View source for 1956 Grand Canyon mid-air collision

{{Short description|Mid-air collision on June 30, 1956 over the Grand Canyon}}
{{Redirect|Grand Canyon mid-air collision|the 1986 accident|1986 Grand Canyon mid-air collision}}
{{Use mdy dates|date=August 2023}}
{{Infobox Aircraft accident
| name            = 1956 Grand Canyon mid-air collision<br />{{nobold|{{small|United Airlines Flight 718{{·}}TWA Flight 2}}}}
| image           = 1956 Grand Canyon mid-air collision.png
| image_upright   = 1.2
| caption         = Illustration of the collision
| date            = June 30, 1956
| type            = [[Mid-air collision]]<br />due to inadequate [[Air traffic control|ATC]] system
| occurrence_type = Accident
| site            = [[Grand Canyon]], [[Arizona]], U.S.
| total_fatalities = 128
| total_survivors = 0
| plane1_image    = UAL DC-7 (cropped).jpg
| plane1_image_upright = 1.2
| plane1_caption  = A United Airlines DC-7, similar to the aircraft involved
| plane1_type     = [[Douglas DC-7|Douglas DC-7 Mainliner]]
| plane1_operator = [[United Airlines]]
| plane1_tailnum  = {{Airreg|N|6324C}}
| plane1_name     = ''Mainliner Vancouver''
| plane1_origin   = [[Los Angeles International Airport|Los Angeles Int'l Airport]]
| plane1_destination = [[Chicago Midway Airport]]
| plane1_passengers = 53
| plane1_crew     = 5
| plane1_fatalities = 58
| plane1_occupants = 58
| plane1_survivors = 0
| plane2_image    = N6902C Star of the Seine.jpg
| plane2_image_upright = 1.2
| plane2_caption  = The Lockheed L-1049A Super Constellation involved  <!---->
| plane2_type     = [[Lockheed L-1049A Super Constellation]]
| plane2_operator = [[Trans World Airlines]]
| plane2_tailnum  = {{Airreg|N|6902C}}
| plane2_name     = ''Star of the Seine''
| plane2_origin   = [[Los Angeles Int'l Airport]]
| plane2_destination = [[Kansas City Downtown Airport]]
| plane2_passengers = 64
| plane2_crew     = 6
| plane2_fatalities = 70
| plane2_occupants = 70
| plane2_survivors = 0
}}

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The '''Grand Canyon mid-air collision''' occurred in the [[Western United States|western]] [[United States]] on June 30, 1956, when a [[United Airlines]] [[Douglas DC-7]] struck a [[Trans World Airlines]] [[Lockheed L-1049 Super Constellation]] over [[Grand Canyon National Park]], [[Arizona]]. The first plane fell into the [[canyon]] while the other slammed into a rock face. All 128 on board both airplanes perished, making it the first commercial airline incident to exceed one hundred fatalities. The airplanes had departed [[Los Angeles International Airport]] minutes apart from each other and headed for [[Chicago]] and [[Kansas City, Missouri|Kansas City]], respectively.
The collision took place in uncontrolled airspace, where it was the pilots' responsibility to maintain [[separation (aeronautics)|separation]] ("see and be seen"). This highlighted the antiquated state of air traffic control, which became the focus of major aviation reforms.

==Flight history==

'''Trans World Airlines Flight 2''', a [[Lockheed L-1049 Super Constellation]] named ''Star of the Seine'', with [[pilot in command|Captain]] Jack Gandy (age 41), [[First officer (aeronautics)|First Officer]] James Ritner (31), and [[Flight Engineer]] Forrest Breyfogle (37), departed Los Angeles on Saturday, June 30, 1956, at 9:01&nbsp;am PST with 64 passengers (including 11 TWA off-duty employees on free tickets) and six crew members (including two [[flight attendant]]s and an off-duty flight engineer), and headed to [[Charles B. Wheeler Downtown Airport|Kansas City Downtown Airport]], 31 minutes behind schedule. Flight 2, initially flying under [[instrument flight rules]] (IFR), climbed to an authorized [[Metres above sea level|altitude]] of {{convert|19000|ft}} and stayed in controlled airspace as far as [[Daggett, California]]. At Daggett, Captain Gandy turned right to a heading of 059 degrees magnetic, toward the [[low-frequency radio range|radio range]] near [[Trinidad, Colorado]].<ref name="ReferenceB">CAB Docket 320, File 1, History of Flights, Section 1, issued 1957/04/17</ref> The Constellation was now "off airways", otherwise known as flying in [[uncontrolled airspace]].<ref name="ReferenceA">CAB Docket 320, File 1, History of Flights, Section 2, issued 1957/04/17</ref>

