1958 — Apr 21, United 736 & USAF F-100 Fighter collide mid-air, near Las Vegas, NV– 49

— 49 Aviation Safety Network. Accident Description. United Air Lines Flight 736, 21 Apr 1958.
— 49 Baugher, Joseph F. 1956 USAF Serial Numbers (56-957/6956). 1-4-2012 revision.
— 49 Civil Aeronautics Board, Aircraft Accident Report. United Air and USAF F-100F Collision.
— 49 Gero. Aviation Disasters: The World’s Major Civil Airliner Crashes Since 1950 (2nd. Ed.). 1996.
–47 DC-7 (42 passengers and five crew members)
— 2 F-100 (instructor and trainee)
— 49 Planecrashinfo.com. Accident Details. United Air Lines / Military USAF, Apr 21, 1958.
–47 United Air Lines DC-7 942 passengers and 5 crew)
— 2 USAF F-100F pilots
— 49 Scroggins, Doug. “Historical Mishap: Remembering Flight 736.” Lost Birds.com
— 49 Sturkey. Mayday. Accident Reports…Voice Transcripts…Airline Crash Investigations. 2005, 87.
–47 aboard (all); United Airlines Flight 736.
— 2 USAF F-100 Super Sabre fighter.
— 47 AirDisaster.com. Accident Database. Accident Synopsis 04211958.

Narrative Information

AirDisaster.com: “Enroute from Los Angeles to Denver at Flight Level 210, the DC-7 collided with a U.S. Air Force F-100 fighter jet. The USAF pilot ejected safely [incorrect] – all 47 aboard the DC-7 were killed.” (AirDisaster.com. Accident Database. Accident Synopsis 04211958.)

Aviation Safety Network: “United Air Lines Flight 736, a DC-7, took off from Los Angeles (LAX) at 07:37 on an IFR flight to New York (JFK) with a planned cruising altitude of FL210. [Crew of 5, and 42 passengers.]

“At about 07:45 a US Air Force North American F-100F-5-NA Super Sabre fighter (56-3755) took off from Nellis AFB on an instrument training flight [crew of two]. During the exercise the flight was executing a simulated jet penetration in the area of Las Vegas, NV. At 08:30 the fighter plane pilot reported that they were descending from FL280 near the KRAM radio station. At the same time, United flight 736 was approaching the Las Vegas VOR. Both aircraft collided at FL210, 9 miles SW of Las Vegas VOR station on Victor Airway 8. Initial contact occurred between the leading edge of the DC-7 right wing and the leading edge of the F-100 right wing, 132 inches outboard of the aircraft centerline. It was determined that the DC-7 was flying at about 312 knots on a 23 deg. heading and the F-100 at 444 knots on a 145 deg heading. Assuming a small descent angle of the F-100, the closure speed was about 665kts. Both planes crashed out of control.” (Aviation Safety Network. Accident Description. United Air Lines Flight 736, 21 Apr 1958.)

Baugher: “North American F-100F-5-NA Super Sabre….3755 collided with United Airlines DC-7 N6328C 9 mi SW of Las Vegas, NV Apr 21, 1958. All 42 passengers and 5 crew members aboard DC-7 killed; both crew aboard F-100F killed.” (Baugher, Joseph F. 1956 USAF Serial Numbers (56-957/6956). 1-4-2012 revision.)

Civil Aeronautics Board Synopsis:

“On April 21, 1958, about 0830, an Air Force F-100F and a United Air Lines DC-7 collided at 21,000 feet over a position about nine miles southwest of the Las Vegas VOR station [very high frequency omnirange station]. The position was on Victor Airway 8 about 1¾ miles to the right (southeast) of the centerline. Both aircraft fell uncontrollable and crashed, killing the 42 passengers and 5 crew members of the DC-7 and the 2 Air Force pilots of the F-100F.

“The accident occurred in clear weather conditions while the DC-7 flight, from Los Angeles to New York [scheduled stop in Denver (Gero)], was proceeding normally according to an IFR (Instrument Flight Rules) flight plan and clearance, and while the F-100F was executing a simulated jet penetration, part of an instrument training flight which originated at Nellis Air Force Base. The flight was according to a local VRF (Visual Flight Rules) flight plan.

“The accident occurred in FVR conditions which, under the Civil Air Regulations, placed responsibility on the pilots of both aircraft to avoid collision through visual separation. This collision was the result of a high rate of near head-on closure at high altitude together with the human and cockpit limitations.

