FILE - In this June 19, 2014 file photo, baggage carts are towed to the Boeing 737 jet at Bill and Hillary Clinton National Airport in Little Rock, Ark., June 19, 2014. Devices powered by lithium-ion batteries are overheating more often during airline flights and passengers often put them in checked bags that go into the cargo hold, where a fire might not be detected as quickly. (AP Photo/Danny Johnston, File)