'''United Airlines Flight 718''', a [[Douglas DC-7]] named ''Mainliner Vancouver'', was piloted by Captain Robert "Bob" Shirley (age 48), First Officer Robert Harms (36), and Flight Engineer Girardo "Gerard" Fiore (39). They departed Los Angeles at 9:04&nbsp;am PST with 53 passengers and 5 crew members aboard (including two flight attendants), bound for Chicago's [[Chicago Midway Airport|Midway Airport]]. Climbing to an authorized altitude of {{convert|21000|ft}}, Captain Shirley flew under IFR in [[controlled airspace]] to a point<ref group="note">The "Palm Springs" intersection was at about 33.92N 116.28W.</ref> northeast of [[Palm Springs, California]], where he turned left toward a radio beacon near [[Needles, California]], after which his flight plan was direct to Durango in southwestern Colorado.<ref group="note">The report says their flight plan was Needles direct to Durango, but it's unclear what "Durango" means. There never was an [[low-frequency radio range|LF/MF radio range]] there, and the [[VHF omnidirectional range|VOR]] wasn't there in 1956. (There was an AM radio station.)</ref> United's DC-7, though still under IFR, was now, like TWA's Constellation, en route in uncontrolled airspace.

Shortly after takeoff TWA's Captain Gandy requested permission to climb to 21,000&nbsp;feet to avoid [[cumulonimbus cloud|thunderheads]] that were forming near his flight path. As was the practice at the time, his request had to be relayed by a TWA [[flight dispatcher]] to air traffic control (ATC), as neither crew was in direct contact with ATC after departure. ATC denied the request; the two airliners would soon be reentering controlled airspace (the Red 15 airway running southeast from Las Vegas) and ATC had no way to provide the horizontal separation required between two aircraft at the same altitude.

Captain Gandy then requested "1,000 on top" clearance (flying {{convert|1000|ft|m}} above the clouds, and thus in [[visual meteorological conditions]]). This was approved by ATC, and meant that the Constellation was still under IFR but free of separation restrictions normally applied by ATC. It transferred to Gandy and Ritner the responsibility for maintaining safe separation from other aircraft, on the principle then termed "see and be seen" (more recently "see and avoid").

This division of responsibilities between aircrew and ATC is especially useful when two aircraft are transitioning to or from an airfield approach when VFR conditions exist above cloud layers.<ref>{{cite web |title=IFR Rules and Procedures&nbsp;– En Rouite and Holds, Langley Flying School |url=http://www.langleyflyingschool.com/Pages/IFR%20Groundschool--IFR%20Rules%20and%20Procedures--En%20Route%20and%20Holds.html |archive-url=https://web.archive.org/web/20130703152806/http://www.langleyflyingschool.com/Pages/IFR%20Groundschool--IFR%20Rules%20and%20Procedures--En%20Route%20and%20Holds.html |archive-date=2013-07-03 |url-status=live |access-date=2013-07-02 }}</ref> It is less common en route.

Upon receiving "1,000 on top" clearance, Captain Gandy increased his altitude to {{convert|21,000|ft|m}}.<ref name="ReferenceB" /> Both crews were then at this altitude, and both had estimated that they would cross the [[Painted Desert (Arizona)|Painted Desert]] line at about 10:31 am Pacific time.<ref>CAB Docket 320, File 1, History of Flights, Section 1, Paragraph 5, issued 1957/04/17</ref><ref>CAB Docket 320, File 1, History of Flights, Section 2, Paragraph 5, issued 1957/04/17</ref> The Painted Desert line was about {{convert|200|mi|spell=in}} long, running between the [[VHF omnidirectional range|VOR]]s at [[Bryce Canyon]], Utah, and [[Winslow, Arizona|Winslow]], Arizona, at an angle of 335 degrees relative to [[true north]] – wholly outside of controlled air space. Owing to the different headings taken by the two planes, TWA's crossing of the Painted Desert line, assuming no further course changes, would be at a 13-degree angle relative to that of the United flight, with the Constellation to the left of the DC-7.

