United Airlines Flight 736
Some of the Douglas DC-7 aircraft wreckage collected for the crash investigation.
|Date||April 21, 1958|
|Site||Arden, Nevada, USA|
|Flight origin||Los Angeles, California|
|1st stopover||Denver, Colorado|
|2nd stopover||Kansas City, Missouri|
|Last stopover||Washington, D.C.|
|Destination||New York City|
|Type||North American F-100F-5-NA Super Sabre|
|Operator||United States Air Force|
|Flight origin||Nellis Air Force Base, Nevada|
|Destination||Nellis Air Force Base|
United Airlines Flight 736 was a daily U.S. transcontinental passenger flight operated by United Airlines that crashed on April 21, 1958, following a mid-air collision. The aircraft assigned to Flight 736, a Douglas DC-7 airliner carrying 47 persons, was flying at cruise altitude above Clark County, Nevada, en route to a stopover at Denver, Colorado, when it was struck by a United States Air Force fighter jet crewed by two pilots. The collision occurred at 8:30 a.m. in clear weather within a major commercial airway; both aircraft fell out of control from 21,000 feet (6,400 m) and crashed into unpopulated desert terrain southwest of Las Vegas, Nevada.
There were no survivors from either aircraft, and with 49 fatalities it remains the deadliest crash in the history of the Las Vegas Valley. Among the victims were a group of military personnel and civilian contractors involved with sensitive Department of Defense weapons systems. The loss of the group triggered new rules prohibiting similar groups engaged in critical projects from flying aboard the same aircraft.
The official investigation stated that cockpit visibility limitations played a role in the accident, but also faulted military and civilian aviation authorities for not taking measures to reduce well-known collision risks that had existed for over a year within the confines of airways, despite numerous complaints from airline crews. The loss of United Airlines Flight 736—part of a series of 1950s mid-air collisions in American skies, including the well-publicized 1956 Grand Canyon mid-air collision—helped usher in widespread improvements in air traffic control within the United States.
Events leading to the accident
Flight 736, a four-engined DC-7 propliner with aircraft registration N6328C, departed Los Angeles International Airport at 7:37 a.m. on a flight to New York City with stops in Denver, Kansas City and Washington, D.C. On board were 42 passengers and five crew members; Captain Duane M. Ward, 44, First Officer Arlin Edward Sommers, 36, Flight Engineer Charles E. Woods, 43, and Stewardesses Pauline Mary Murray, 22, and Yvonne Marie Peterson, 27. Of the passengers on the flight, seven were military personnel and 35 were civilians.[note 1]
Soon after takeoff the airliner was directed into airway "Victor 8," on a route that took it east over Ontario, California, and then northeast toward Las Vegas.[note 2] The crew flew the DC-7 under instrument flight rules, controlled by Civil Aeronautics Authority (CAA) ground stations, at an authorized altitude of 21,000 feet (6,400 m) toward the first stopover at Denver. At 8:14 a.m. the United Airlines crew radioed a routine position report over the Mojave Desert to notify controllers that they expected to arrive over McCarran Field near Las Vegas at 8:31 a.m.
At 7:45 a.m. a U.S. Air Force F-100F-5-NA Super Sabre jet fighter, serial number 56-3755, departed Nellis Air Force Base near Las Vegas on a training flight with two pilots on board. In the front seat of the tandem cockpit was flight instructor and safety pilot Capt. Thomas N. Coryell, 29, and behind him sat his student, 1st Lt. Gerald D. Moran, 24, who as part of his training would spend the flight under a hood that blocked his view outside the aircraft, but allowed him to see his instrument panel.
The instructor had two-way microphone communication with the student, and his duties were to instruct the student in the rear seat, monitor his performance and maintain a lookout for other aircraft. The F-100F had dual pilot control and the instructor could take over flying the jet at any time. The training flight involved a descent and approach to Nellis Air Force Base under simulated instrument meteorological conditions from an altitude of 28,000 feet (8,500 m). The descent was to be a "teardrop pattern," with the Las Vegas commercial radio station KRAM as the navigational fix, a process that was referred to as the "KRAM procedure."[note 3] The prescribed descent angle for the KRAM procedure was about five degrees.
