on the Recaro seats is thin enough that United can add a row of seats on each plane without reducing legroom, the airline said. The use of an aluminum frame also makes the seat lighter, according to the manufacturer.

In the Airbus planes, United now offers 12 to 15 rows of economy seating, depending on the airplane model. Another row would add up to six seats.

United is not the first to turn to slimmer seats to pack more passengers per plane. Alaska Airlines and Southwest Airlines this year separately announced plans to install slimmer, lighter seats to increase passenger capacity.

In 2010, Florida-based Spirit Airlines started installing seats that are not only thinner but also nonadjustable, allowing the airline to fit up to 33 more passengers per plane.