As the two aircraft approached the Grand Canyon, at the same altitude and nearly the same speed, the pilots were likely maneuvering around towering cumulus clouds. (The Constellation's clearance required it to stay in clear air – and ''above'' cloud.) As they were maneuvering near the canyon, it is believed the planes passed the same cloud on opposite sides.<ref>''Blind Trust'', by John J. Nance, William Morrow & Co., Inc. (US), 1986, {{ISBN|0-688-05360-2}}, pp. 90–92</ref>

== Collision ==
[[File:Severed tail of TWA Flight 2.jpg|thumb|The severed [[empennage|tail assembly]] of the TWA Constellation with the unique three [[vertical stabilizer]]s missing, as photographed by [[National Park Service|park rangers]] during the [[Civil Aeronautics Board|CAB]] investigation]]
At about 10:30&nbsp;am, the two aircraft collided over the canyon at an angle of about 25 degrees.<ref>CAB Docket 320, File 1, Analysis, Paragraph 5, issued 1957/04/17</ref>&nbsp; Post-crash analysis determined that the United DC-7 was banking to the right and pitching down at the time of the collision, suggesting that one or possibly both of the United pilots spotted the TWA Constellation and attempted evasive action.<ref>CAB Docket 320, File 1, Analysis, Paragraph 6, issued 1957/04/17</ref>

The DC-7's upraised left wing clipped the top of the Constellation's [[vertical stabilizer]] and struck the [[fuselage]] immediately ahead of the stabilizer's base, causing the [[empennage|tail assembly]] to break away from the rest of the [[airframe]].{{Cn|date=May 2024}} The [[propeller (aircraft)|propeller]] on the DC-7's left outboard, or number one [[aircraft engine|engine]], concurrently chopped a series of gashes into the bottom of the Constellation's fuselage. [[Explosive decompression]] would have instantaneously occurred from the damage, a theory substantiated by light debris, such as cabin furnishings and personal effects, being scattered over a large area.
[[File:Chuar & Temple Buttes (TWA & UAL).jpg|left|thumb|The [[Grand Canyon]] sites of the two aircraft impacts.]]
The separation of the tail assembly from the Constellation resulted in immediate loss of control, causing the aircraft to enter a near-vertical, [[terminal velocity]] dive.{{Cn|date=May 2024}} Plunging into the Grand Canyon at an estimated speed of more than {{convert|700|ft/s|kn mph km/h}}, the Constellation slammed into the north slope of a ravine on the northeast slope of [[Temple Butte]] and disintegrated on impact, instantly killing all aboard. An intense fire, fueled by [[aviation gasoline]], ensued. The severed tail assembly, badly battered but still somewhat recognizable, came to rest nearby.

The DC-7's left wing to the left of the number one engine was mangled by the impact and was no longer capable of producing substantial [[lift (force)|lift]]. The engine had been severely damaged as well, and the combined loss of lift and propulsion left the crippled airliner in a rapidly descending left spiral from which recovery was impossible.<ref name="ReferenceA" /> The ''Mainliner'' collided with the south side [[cliff]] of [[Chuar Butte]] and disintegrated, instantly killing all aboard.

==Aftermath==

===Search and recovery===
The airspace over the canyon was not under any type of [[radar]] observation and there were no [[Emergency position-indicating radiobeacon station|homing beacons]], [[cockpit voice recorder]]s, or [[flight data recorder]]s aboard either aircraft. The last position reports received from the flights did not reflect their locations at the time of the collision. Also, there were no credible witnesses to the collision itself or the subsequent crashes.

The only immediate indication of trouble was when United company radio operators in [[Salt Lake City, Utah|Salt Lake City]] and [[San Francisco]] heard a garbled transmission from Flight 718, the last from either aircraft.{{Cn|date=May 2024}} [[Civil Aeronautics Board]] (CAB) [[accident investigation]] engineers later deciphered the transmission – which had been preserved on [[magnetic tape]] – as the voice of co-pilot Robert Harms declaring, "Salt Lake, [ah], 718&nbsp;... we are going in!" The shrill voice of Captain Shirley was heard in the background as, presumably futilely struggling with the controls, he implored the airplane to "[Pull] up! [Pull] up!" (bracketed words were inferred by investigators from the context and circumstances in which they were uttered).<ref>CAB Docket 320, File 1, Investigation, Paragraphs 41–43, issued 1957/04/17</ref>