Pilot Moran radioed the control tower at Nellis Air Force Base at 8:28 a.m. to report that he would now begin a procedural "jet penetration" descent to 14,000 feet (4,300 m). As the fighter descended, the airliner was approaching Las Vegas air space at about 312 knots (359 mph) on a heading of 23 degrees, flying straight-and-level within the confines of its designated airway. The CAA stations controlling the airliner were unaware of the fighter jet; the Air Force controllers at Nellis Air Force Base directing the jet were unaware of the airliner.
At 8:30 a.m., despite clear skies with excellent visibility of about 35 miles (56 km), the flight paths of the two aircraft intersected about 9 miles (14 km) southwest of Las Vegas. The converging aircraft collided nearly head-on at an altitude of 21,000 feet (6,400 m) at an estimated closure speed of 665 knots (765 mph).
The descending Air Force jet, flying at 444 knots (511 mph), had clipped the airliner's right wing with its own right wing, immediately sending both aircraft out of control. At the moment of collision the F-100F was in a 90 degree bank to the left at a down angle of about 17 degrees. One eyewitness to the collision stated that about two seconds before the collision the wings of the F-100F "dipped"; another eyewitness said the fighter "swooped down" just before the impact. The witness descriptions and the extreme 90 degree bank of the fighter jet—far more than the 30 degrees outlined in the KRAM procedure—suggest an unsuccessful "last second" evasive action on the part of the Air Force crew.
Moments after the two planes collided, the only mayday distress call radioed by the United Airlines crew was heard at 8:30 a.m. plus 20 seconds. The crippled airliner—now missing about eight feet (2.5 m) of its right wing—trailed black smoke and flames as it spiraled earthward, and crashed into a then-empty patch of desert outside the town of Arden. The nearly vertical impact and subsequent explosion instantly killed everyone on board.
The fighter jet—its right wing and right tailplane torn away by the collision—left a trail of fragments as it arced downward, and crashed west of the small community of Sloan into a hilly area of uninhabited desert, several miles south of the DC-7 crash site. At least one of the Air Force pilots was still in the jet when it hit the ground, but contemporary news reports differ on whether the other pilot managed an unsuccessful ejection at too low an altitude to survive, or stayed with the jet all the way to the ground. Witnesses reported seeing a parachute drifting away from the falling F-100F, leading to the hope that a pilot had ejected, but when the parachute was located it was determined to be a drag parachute that is meant to be deployed on landing to help slow the fighter down.
At the request of the local sheriff and United Airlines, the Federal Bureau of Investigation sent fingerprint experts to help identify the human remains. The Los Angeles Times reported that among the dead were 13 civilian and military managers, engineers and technicians assigned to the American ballistic missile program. Articles in the Las Vegas Review-Journal commemorating the 40th and 50th anniversaries of the crash reported that the FBI search went beyond fingerprint matching for identification; the agents were also looking for any surviving sensitive papers relating to national security that the group of military contractors had carried on board in handcuffed briefcases. 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 traveling together on the same plane.
The Civil Aeronautics Board (CAB) conducted an investigation and published a report on the accident. The CAB ruled out the weather conditions and the airworthiness of the two planes as factors in the collision. The report stated the probable cause was the high rate of near head-on closure, and that at high altitude, there were human and cockpit limitations involved. Analysis of the approach angles concluded that a metal frame support on the F-100's windscreen "interfered seriously" with detection of the DC-7, and a supporting pillar on the DC-7's windshield may have hindered sighting the fighter. The CAB accident report also cited a failure of Nellis Air Force Base and the CAA 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.
The mid-air collision involving United Airlines Flight 736, and a second one a month later over Maryland, between a Capital Airlines airliner and another military jet, accelerated efforts in the United States to change the way air space was allocated to commercial and military flights.
