Updated

The days of first-come, first-served seating on Southwest Airlines Co. (LUV) planes could be nearing an end.

The airline is overhauling its computerized-reservation system to add the ability to assign seats and make international flights. Officials say neither change is for sure.

The earliest Southwest could switch to assigned seating, used by every other major U.S. carrier, is 2008, Chief Executive Gary Kelly said Wednesday. The system won't be able to handle the tax and customs information required for international travel until the following year, he said.

In some ways, Southwest has been on the cutting edge of technology in the airline industry. It built a successful Web site — now accounting for more than half of Southwest's ticket sales — long before its rivals.

But in other ways, the Dallas-based carrier has clung to vestiges of its 1970s origins. Only in the last few years did Southwest finally get rid of reusable plastic boarding passes in favor of paper ones that carry information about each passenger.

It is that background that makes consideration of assigned seating notable. Southwest officials have openly considered the idea for years, but the $5 million upgrade of the reservations system will for the first time make it possible.

Kelly said at the company's annual shareholder meeting that Southwest began plans to add the capability of assigned seating in late 2004. Work on the reservation system won't be done until late next year, Kelly said.

Kelly said some passengers prefer assigned seating and others prefer "open seating," the carrier's preferred term for the free-for-all in which customers board in three groups.

Passengers who print out a boarding pass early can find a window or aisle seat. Latecomers are relegated to Group C. Boarding after everyone else, they must schlep their carry-on bags down the aisle while looking for the best remaining middle seats.

While other carriers moved to assigned seating, Southwest has long resisted the idea. Officials have said it could slow down the boarding process — potentially delaying flights.

Chief Financial Officer Laura Wright said the company must determine how switching to assigned seats would affect operations and costs.

"The only way we would do it is if we could keep our low-cost model intact," she said. "We would want it to be cost-neutral."

A Southwest spokeswoman said the airline has never surveyed customers on their preference. Company officials acknowledge only that there are those with strong feelings on both sides.

Until recently, some customers would show up hours early to get in Group A and win a prized seat. Southwest began allowing check-in at airport kiosks or on home computers on the day of the flight.

It now extends that period to 24 hours before the departure time, "so you don't have to wake up at midnight" to print a boarding pass, Kelly joked.