“The accident occurred during an Air Force instrument training operation pursuant to Air Force policies which did not take adequate account of human limitation to avoid collision by visual means although the limitations were recognized in other training operations and were known to the Air Force.

“The Civil Aeronautics Administration did not take sufficient measures to reduce known collision exposure in visual flight conditions.

‘Nellis AFB operational personnel, after the accident, took numerous steps which recognize the limitations of visual separation and which will reduce the collision exposure on the airway structure in the Las Vegas area.

“The CAA has instigated a program of civil-military coordination, including the review of jet penetrations on a national scale. The goal in this undertaking is also to reduce collision exposure by segregating more effectively high-speed aircraft operations.

“It has long been apparent that the possibility of collision increases markedly with very high closure rates of modern high-speed aircraft. Recognizing the limitations of the capability of visual separation by pilots under such circumstances, the Board has embarked on a regulatory program to require a positive control system to the extent that air traffic control facilities will permit. The initial step toward positive control at high altitude has been taken; however, because its implementation is governed by air traffic control capability, the ultimate goal as currently projected is several years away. In the meantime numerous other steps have been taken, or are under study, to ensure a reduction in collision exposure, and of course all parties operating high-speed aircraft must exercise the utmost caution during this interim period.” (pp. 1-2)

“Probable Cause

“The Board determines that the probable cause of this collision was a high rate of near head-on closure at high altitude; human and cockpit limitations; and the failure of Nellis Air Force Base and the Civil Aeronautics Administration to take every measure to reduce a known collision exposure.” (Civil Aeronautics Board, p. 19.)

Gero: “….The fighter had initiated an evasive maneuver and the airliner probably began one just before the collision, and the former was banking to the left at the time of impact. Its right wing slashed into the right outer wind of the DC-7, shearing off these sections from both aircraft. Both crews were able to transmit ‘Mayday’ distress messaged during their fall to earth, and the instructor pilot in the front seat of the F-100 ejected at a low altitude [but too late to survive] before the jet crashed.

“….training operations out of Nellis Air Force Base were being conducted largely within the confines of several airways, and…numerous close encounters with military jets had been reported by airline crews for more than a year prior to the tragedy….” Gero. Aviation Disasters. 1999, p.29.)

Planecrashinfo.com: “The DC-7 was en route from Los Angeles to Denver flying at 21,000 ft. The military jet was on a training mission being conducted under VFR. The fighter initiated an evasive maneuver just prior to colliding with the airliner. Both trainee and instructor aboard the F-100 were killed along with all forty-seven aboard the DC-7 airliner. A high rate of near head-on closure at high altitude, human and cockpit limitations and the failure of Nellis Air Force Base and the Civil Aeronautics Administration to take measures to reduce a known collision exposure as training exercises were allowed to be conducted within the confines of several airways after numerous close calls with military jets had been reported by airline crews for more than a year prior to the tragedy.” (Planecrashinfo.com. Accident Details. United Air / Military USAF, Apr 21, 1958.)

Scroggins: “On the morning of April 21, 1958, at the Los Angeles international airport, United Airlines Flight 736 a Douglas DC-7 (N6328C) departed from runway 25 left at 7:35 a.m Flight 736 would make several intermediate stops on its way to New York,¬ its final destination. They included Denver, Colorado; Kansas City, Missouri; and Washington, D.C. The crew of Flight 736 was comprised of Captain Duane Ward, First Officer Arlin Summer, Flight Engineer Charles Woods, and Stewardesses Pauline Murray and Yvonne Peterson. A total of 42 passengers were on the flight.

“At Nellis Air Force Base in Las Vegas, Air Force 755 a North American F-100F serial number 56-3755 took-off from runway 4. The aircraft turned, heading southwest. In the front seat, Capt. Tom Coryell, the flight instructor would have a clear view outside, but in the back seat under the hood was his student, 1st Lt. Jerald Moran. They headed for a designated training area, south of Las Vegas.

“Just minutes out from the F-100F , United Flight 736, cruising at an altitude of 21,000 feet, was approaching the Las Vegas area. The crew of Flight 736 was unaware of the approaching high-speed jet traveling at more than 300 knots. Within a split second, Collision! Nearly head on, both aircraft clipped their outer right wing tips, slicing off more than 10 feet from the DC-7, and ripping both the right wing and right stabilizer off the F-100F. Soon after the collision witness saw…the two aircraft fall earthward. All 47 on Flight 736 and the two on Air Force 755 were killed on impact.” (Scroggins, Doug. “Historical Mishap: Remembering Flight 736.” Lost Birds.com.)

