SAN DIEGO -- Southwest Airlines will temporarily abandon its open-seat boarding policy on certain flights out of San Diego starting Monday as part of a test designed to determine if assigned seating is more efficient.

Southwest is the only major U.S. airline without assigned seating.

The tests, which will run for several weeks, will be conducted on 200 select departures from Lindbergh Field and include several different boarding methods to see how much time it takes to "turn" aircraft.

"We want to make sure that we have studied all the possibilities and aspects of assigned seating before we make any change to what has been a very successful formula for the past 35 years," said Southwest Airlines' Chief Executive Officer Gary Kelly.

"This evaluation is an important step to determine the feasibility of assigned seating, but this is only a test," he said.

Southwest said it would consider "customer satisfaction " enhancements, like assigned seating, only if such a move would attract new business and maintain or improve overall operational efficiencies.

Airline staff will monitor customer satisfaction throughout the duration of the test as well as the efficiency and time it takes to board each flight.