On April 22, 1958, the day after United Airlines Flight 736 crashed, the CAB proposed an experiment in which it would set aside part of the air space from which would be barred all aircraft lacking specific clearance to enter it. All aircraft operating in the designated space would have to be equipped for instrument flight operations. According to the CAB there had been 159 mid-air collisions in the years 1947-1957, and that in 1957 alone there were 971 near-misses. The increased speed of aircraft and higher air traffic density made it harder to give pilots enough time to spot each other during flights. Therefore, the CAB said, "it is essential that positive control be extended to altitudes at 35,000 feet and on additional routes as rapidly as practical." At the time such control only existed between 17,000 and 22,000 feet on certain transcontinental airways.
In the wake of the two airliners lost in the April and May 1958 collisions, investigators from a House of Representatives committee—concerned about the lack of coordination between civil and military air traffic controllers—imposed a 60-day deadline on the CAB and the Air Force to establish new control procedures. The committee also said that eventually a single civil agency should be given the power to regulate all air space for all types of aircraft. Furthermore, the committee stated that military flying should be controlled in the vicinity of airways not only in instrument weather, but also in visual conditions.
Four months after 49 lives were lost in the worst aviation accident in the history of the Las Vegas region, the Federal Aviation Act of 1958 was signed into law. The act dissolved the CAA and created the Federal Aviation Agency (FAA, later renamed Federal Aviation Administration). The FAA was given unprecedented and total authority over the control of American air space, including military activity, and as procedures and ATC facilities were modernized, airborne collisions gradually decreased in frequency. The Las Vegas Review-Journal in a 50th anniversary article stated that the act "specifically referenced the crash of United 736 in ordering the creation of the FAA."
The supersonic F-100 left a legacy of many crashes over its years of service; nearly 25 percent were lost to accidents. In particular, 1958 was the most costly, with 47 F-100 pilots killed and 116 of the fighters destroyed, a loss rate averaging almost one every three days.
Following the collision at least 31 lawsuits seeking damages were brought against United Airlines, the U.S. Government, or both. On September 24, 1958, United Airlines filed for damages—based on the Federal Tort Claims Act—against the United States in the U.S. District Court for the District of Delaware. The airline alleged that the United States through its agents in the United States Air Force negligently operated the F-100F, and sought damages of US$3,576,698. The court found neither crew was negligent for a failure to see and avoid each other, but held the United States was liable because of other negligence. The case was settled on December 17, 1962, with the United States agreeing to pay the airline $1.45 million.
In another case, on January 8, 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 Hatfield Chilson finding 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. Chilson also criticized the Air Force for not coordinating instrument training flights with civilian instrument flight rules traffic, and for failing to schedule flights to minimize traffic congestion. The government appealed, and the relatives cross-appealed to have their damage awards increased, but the earlier 1964 judgment was affirmed on September 30, 1965.
Nearby crash sites
The region where the United Airlines and Air Force aircraft went down has experienced other major airliner crashes. In 1942 movie star Carole Lombard and 21 others died in the mountainside crash of TWA Flight 3, about 16 miles (26 km) WSW of where United Airlines Flight 736 crashed. In 1964, 29 people lost their lives when Bonanza Air Lines Flight 114 flew into a hilltop 5 miles (8 km) SW of the United Airlines impact site; the F-100F crashed in the same area of desert hills as the Bonanza Air Lines flight.
At both of those rugged, mountainous sites, salvage efforts removed the more accessible and valuable wreckage, but scattered and sometimes substantial portions of the TWA DC-3 and Bonanza Air Lines Fairchild F-27 were left behind, including the DC-3's radial engines. The United Airlines DC-7 crash site, however, has been cleared of all but the smallest artifacts, and is threatened by development. In 1958 the site was at least a mile from the nearest paved road; today the spot where the DC-7 hit is adjacent to a developed neighborhood near the intersection of Decatur Boulevard and Cactus Avenue. Five decades after the events of April 21, 1958, a small makeshift marker placed in the sandy soil was 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.
- 1958 in aviation
- 1958 in the United States
- Aviation accidents and incidents
- List of accidents and incidents involving military aircraft (1950–1974) - lists eight U.S. military mid-air collisions in 1958.