Sturkey: “….The F-100 had first flown in 1953, and North American would build 2,294 of these warplanes before production would end in 1959. The F-100 was the world’s first production airplane capable of flying faster than the speed of sound in level flight. Heat-resistant titanium was used extensively in the airframe. Powered by a single afterburning Pratt & Whitney J-57 turbojet, the F-100 had a range of over 1,000 miles and a service ceiling of 55,000 feet. The swept-wing supersonic fighter was armed with four 20mm cannons and equipped to fire missiles and rockets. It had been designed to carry a nuclear bomb. However, it would make its combat debut in Vietnam in the 1960s as a fighter-bomber armed with conventional ordnance.

“The pilot, a captain, had been flying in the Air Force since 1953 and had logged 1,542 flight hours. His student a second lieutenant, had 363 hours in his logbook. He was transitioning into the F-100, in which he had flown a mere four hours. Both pilots and their Super Sabre were based at Nellis….

“The F-100 instructor pilot radioed Nellis VFRE Control and got clearance for a simulated instrument penetration from 28,000 feet. At 0828 Hours the student pilot chopped his power, popped his speed brakes, dropped his nose, and began a rapid descent….

“As the DC-7 airliner cruised straight and level at 21,000 feet along the airway Victor 8, the F-100 fighter was diving earthward….

“At 0831 the F-100 and the DC-7 collide at 21,000 feet….”

“….The F-100 and the DC-7 use different radio frequencies, so the pilots can not hear radio messages to or from the other plane…

“None of the pilots had been informed of the presence of the other aircraft. Yet, the military pilots knew they were crossing Victor 8. Also, the civil pilots knew that military aircraft crossed the airway. The two aircraft had raced toward each other at a closure rate only slightly less than the speed of sound. Under these high-speed conditions, investigators [CAB] agreed that the pilots had only a minimal opportunity to see the other aircraft and take evasive action….

“The Air Force agreed I principle that existing civil and military ATC [air traffic control] capability had not been adequate. After an exhaustive analysis the military investigative team detailed the Primary Cause of the collision and crashes as follows:

The Primary Cause of this accident was the inadequacy of the present [air traffic] control system, which allows two or more aircraft to occupy the same airspace at the same time and relies solely on the ability of pilots to see and avoid one another.

“A major Contributing Cause, as described by insightful military investigators, pinpointed the inadequacy of the VFR see-and-be-seen concept in the modern high-speed aircraft era:

A Contributing Cause is the high rate of closure in resent-day high-speed aircraft which exceeds the limits of human reaction time [Sturkey emphasis]….”

(Sturkey. Mid-Air Collisions. 2005, pp. 87-90 and 93.)

Sources

AirDisaster.Com. Accident Database. Accident Synopsis 04211958. Accessed at: http://www.airdisaster.com/cgi-bin/view_details.cgi?date=04211958&reg=N6328C&airline=United+Airlines

Aviation Safety Network, Flight Safety Network. Accident Description. United Air Lines Flight 736, 21 Apr 1958. Accessed 3-9-2009 at: http://aviation-safety.net/database/record.php?id=19580421-0

Baugher, Joseph F. 1956 USAF Serial Numbers (56-957/6956). 1-4-2012 revision. Accessed 2-21-2012 at: http://www.joebaugher.com/usaf_serials/1956_2.html

Civil Aeronautics Board Aircraft Accident Report. United Air Lines, Inc., IC-7, N 6328C, and United States Air Force F-100F, 56-3755, Collision, Near Las Vegas, Nevada, April 21, 1958. Released 8-19-1958. Accessed 1-31-2023 at: https://ia804502.us.archive.org/11/items/cab-aar-1958-04-21-united-736-usaf-f-100-f/CAB-AAR%201958-04-21-United-736-USAF-F100F.pdf

Gero, David. Aviation Disasters: The World’s Major Civil Airliner Crashes Since 1950 (Second Edition). London: Patrick Stephens Limited, 1996.

Planecrashinfo.com. “1958…Accident Details…United Air Lines / Military USAF, Apr 21, 1958.” Accessed at: http://www.planecrashinfo.com/1958/1958-19.htm

Scroggins, Doug. “Historical Mishap: Remembering Flight 736.” Lost Birds.com. Assessed 7.24/2009 at: http://www.lostbirds.com/UAL736wreckLB.html

Sturkey, Marion F. Mayday. Accident Reports and Voice Transcripts from Airline Crash Investigations. Plum Branch, SC: Heritage Press International, 2005.