Codeshare partners United Airlines and Continental Airlines said Tuesday that starting next year they will allow members of each carrier's frequent flier program who have earned elite status to receive unlimited free upgrades on flights operated by both airlines when space is available.
Continental used to be part of an alliance that includes Delta Air Lines, but is now part of an alliance that includes United. Codeshare agreements allow airlines to sell seats on each other's planes.
The new benefits for elite frequent fliers on United and Continental will begin to roll out in mid-2010, the airlines said in a statement.
Continental Airlines Inc. is based in Houston. United's parent, UAL Corp., is based in Chicago.