After neither flight reported their current position for some time, the two aircraft were declared to be missing, and search and rescue procedures started. The wreckage was first seen late in the day near the confluence of the [[Colorado River|Colorado]] and [[Little Colorado River]]s by Henry and Palen Hudgin, two brothers who operated [[Grand Canyon Airlines]], a small air taxi service.<ref name="Blind Trust 1986, pp. 96-97">''Blind Trust'', by John J. Nance, William Morrow & Co., Inc. (US), 1986, {{ISBN|0-688-05360-2}}, pp. 96–97</ref> During a trip earlier in the day, Palen had noted dense black smoke rising near [[Temple Butte]], the crash site of the Constellation, but had dismissed it as brush set ablaze by [[lightning]].
[[File:TWAGrandCanyonCrashMemorial2.jpg|thumb|left|Burial site and memorial for the TWA passengers and crew, Citizens Cemetery, Flagstaff, Arizona. [https://books.google.com/books?id=cUgEAAAAMBAJ&pg=PA34 1956 funeral photo from ''Life'' magazine].]]

However, upon hearing of the missing airliners, Palen decided that what he had seen might have been smoke from a post-crash fire. He and his brother flew a light aircraft (a [[Piper Tri-Pacer]]) deep into the canyon and searched near the location of the smoke. The Constellation's [[empennage]] was found, and the brothers reported their findings to authorities. The following day, the two men pinpointed the wreckage of the DC-7. Numerous [[helicopter]] missions were subsequently flown down to the crash sites to find and attempt to identify victims, as well as recover wreckage for accident analysis, a difficult and dangerous process due to the rugged terrain and unpredictable [[air current]]s.<ref>CAB Docket 320, File 1, Investigation, Paragraphs 2–3, issued 1957/04/17</ref>
[[File:TWAGrandCanyonCrashMemorial.jpg|thumb|right|Close-up of plaque honoring TWA passengers and crew, Citizens Cemetery]]

The airlines hired the [[Rega (air rescue)|Swiss Air-Rescue]]<ref>{{cite web|url=https://www.rega.ch/en/about-us/history/1946-1959.aspx |title=The beginnings of air-rescue 1946–1959 |archiveurl=https://web.archive.org/web/20190727170916/https://www.rega.ch/en/about-us/history/1946-1959.aspx |archivedate=2019-07-27 |publisher=[[Rega (air rescue)|Rega]]}}</ref> and some Swiss mountain climbers to go to the scene where the aircraft fuselages had crashed. They were to gather the remains of the passengers and their personal effects. This was given considerable publicity in U.S. news releases at the time because of the ruggedness of the terrain where the fuselages came to rest.{{citation needed|date=September 2018}}

Owing to the great violence of the impacts, no bodies were recovered intact and positive identification of most of the remains was not possible. On July 9, 1956, a mass funeral for the victims of TWA Flight 2 was held,<ref>{{cite web|url=https://www.nytimes.com/1956/07/11/archives/29-dc7-dead-identified-mass-services-to-be-held-for-29-others-in.html|title=29 DC-7 Dead Identified; Mass Services to Be Held for 29 Others in Canyon Crash|newspaper=[[The New York Times]]|date=1956-07-11|page=1}}</ref> at the canyon's south rim.{{citation needed|date=July 2023}} Twenty-nine unidentified victims of the United flight were interred in four coffins at the [[Grand Canyon Pioneer Cemetery]]. Sixty-six of the seventy TWA passengers and crew are buried in a mass grave at Citizens Cemetery in [[Flagstaff, Arizona]]. A number of years elapsed following this accident before most of the wreckage was removed from the canyon. Some pieces of the aircraft still remain at the crash sites.

