FILE - In this July 3, 1956, file photo, a burned area shows where a United Airlines UAL DC-7 crashed on Saturday, June 30, 1956, after a mid-air collision with a TWA Flight 2 Constellation, killing a total of 128 people. Wreckage lies at top of butte with vertical cliffs on each side. On Tuesday, July 8, 2014, the Grand Canyon National Park will mark the designation of the crash site as a National Historic Landmark in a ceremony overlooking the gorge where the wreckage was scattered over 1.5 square miles. (AP Photo/David F. Smith, File)