- List of accidents and incidents on commercial aircraft
- Mid-air collision - includes a list of other notable mid-air collisions.
- Two of the passengers had ironic involvement with air traffic control. Jack R. Fredrick, of the electronics firm Fenske, Fredrick and Miller, had invented a device to enable air traffic control centers to see positions of all aircraft in their control areas on a display panel. He was on his way to Colorado to present his idea to the Air Force. Fellow passenger W. E. Nollenberger was the supervisor of the CAA Air Traffic Division 4, encompassing 11 western states. Four months after Nollenberger's death, the CAA was legislated out of existence, due in part to the crash of the plane he died in.
- "Victor 8 airway was a major transcontinental airway established by the CAA in 1952 and was used extensively by air traffic including large passenger airliners such as United's DC-7. Victor 8 airway includes the navigable air space up to an elevation of 27,000 feet mean sea level above the earth's surface within five statute miles of each side of a prescribed center line. It extends from Long Beach, California, to Washington, D. C., and passes over Las Vegas, Nevada. It was common knowledge that Victor 8 was a regular route for two-way traffic at the time of the accident." – From: United Airlines v. Wiener, 335 F.2d 379, para. 7, U.S. Court of Appeals for the Ninth Circuit, June 24, 1964
- "The KRAM procedure was designed by the command of the Nellis Air Force Base as a procedure to descend from an altitude of 20,000 feet or above to an altitude of 6,000 feet, using as a 'fix' for initiating and concluding the penetration a commercial broadcast radio station (KRAM) located within the boundaries of Civil Airway Victor 8. The procedure prescribed that the Nellis jets, on approaching KRAM, get a clearance for the KRAM penetration from Nellis VFR Control, cross KRAM at 20,000 feet or above, descend on a magnetic track of 170 degrees at 300 knots indicated air speed (approximately the equivalent of 430 knots or 495 miles per hour true or actual air speed under the atmospheric conditions prevailing on the morning of April 21, 1958 at 21,000 feet) to an altitude of 11,000 feet within 16 nautical miles of KRAM. Upon reaching 11,000 feet on a magnetic track of 170 degrees, the procedure prescribed a right turn of 1½ degrees per second and a bank of 30 degrees, and a crossing of the KRAM station at an altitude of 6,000 feet. During the descent it was prescribed that the speed brakes be extended. This procedure is commonly termed a "teardrop penetration" and derives its name from the fact that the path of the plane executing the procedure, if drawn on the earth, would resemble the shape of a teardrop." – From: United States v. Sommers, 351 F.2d 354, note 2, U.S. Court of Appeals for the Tenth Circuit, September 30, 1965
- "L.A. Airliner, Jet Collide; 49 Killed". Los Angeles Times. April 22, 1958. p. 1.
- "Air Space Control Problem Emphasized by Tragic Crash" (PDF). Spokane Daily Chronicle. AP. April 22, 1958. p. 17.
- "335 F.2d 379 para. 7". June 24, 1964. (see Notes for quote)
- "335 F.2d 379 para. 7". June 24, 1964. "At about 8:14, the CAA Centers at Los Angeles and Salt Lake City received a report from Aeronautical Radio, Inc., which serves under contract to United as a radio communicating facility, that Flight 736 had estimated its time of arrival over McCarran Field at Las Vegas, Nevada, at 8:31."
- "Air Age: High Crime?". TIME. May 5, 1958.
- "351 F.2d 354 note 2". September 30, 1965. (see Notes for quote)
- "351 F.2d 354 para. 4". September 30, 1965. "The prescribed angle of descent when executing the maneuver was approximately five degrees."
- "351 F.2d 354 para. 3". September 30, 1965. "the DC-7 was flying in all respects in compliance with the terms of the IFR [Instrument Flight Rules] clearance issued to it by Defendant's agency CAA — straight and level at an altitude of approximately 21,000 feet, and within the confines of the civil airway known as Victor 8"
- "ASN Aircraft accident Douglas DC-7 N6328C Arden, NV". Aviation Safety Network.
