United Airlines is only U.S. carrier that flies the 787 ; 50 in service worldwide . Comment: The Federal Aviation Administration must still sign off on Boeing 's battery redesign .
United Airlines is only U.S. carrier that flies the 787 ; 50 in service worldwide . The 787 was grounded in January after two battery fires in Boston and Japan . The Federal Aviation Administration must still sign off on Boeing 's battery redesign .