Both were traveling between 300 and 350 mph. The United plane's propeller and left wing sliced through the TWA's fuselage and cut off its signature triple-fin tail.
The TWA Lockheed Super Constellation, with Capt. Jack S. Gandy in command, nosed over and plummeted as blankets, clothing, magazines and perhaps people shot out the back of the lopped cabin. Thirty seconds later, the 70 passengers and crew were strewn a few hundred feet above the Colorado River, carnage and metal melded into grotesque chaos.
The United Douglas DC-7 took maybe three times longer to hit. Despite losing an engine and the skin and aileron on its left wing, the airliner still had some lift. Capt. Robert F. Shirley fought to pull up and clear the canyon rim.
A minute to 90 seconds after the collision, the Salt Lake City control tower received a garbled radio transmission: "Salt Lake, ah, 718 . . . we are going in." In the background, someone yelled, "Up . . . up." The plane penetrated 20 feet into the sheer wall of a towering canyon butte, annihilating the aircraft and 58 passengers and crew members.
It was the worst U.S. aviation disaster up to that time: 10:31 a.m., June 30, 1956.
The magnitude of the grisly midair crash over one of the world's natural wonders helped spur the federal government to establish the Federal Aviation Administration air traffic control system that now safeguards the skies.
'Sights I never want to see again' • The two flights over the canyon were first-class only. Passengers included TWA and United employees, their families and company executives, the wife of a Detroit mining and real estate magnate, business executives and attorneys, military officers and 14 children, including an infant.
More than 300 children lost one or both parents in the crash.
Though a handful of people claimed to have witnessed the collision, the Civil Aeronautics Board investigative team found all of them unreliable. That meant no one saw the crash, which may have been clearly visible from the main tourist centers on the South Rim.
It wasn't until two brothers who operated a sightseeing flight service spotted smoke June 30 that authorities even knew where to look.
It was immediately clear there would be no survivors.
Military personnel, Swiss and American mountain climbers, river guides and citizen volunteers joined in the recovery effort. Military helicopter pilots made 76 trips to the crash sites over 10 days in heat so blistering and air thermals so unpredictable the pilots risked their own lives.
The operation traumatized them.
"They are sights I never want to see again," Air Force helicopter team member Donald Hunter of Greenfield, Ind., told reporters after seeing the TWA wreckage on Temple Butte. "The most of any person I saw was half a woman."