===Investigation===
The investigation of this accident, led by [[Jack Parshall]], was particularly challenging due to the remoteness and [[topography]] of the crash sites, as well as the extent of the destruction of the two airliners and the lack of real-time flight data as might be derived from a modern flight data recorder. Despite the considerable difficulties, CAB experts were able to determine with a remarkable degree of certainty what had transpired and, in their report, issued the following statement as probable cause for the accident:<ref name=ca320f1>CAB Docket 320, File 1, Probable Cause, issued 1957/04/17</ref>

{{blockquote|The Board determines that the probable cause of this mid-air collision was that the pilots did not see each other in time to avoid the collision. It is not possible to determine why the pilots did not see each other, but the evidence suggests that it resulted from any one or a combination of the following factors: Intervening clouds reducing time for visual separation, visual limitations due to cockpit visibility, and preoccupation with normal cockpit duties, preoccupation with matters unrelated to cockpit duties such as attempting to provide the passengers with a more scenic view of the Grand Canyon area, physiological limits to human vision reducing the time opportunity to see and avoid the other aircraft, or insufficiency of en route air traffic advisory information due to inadequacy of facilities and lack of personnel in air traffic control.}}

In the report, weather and [[airworthiness]] of the two planes were thought to have played no role in the accident. Lacking [[Credible witness|credible eyewitnesses]] and with some uncertainty regarding high altitude visibility at the time of the collision, it was not possible to determine conclusively how much opportunity was available for the TWA and United pilots to see and avoid each other.<ref name=ca320f1/>

Neither flight crew was specifically implicated in the CAB's finding of probable cause, although the decision by TWA's Captain Gandy to cancel his IFR flight plan and fly "1,000 on top" was the likely catalyst for the accident. Also worth noting was that the investigation itself was thorough in all respects, but the final report focused on technical issues and largely ignored contributory [[Aviation safety#Human factors|human factors]], such as why the airlines permitted their pilots to execute maneuvers solely intended to improve the passengers' view of the canyon. It would not be until the late 1970s that human factors would be as thoroughly investigated as technical matters following aerial mishaps.<ref name="Blind Trust 1986, pp. 96-97"/>

During the investigation, [[Mel Hunter|Milford "Mel" Hunter]], a scientific and technical illustrator with [[Life (magazine)|''Life'' magazine]], was given early and unrestricted access to the CAB's data and preliminary findings, enabling him to produce an illustration of what likely occurred at the moment of the collision. Hunter's finely detailed [[gouache]] painting first appeared in ''Life''{{'s}} April 29, 1957, issue<ref name="life1957">{{cite magazine |url=https://books.google.com/books?id=PEkEAAAAMBAJ&pg=PA151 |title=Air Mystery is Solved |first=Mary H. |last=Cadwalader | magazine=[[Life (magazine)|Life]] |date=April 29, 1957 |pages=151–164}}</ref> and was subsequently included in David Gero's 1996 edition of ''Aviation Disasters II''.

In a letter to Gero in 1995, Hunter wrote:<ref group="note">As related by Susan Smith-Hunter, Mel Hunter's widow.</ref>{{citation needed|date=October 2013}}

{{blockquote|I was able to plot the two intersecting flight paths and the fact that both planes were in each other's blind spot. I remember showing that the descending aircraft's propellers chewed a series of gashes along the fuselage top of the ascending aircraft. I did a lot of this type of factual re-creation for ''Life''. They were always extremely tough to piece together to the satisfaction of all the editors, art directors and assorted researchers who were assigned to such projects. But, it was extremely interesting work.}}

Hunter's recollection of his illustration was not completely accurate. The painting showed the DC-7 below the Constellation, with the former's number one engine beneath the latter's fuselage, which disagreed with the CAB technical findings.<ref name="life1957"/><ref>{{cite web |url=http://lostflights.smugmug.com/gallery/4906723_y8cPU/2/305765767_2uEnQ/Large |title=June 30, 1956: Trans World Airlines / United Air Lines, Lockheed L-1049 (N6902C) / Douglas DC-7 (N6324C) Mid-Air Collision, Grand Canyon, AZ |website=lostflights.com}}</ref>

===Catalyst for change===
{{More citations needed section|date=August 2009}}
At 128 fatalities, the Grand Canyon collision became the deadliest U.S. commercial airline disaster and deadliest air crash on U.S. soil of any kind, surpassing [[United Airlines Flight 409]] the year before.<ref>{{Cite web |last=Jones |first=Tia |date=2014-05-02 |title=Grand Canyon Collision Declared a National Historic Landmark |url=https://explorethecanyon.com/grand-canyon-collision-declared-a-national-historic-landmark/ |access-date=2023-09-11 |website=Grand Canyon Visitor Center |language=en-US}}</ref> It was surpassed in both respects on December 16, 1960, by the [[1960 New York mid-air collision]]. Coincidentally, the collision also involved United and TWA and saw 128 deaths in the two aircraft (in addition to 6 deaths on ground). However, it is still the deadliest aviation disaster in the state of Arizona.

