Credit: Jenn-Marie Mann, a flight attendant with Alaska Airlines, demonstrates how carry-on roller bags fit up on their sides in new larger luggage bins installed a Alaska Airlines 737-900ER airplane, Friday, Oct. 9, 2015 in Seattle. The new overhead compartments, which Boeing calls "Space Bins," can hold six standard-size bags in the same space that used to hold four. Alaska Airlines will be the first to use the new bins, both on new and retrofitted planes. (AP Photo/Ted S. Warren)
United imposes carry-on limit for some fliers
