On April 21, 1958, the airliner assigned to the flight, a Douglas DC-7 with 47 on board, was flying over Clark County, Nevada in clear weather when it was involved in a daytime mid-air collision with a United States Air Force fighter jet crewed by two pilots.

The loss of Flight 736, one of a series of 1950s mid-air collisions involving passenger aircraft in American skies, helped usher-in widespread improvements in air traffic control within the United States, and led to a sweeping reorganization of federal government aviation authorities.

In one case a judge stated the Air Force pilots did not use "ordinary care" in operation of the fighter jet, and should have yielded the right of way to the DC-7 airliner, despite the investigation assigning no blame to either flight crew for the collision.

[note 1] Soon after taking off, the airliner was directed about 50 miles (43 nmi; 80 km) east through controlled airspace to a waypoint over Ontario, California, where a turn to the northeast towards Las Vegas allowed it to merge with the "Victor 8" airway.

Part of the training flight involved a descent and approach to Nellis Air Force Base from an altitude of 28,000 feet (8,500 m), with an extended speed brake, under simulated instrument meteorological conditions (IMC).

[12] At 8:28 a.m. the F-100F crew requested and received clearance from the military controller at Nellis Air Force Base to begin a procedural "jet penetration" descent to 14,000 feet (4,300 m).

As the fighter descended in a southerly direction, the airliner was approaching Las Vegas air space at about 312 knots (359 mph; 578 km/h) on a north-northeasterly heading of 23 degrees, flying straight and level within the confines of its designated "Victor 8" airway.

The high aerodynamic forces resulting from the spin exceeded the DC-7's stress limits, causing the engines to be wrenched from their mounts, and seconds later the remainder of the aircraft began breaking apart.

[25] At the request of the local sheriff and United Airlines, the Federal Bureau of Investigation sent fingerprint experts to help identify the human remains.

[28] Articles in the Las Vegas Review-Journal commemorating the 40th and 50th anniversaries of the crash reported the FBI search went beyond fingerprint matching for identification; the agents were also looking for any surviving sensitive papers relating to national security the group of military contractors had carried on board in handcuffed briefcases.

[29][30] The same reports also said the crash prompted the military and defense industry to adopt rules to keep groups of technical people involved in the same critical project from travelling together on the same plane.

[32] The CAB report did not assign blame to either flight crew for the accident, but faulted authorities at the CAA and Nellis Air Force Base for failing to take measures to reduce a known collision exposure; training exercises were allowed to be conducted for more than a year prior to the collision within the confines of several airways, even after numerous near-misses with military jets had been reported by airline crews.

[33][34] The CAB acknowledged that the Air Force, following the accident, took numerous steps to reduce the collision exposure on the airway structure in the Las Vegas area.

The Las Vegas crash provides grim emphasis to the argument vigorously pressed by the Deseret News last year, that all military student-training flights be performed out of bounds of commercial airways.

"[37][38] From June 1956 to May 1958—beginning with the high-profile Grand Canyon disaster and concluding with the loss of Capital Airlines Flight 300—in just under two years a total of 245 military and civilian people died in a series of five major United States mid-air collisions involving at least one passenger transport aircraft.

[43] In an editorial published just after the collision, Aviation Week magazine called the loss of Flight 736 "another ghastly exclamation point in the sad story of how the speed and numbers of modern aircraft have badly outrun the mechanical and administrative machinery of air traffic control.

[58] In a judgment in January 1964, surviving relatives of two of the United Airlines crew were awarded a total of $343,200 from the government, with U.S. District Court Judge Olin Hatfield Chilson finding the Air Force pilots did not use "ordinary care" in operation of the fighter jet.

[60][61] The 49 lives lost in this mid-air collision made it the deadliest aviation incident in the history of the Las Vegas region, but the area has experienced two other major airliner crashes.

[63] At both of those rugged, mountainous sites, salvage efforts removed the more accessible wreckage, but scattered portions of the TWA Douglas DC-3 and Bonanza Air Lines Fairchild F-27 were left behind, including the DC-3's radial engines.

[64] Today the spot where the DC-7 crashed is adjacent to the neighborhood of Southern Highlands near the intersection of Decatur Boulevard and Cactus Avenue, amid commercial development.

A small engraved metal cross placed in the sandy soil in 1999 by the son of a victim remained the only sign of the loss of United Airlines Flight 736, but preliminary efforts were in motion to encourage public officials to build a permanent memorial to those who died.

[29] [65] [66] A brief video produced by the Las Vegas Review-Journal in April 2018 says the site where Flight 736 impacted is now beneath a parking lot, but the metal cross was still standing nearby on a low hill that remained undeveloped.