The accident was covered by the press worldwide, and as the story unfolded, the public learned of the primitive nature of air traffic control (ATC) and how little was being done to modernize it. The [[air traffic controller]] who had cleared TWA to "1,000 on top" was severely criticized as he had not advised Captains Gandy and Shirley about the potential for a traffic conflict following the clearance, even though he must have known of the possibility. The controller was publicly blamed for the accident by both airlines and was vilified in the press, but he was cleared of any wrongdoing. As Charles Carmody (the then-assistant ATC director) testified during the investigation, neither flight was legally under the control of ATC when they collided, as both were "off airways." The controller was not required to issue a traffic conflict advisory to either pilot. According to the CAB accident investigation final report, page 8, the en-route controller relayed a traffic advisory regarding United 718 to TWA's ground radio operator: "ATC clears TWA 2, maintain at least 1,000 on top. Advise TWA 2 his traffic is United 718, direct Durango, estimating Needles at 0957." The TWA operator testified that Captain Gandy acknowledged the information on the United flight as "traffic received."<ref>{{cite web |url=http://lessonslearned.faa.gov/UAL718/CAB_accident_report.pdf |title=Civil Aeronautics Board Accident Investigation Report |publisher=[[Federal Aviation Administration]] |url-status=dead |archive-url=https://web.archive.org/web/20150220195809/http://lessonslearned.faa.gov/UAL718/CAB_accident_report.pdf |archive-date=February 20, 2015 |access-date=March 20, 2014 }}</ref>

The accident was particularly alarming in that public confidence in [[air travel]] had increased during the 1950s with the introduction of new airliners like the [[Lockheed L-1049 Super Constellation|Super Constellation]], [[Douglas DC-7]], and [[Boeing 377|Boeing Stratocruiser]]. Travel by air had become routine for large corporations, and [[Tourism|vacationers]] often considered flying instead of traveling by [[railroad|train]]. At the time, a [[congressional committee]] was reviewing domestic air travel, as there was growing concern over the number of accidents. However, little progress was being made and the state of ATC at the time of the Grand Canyon accident reflected the methods of the 1930s.

As [[near miss (safety)|near-misses]] and mid-air collisions continued, the public demanded action. Often-contentious [[congressional hearing]]s followed, and in 1957, increased funding was allocated to modernize ATC, hire and train more air traffic controllers, and procure much-needed radar – initially military surplus equipment.

However, control of American airspace continued to be split between the [[military]] and the [[United States government role in civil aviation#Civil Aeronautics Authority|Civil Aeronautics Administration]] (CAA, the [[federal government of the United States|federal agency]] in charge of air traffic control at the time). The CAA had no authority over military flights, which could enter controlled airspace with no warning to other traffic. The result was a series of near-misses and collisions involving civil and [[military aircraft]], the latter often flying at much higher speeds than the former. For example, in 1958, the collision of [[United Airlines Flight 736]] flying "on-airways" and an [[F-100 Super Sabre]] fighter jet near [[Las Vegas, Nevada]], resulted in 49 fatalities.

Again, action was demanded. After more hearings, the [[Federal Aviation Act of 1958]] was passed, dissolving the CAA and creating the [[Federal Aviation Agency]] (FAA, later renamed the [[Federal Aviation Administration]] in 1966). The FAA was given total authority over American airspace, including military activity, and as procedures and ATC facilities were modernized, mid-air collisions gradually became less frequent.

In 1960, a jury in Kansas City, in a judgment against United Airlines, awarded the estate of Jack S. Gandy, the pilot of the TWA flight, $64,000 ({{Inflation|US|64000|1960|fmt=eq|r=-4}}), and the estate of James H. Ritner, the co-pilot, $45,000 ({{Inflation|US|45000|1960|fmt=eq|r=-4}}).<ref name="nytimes0924">{{cite news | url = https://timesmachine.nytimes.com/timesmachine/1960/09/24/99806302.html?pageNumber=5 | work = The New York Times | date = 24 September 1960 | accessdate = 18 April 2023 | agency = Associated Press | page = 5 |title = Air Crash Damages Set }}</ref>

