A <a href="https://en.wikipedia.org/wiki/Trans_World_Airlines" id="mw-A" rel="mw:WikiLink" title="Trans World Airlines">TWA</a> <a href="https://en.wikipedia.org/wiki/Lockheed_Constellation" id="mw-Q" rel="mw:WikiLink" title="Lockheed Constellation">Super Constellation</a> and a <a href="https://en.wikipedia.org/wiki/United_Airlines" id="mw-g" rel="mw:WikiLink" title="United Airlines">United Airlines</a> <a href="https://en.wikipedia.org/wiki/Douglas_DC-7" id="mw-w" rel="mw:WikiLink" title="Douglas DC-7">DC-7</a> <a href="https://en.wikipedia.org/wiki/1956_Grand_Canyon_mid-air_collision" id="mw_A" rel="mw:WikiLink" title="1956 Grand Canyon mid-air collision">collide</a> above the <a href="https://en.wikipedia.org/wiki/Grand_Canyon" id="mw_Q" rel="mw:WikiLink" title="Grand Canyon">Grand Canyon</a> in <a href="https://en.wikipedia.org/wiki/Arizona" id="mw_g" rel="mw:WikiLink" title="Arizona">Arizona</a> and crash, killing all 128 on board both airliners.