A discussion of the dangers of the thermal runaway/chemical reaction problems of laptop batteries notes that restrictions on use might be imposed, since five on-board battery fires in the past two years have been cited by the Federal Aviation Administration (FAA). Several incidents on airplanes in which laptops flamed up are described. In one incident, a United Parcel Service plane full of packages, including lithium-ion batteries, experienced a conflagration while landing in Philadelphia, Pennsylvania, and investigators continue to carefully examine a melted shipment of batteries, although a final ruling on the cause has not yet been made. In all, the Consumer Product Safety Commission has on file 339 documented cases of lithium and lithium-ion batters for portable electronics overheating, smoking, fuming, or exploding since 2003. The FAA started testing of lithium-ion batteries in 2004, and testing continues. The United Kingdom has banned laptops and all other electronics in the cabins of flight from or through the United Kingdom, but many fliers are adamant that they would prefer to be able to carry their laptops. The lithium-ion battery is used in notebooks, MP3 players, and some cellphones, and can hold a charge longer than the competing nickel-metal-hydride battery, which also generates less power. Many rechargeable batteries have been recalled by such companies as Hewlett-Packard (HP), Apple Computer, and Dell.