This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Southwest Airlines Boeing 737-300The add-on fee trend among the nation’s airlines continues as Southwest Airlines announced Monday a new $40 fee to let passengers board early.

Southwest, the nation’s most popular domestic carrier, already charges $10 for its Early Bird Check-In service, which improves a passenger’s position in the boarding queue.

But the new $40 fee guarantees that passengers get to be among the first 15 in line, letting them stow away carry-on bags in the overhead bin and pick seats with more legroom.

The new boarding option can be purchased at the gate, up to 45 minutes before boarding, and only when space is available, according to Southwest officials.

The fee was tested at the San Diego International Airport last month.