===National Historic Landmark===
{{Infobox NRHP | name =1956 Grand Canyon mid-air collision
  | nrhp_type =nhl
  | image = 1956 Grand Canyon mid-air collision NRHP plaque.jpg
  | caption =
  | location = [[Coconino County, Arizona]]
  | nearest_city=
  | coordinates = {{coord|36|10|30|N|111|50|00|W|region:US-AZ_type:landmark_scale:50000|display=inline,title}}
| locmapin =
  | area =
  | built =
  | architect=
  | architecture=
  | added = April 22, 2014
  | governing_body =
  | refnum=14000280
}}
On April 22, 2014, the site of the crash was declared a [[National Historic Landmark]],<ref>{{cite news|url=https://www.nps.gov/nhl/find/statelists/az/AZ.pdf | title=National Historic Landmarks in Arizona| agency=[[National Park Service]] | access-date=July 7, 2017}}</ref> making it the first landmark for an event that happened in the air.<ref>{{cite web | url=http://www.nps.gov/nhl/news/LC/spring2011/GrandCanyonREDACTED.pdf | title=1956 Grand Canyon TWA-United Airlines Aviation Accident Site | publisher=[[National Park Service]] | access-date=July 7, 2017}}</ref> The location, in a remote portion of the canyon accessible only to hikers, has been closed to the public since the 1950s.<ref>{{cite news | title=The Site of a 1950s Plane Crash Just Became a National Landmark |url=https://www.theatlantic.com/technology/archive/2014/04/the-site-of-a-1950s-plane-crash-just-became-a-national-landmark/361183/ | work=[[The Atlantic]] | date=April 24, 2014 | first=Adrienne | last=LaFrance | access-date=April 28, 2014}}</ref><ref name="Grady30Apr14">{{cite news|url = http://www.avweb.com/avwebflash/news/Historic-Plane-Wreck-Site-Protected221938-1.html|title = Historic Plane Wreck Site Protected|access-date = May 3, 2014|last = Grady|first = Mary|date = April 30, 2014| work = AVweb}}</ref>

==Dramatizations==
In 2006, the story of this disaster was covered in the third season of the History Channel program ''[[UFO Files]]''. The episode, entitled "Black Box UFO Secrets", contained the Universal Newsreel footage of the accident narrated by [[Ed Herlihy]].<ref name="IMDB: UFO Files (Season 3: Black Box UFO Secrets)">{{cite web |url=https://www.imdb.com/title/tt1713917/ |title=The Internet Movie Database: UFO Files (Season 3: Black Box UFO Secrets) |work=The Internet Movie Database}}</ref>

In 2010, the story of the disaster, along with other mid-air collisions, was featured on the eighth season of the [[National Geographic Channel]] show ''[[Mayday (Canadian TV series)|Mayday]]'' (also known as ''Air Emergency'' and ''Air Crash Investigation''). The special episode is entitled "System Breakdown".<ref>{{Citation |title=Air Crash Investigation Season 8 |url=http://archive.org/details/aci8_20230105 |access-date=2024-03-05}}</ref> In 2013, an episode from the twelfth season, entitled "Grand Canyon Disaster", also featured this accident.<ref>{{Citation |title=Mayday – Air Crash Investigation (S01-S22) |url=http://archive.org/details/mayday-aci |access-date=2024-02-16}}</ref>

It is featured in season 1, episode 5, of the TV show ''[[Why Planes Crash]]'', in an episode called "Collision Course".

In 2015, the first season of ''[[Mysteries at the National Parks]]'' on the Travel Channel, in the series' seventh episode entitled, "Portal To The Underworld" the crash was also featured and was mentioned as being a "supernatural event."
In 2014, the Smithsonian channel show "Air Disasters" episode 4 season 6 covered the event and investigation in episode "Grand Canyon".

