Southwest Airlines Co., the largest US low-fare carrier, has initiated a new service that allows a customer to get a head start on boarding for extra $10.

A customer who pays the $10 "EarlyBird Check-in" fee will be among the first to board the plane and finds a lot of window seats to choose from. Southwest is known for its free-for-all approach to seat selection.

Southwest's VP for marketing and sales, Kevin Krone, said, "With EarlyBird Check-in, you no longer need to watch the clock or set your alarm to be one of the first customers to check in for a Southwest flight."

Under Southwest's current policy, passengers can begin to check in 24 hours prior their flight. The one, who check in the earliest, gets to board first.

According to analysts, the change, which will take effect from Thursday, indicates company's struggle to keep its business aloft.

Southwest is of the view that the EarlyBird service will enhance its earnings just like Business Select fares, which in 2008 fetched $75 million to the company.