- "351 F.2d 354 para. 3". September 30, 1965. "at the time of the collision the weather was clear with visibility about 35 miles"
- "351 F.2d 354 para. 5". September 30, 1965. "There were two eye witnesses to the collision, one of whom testified that about two seconds before the collision the wings of the fighter plane "dipped." The other testified that just before the impact the F-100F "swooped down" onto the DC-7 ... at the time of the impact the F-100F was in a 90 degree bank to the left at an angle of descent of approximately 17 degrees with its speed brakes retracted"
- "Pilot's Frantic Efforts to Dodge Airliner" (PDF). Lewiston Evening Journal. AP. April 29, 1958. p. 8.
- "351 F.2d 354 para. 3". September 30, 1965. "At 8:30 plus 20 seconds the last message from the DC-7 reported the mid-air collision with the Jet fighter."
- "Airliner, jet collision over Nevada Kills 49" (PDF). Ellensburg Daily Record. AP. April 21, 1958. pp. 1, 4.
- Fox, Jack V. (April 22, 1958). "Probers Seek Clues In Airliner Wreckage" (PDF). Deseret News (Salt Lake City). UP. pp. 1, 7.
- "13 Missilemen Among Victims Aboard Plane". Los Angeles Times. April 22, 1958. p. 1.
- Brean, Henry (April 20, 2008). "1958 Crash: Death in Desert Air; Collision of Air Force jet, civilian airliner helped change aviation regulations". Las Vegas Review-Journal.
- Bates, Warren (April 21, 1998). "Sky Fire, Metal Rain; Forty years ago today, a jet fighter and a commercial airliner collided northeast of Las Vegas, killing 49.". Las Vegas Review-Journal. Archived from the original on October 31, 2004.
- Baker, Charles A. (1960). "Visual Aspects in Collision Avoidance of Air Force Aircraft". In (ed. Ailene Morris & E. Porter Horne). Visual Search Techniques. Armed Forces - NRC Visual Research Symposium, April 7–8, 1959. Washington, D.C.: National Academy of Sciences / National Research Council. p. 28. ASIN B001LQZKG6. "Based on an analysis of the approach angles, the opaque ring on the F-100 windscreen would have interfered seriously with the detection of the DC-7. On the DC-7, the corner post between the forward and side windscreen could have interfered with the ability of the airline pilot to see the F-100."
- "Accident details". planecrashinfo.com.
- "Stop Those Mid-Air Collisions" (PDF). Deseret News (Salt Lake City). April 22, 1958. p. 18.
- Accident description for May 20, 1958 mid-air between Capital Airlines Vickers Viscount and Air National Guard Lockheed T-33 over Brunswick, MD at the Aviation Safety Network
- "Urgent: Air Space Positive Control". FLIGHT (Iliffe and Sons) 73 (2575): 753. May 30, 1958.
- "Need For Expanded Air Controls Cited" (PDF). Lakeland Ledger. AP. August 20, 1958. p. 3.
- "The Federal Aviation Administration and Its Predecessor Agencies". centennialofflight.net. U.S. Centennial of Flight Commission.
- Hanson, Robert A. (January 1, 2002). "Air Combat U". Air & Space Smithsonian.
- "Official USAF F-100 accident rate table]" (PDF). Air Force Safety Center. U.S. Department of Defense.
- "335 F.2d 379 para. 1". July 24, 1964. "These appeals are from judgments in thirty-one cases arising out of a mid-air collision between a DC-7 propeller driven commercial airliner owned and operated by United Air Lines (hereinafter "United") and an F-100F United States Air Force jet fighter."
- "282 F.2d 428 para. 7". July 28, 1960. "On September 24, 1958, United Airlines, Inc. filed a complaint against the United States, No. C. A. 2043 in the United States District Court for the District of Delaware, based on the Federal Tort Claims Act, 28 U.S.C. § 1346(b), alleging that the United States through its agents in the United States Air Force so negligently operated a F-100F Super Saber Jet Fighter airplane in the vicinity of Las Vegas, Nevada, that a Douglas DC-7 airplane owned by the plaintiff collided with the Air Force jet destroying the plaintiff's airplane and causing very substantial damage to the plaintiff."