==See also==
{{Portal bar|Arizona|Aviation|1950s}}
* [[Aeroméxico Flight 498]]
* [[1996 Charkhi Dadri mid-air collision]]
* [[Free flight (air traffic control)]]
* [[Gol Transportes Aéreos Flight 1907]]
* [[1986 Grand Canyon mid-air collision]], another airliner involved in a mid-air collision over the Grand Canyon
* [[Hughes Airwest Flight 706]]
* [[2001 Japan Airlines mid-air incident]]
* [[List of National Historic Landmarks in Arizona]]
* [[National Register of Historic Places listings in Coconino County, Arizona]]
* [[1960 New York mid-air collision]], which also involved aircraft from [[United Airlines]] and [[Trans World Airlines]]
* [[Pacific Southwest Airlines Flight 182]]
* [[1922 Picardie mid-air collision]]
* [[2002 Überlingen mid-air collision]]
* [[1976 Zagreb mid-air collision]]

==Notes==
{{Reflist|group="note"}}

==References==
{{Reflist}}

==Sources==
* Civil Aeronautics Board Official Report, Docket 320, File 1, issued on April 17, 1957
* ''Air Disaster, Vol. 4: The Propeller Era'', by [[Macarthur Job]], Aerospace Publications Pty. Ltd. (Australia), 2001. {{ISBN|1-875671-48-X}}
* ''Blind Trust'', by [[John J. Nance]], William Morrow & Co., Inc. (US), 1986, {{ISBN|0-688-05360-2}}

== External links ==
{{Commons category|1956 Grand Canyon mid-air collision}}
* {{cite web |url=http://lessonslearned.faa.gov/UAL718/CAB_accident_report.pdf |title=Civil Aeronautics Board Accident Investigation Report |publisher=[[Federal Aviation Administration]] |url-status=dead |archive-url=https://web.archive.org/web/20150220195809/http://lessonslearned.faa.gov/UAL718/CAB_accident_report.pdf |archive-date=2015-02-20 }} – [https://rosap.ntl.bts.gov/view/dot/33556 Alternate URL] with [https://rosap.ntl.bts.gov/view/dot/33556/dot_33556_DS1.pdf PDF]
* {{cite web | url= http://lessonslearned.faa.gov/UAL718/Flightpaths_pop_up.htm | title= TWA Flight 2 and UAL Flight 718 Flight Plans | publisher= Federal Aviation Administration | access-date= 2014-03-20 | archive-url= https://web.archive.org/web/20140322122602/http://lessonslearned.faa.gov/UAL718/Flightpaths_pop_up.htm | archive-date= 2014-03-22 | url-status= dead }}
* {{cite magazine| url= https://books.google.com/books?id=PEkEAAAAMBAJ&pg=PA151 | title= Air Mystery is Solved| first= Mary H. |last= Cadwalader| magazine= [[Life (magazine)|Life]] | date= April 29, 1957 |pages= 151–164}}
* [http://www.twaseniorsclub.org/memories/contrails/tragedygrandcanyonTW-UA.html Lessons from Tragedy Over the Grand Canyon] by Jon Proctor
* [http://archives.obs-us.com/obs/english/books/rawlins/moths/stumble/9.html ''Flying Blind''] by Gregory Rawlins
* [http://www.aircraftarchaeology.com/twaunited.html TWA and United collision over Grand Canyon] Arizona Aircraft Archaeology
* [https://www.youtube.com/watch?v=c2uyLMAWZ6g What Caused The "Worst Accident In The History" Of Commercial Aviation?] Mayday: Air Disaster – YouTube Channel

{{Lockheed Constellation family}}
{{Aviation accidents and incidents in 1956}}
{{Aviation accidents and incidents in the United States in the 1950s}}
{{United Continental Holdings}}
{{TWA}}
{{Grand Canyon}}
{{NRHP in Grand Canyon NP}}

{{DEFAULTSORT:Grand Canyon mid-air collision, 1956}}
[[Category:Airliner accidents and incidents in Arizona]]
[[Category:Aviation accidents and incidents in the United States in 1956]]
[[Category:Events in Coconino County, Arizona]]
[[Category:Trans World Airlines accidents and incidents]]
[[Category:United Airlines accidents and incidents]]
[[Category:1956 in Arizona]]
[[Category:Disasters in Arizona]]
[[Category:Grand Canyon]]
[[Category:Accidents and incidents involving the Douglas DC-7]]
[[Category:Accidents and incidents involving the Lockheed Constellation]]
[[Category:Airliner accidents and incidents caused by pilot error]]
[[Category:Mid-air collisions involving airliners]]
[[Category:Mid-air collisions]]
[[Category:National Historic Landmarks in Arizona]]
[[Category:National Register of Historic Places in Coconino County, Arizona]]
[[Category:June 1956 events in the United States]]
[[Category:1956 in the United States]]