- "Airline Sues U.S. in Plane Crash" (PDF). Milwaukee Sentinel. AP. September 25, 1958. p. 7, part 2.
- "351 F.2d 354 note 4". September 30, 1965. "In the District of Delaware, United Air Lines, Inc., sued the United States to recover the value of its airplane. The court there held neither crew negligent for failure to see and avoid, but held the United States liable because of other negligence. The record indicates that the Delaware case was settled without appeal. By agreement of the parties, much of the record in this case was made in the trials of the previous cases."
- "Crash Suit Settled for $1.45 million" (PDF). Toledo Blade. AP. December 18, 1962. p. 6.
- "Families Get $343,200 in Jet Collision Case" (PDF). St. Petersburg Times. UPI. January 9, 1964. p. 12-A.
- "351 F.2d 354 para. 7". September 30, 1965. "The United States argues that under the stipulated facts the F-100F was converging on the DC-7 head-on under the KRAM procedure at a 5 degree angle of descent, and the members of the (DC-7) crew were negligent as a matter of law in not observing and avoiding it. With this contention we do not agree."
- "351 F.2d 354 para. 15". September 30, 1965. "The plaintiffs, in their cross-appeals, insist that the awards made by the trial court are inadequate and result from wrongful mathematical calculations and deductions. We are satisfied that considering the record as a whole, the judgments were not only adequate, but generous"
- Boone, Jim. "Carole Lombard Crash Site". birdandhike.com.
- Bates, Warren (November 15, 1999). "Hunt for Lost F-27". Las Vegas Review-Journal. Archived from the original on 2003-05-08.
- "Memorial sought for fighter, airliner collision". Air Force Times. AP. April 22, 2008.
- Cited legal decisions
- United States, Petitioner v. Honorable Caleb M. Wright, Respondent, 282 F.2d 428 (U.S. Court of Appeals Third circuit July 28, 1960). bulk.resource.org
- United Airlines v. Wiener, 335 F.2d 379 (U.S. Court of Appeals Ninth Circuit June 24, 1964). openjurist.org
- United States v. Sommers, 351 F.2d 354 (U.S. Court of Appeals Tenth Circuit September 30, 1965). openjurist.org
- Rochester, Stuart I. (1976). Takeoff at mid-century : Federal civil aviation policy in the Eisenhower years, 1953-1961. Washington, D.C.: U.S. Dept. of Transportation, Federal Aviation Administration. ASIN B002YNRUXG. babel.hathitrust.org
- Contemporary newspaper articles selected from the Google News archives:
- "Death Of Plane's Crew Leaves 10 Fatherless" (PDF). Deseret News (Salt Lake City). INS. April 22, 1958. p. 1.
- Madsen, Reed (April 22, 1958). "Blackened Pits, Strewn Parts Mark Death Site" (PDF). Deseret News (Salt Lake City). p. 1.
- McClure, Hal; Torgerson, Dial (April 25, 1958). "Series of Air Crashes Point to New Dangers" (PDF). Gadsden Times. AP. p. 12.
- "Air Congestion Map" (PDF). Lakeland Ledger. AP. April 25, 1958. p. 1.
- Zielke, George (May 4, 1958). "'We Are Far Behind' In Air-Traffic Control" (PDF). Toledo Blade. pp. 1–2, section 2.
- Wilson, Victor (May 6, 1958). "Near Collisions Under Probe" (PDF). Tuscaloosa News. Herald Tribune Service. p. 4.
- "April 21, 1958, United Air Lines / USAF, Douglas DC-7 (N6328C) / North American F-100F (56-3755) Mid-Air Collision near Las Vegas, NV". lostflights.com. - extensive photo gallery
- "Aerial view of the DC-7 crash site from 1958". baaa-acro.com.
- "Aerial view of the DC-7 crash site today". Bing Maps.
- "Ground views of the DC-7 crash site from 1958". lostbirds.com.
- "Unofficial early attempt to reconstruct the collision using scale models". LIFE. May 1958. (collision angles are inaccurate)