Greatest air tragedy of its time in U.S. aviation.  On the morning of Saturday, June 30, 1956, United Flight 718 collided with TWA Flight 2 over the eastern end of the Grand Canyon.  Since the accident involved two of the largest commercial aircraft then in service--a Lockheed Super Constellation, and a Douglas DC-7--it resulted in the greatest loss of life, by far, in any accident of the time.  The enormity of the loss gave impetus to a major improvement in air traffic control with the formation of the Federal Aviation Administration and the widespread use of collision avoidance radar on commercial aircraft. 

TWA's Super Constellation.  The  Constellation changed the face of commercial aviation.  In the 1930's, Howard Hughes, a major shareholder of TWA, wanted a plane that would fly higher, faster, farther, and carry more passengers than existing passenger aircraft.  He turned to Lockheed with his extraordinary request and the stipulation that the project be kept secret.

The Lockheed Super Constellation (L1049G pictured above), like earlier Constellation versions, had propellers in excess of 15 feet in diameter.  Extraordinarily tall landing gear was needed for the propellers to clear the ground.  The airframe was tapered downward toward the cockpit to mitigate front gear length.  The unique triple tail design provided the necessary control surface but allowed the plane to use hangers of the era which could not accommodate the height required for a single tail fin.    Photo courtesy of Ron Dupas, 1000aircraftphotos.com.

By 1944, the plane was ready for a demonstration flight that would shock the aviation industry.  With Howard Hughes as pilot and Jack Frye, TWA's president, as copilot, the Constellation flew across the country non-stop in a record-smashing six hours and fifty-seven minutes. Even fighter planes could not match the top speed of 340 miles per hour.

Unfortunately for TWA, the country's needs during WWII superceded those of commercial aviation, and the first production versions saw the Connie drafted as the C-69 military transport.  TWA had to wait until November 1945 to put the plane into the post-war skies and remake commercial aviation.  It was the first airliner able to fly nonstop coast to coast.  With a pressurized cabin it was able to fly at 20,000 feet, above most turbulence.  The Connie could carry an incredible 54 passengers over a distance of 3,000 miles at a cruising speed of 280 miles per hour.

By contrast, with the introduction of the DC-3 (DC standing for "Douglas Commercial") in 1936 Douglas continued its dominance of commercial aviation.  By 1939 90% of all air passengers were flying in the DC-3 or its predecessor, the DC-2.  The DC-3 had a range of 1,500 miles, a seating capacity of up to 28 passengers, a cruising speed of 192 miles per hour, and could reach 20,000 feet.  It had set a previous cross country record of 13 hours, 4 minutes, also with Jack Frye at the controls.

In October, 1950, an elongated version of the Constellation was introduced as the Super Constellation.  TWA first flew an improved Super Constellation in 1953.  In its various configurations, the Super Constellation could carry up to 109 passengers.  Prior to June 30, 1956, there had never been a passenger fatality on a Super Constellation during a scheduled domestic flight.

The Douglas DC-7 challenged the dominance of the Super Constellation with a slightly faster cruising speed and greater range.  Photo courtesy of Ron Dupas, 1000aircraftphotos.com.

United's DC-7.  The Douglas answer to the Super Constellation was DC-7, Douglas' largest and last piston aircraft.  It flew for the first time on May 18 1953, and began service with American Air Lines in November of that year.  The DC-7 had a flight crew of three, and in the standard configuration could seat 99 passengers at a speed of 330 to 400 mph, slightly faster than the Super Constellation.  With a range of 5,635 miles, it became the first commercial aircraft able to fly nonstop westbound across the United States against the prevailing winds.  United purchased 57 of the 105 DC-7's which Douglas produced.  Douglas eventually sold a total of 338 of the various DC-7 versions.  Prior to June 30, 1956, no DC-7 had been in a crash.

Take off.  At 9:01 AM, Pacific Standard Time, on Saturday, June 30, 1956, Trans World Airline's Flight 2 took off from runway 24 of Los Angeles International Airport.  The Lockheed 1049A Super Constellation was carrying 64 passengers and a crew of 6 on a flight to Kansas City, Missouri.  Its departure had been delayed from the scheduled 8:30 AM time by minor mechanical repairs.  Captain Jack S. Gandy was at the controls of the Super Constellation.  He had nearly 15,000 flying hours and would be proceeding along this route for his 178th time.

Three minutes later, United Air Line's Flight 718 lifted off runway 25L of Los Angeles International Airport.  Slightly behind it's schedule departure time of 8:45 AM, the Douglas DC-7 carried a crew of 5 and 53 passengers toward its destination of Chicago, Illinois.  Captain Robert F. Shirley headed up the United flight crew.  He had 17,000 hours of flight time and had flown the route since the preceding October.

TWA Flight 2, a Lockheed Super Constellation 1049A, and United Air Lines Flight 718, a Douglas DC-7, collided at 21,000 feet above the eastern edge of the Grand Canyon.  All 70 person on the TWA flight and 58 on the United flight were killed.

Flight plans.  TWA 2's flight plan called for an altitude of 19,000 feet and a 270 knot (310 mph) airspeed.  It was to fly under instrument flight rules (IFR), used when weather conditions do not meet minimum requirements for visual flight rules (VFR).  From LA, TWA 2's flight plan called for it to fly northeast to Daggett, CA, and from there to Trinidad, CO on a route with the ultimate destination of Kansas City, MO.  Although not specifically on its flight plan, TWA 2 would cross the Painted Desert between Daggett and Trinidad.

Painted Desert was not a specific point, but a line of position.  The plane's radio receiver could detect at which angle between 0 (magnet north) and 359 degrees the plane was at as it passed VOR (VHF Omni-directional Range) radio transmitters.  A plane would be at the Painted Desert line of position when it was at 321 degrees (the  321st radial) from the Winslow omni radio station.  This would correspond roughly with being over the Painted Desert which is just beyond the eastern edge of the Grand Canyon National Park.

United 718's flight plan called for an altitude of 21,000 feet and a 288 knot (330 mph) airspeed.  On leaving LA, United 718 would fly east northeast to Needles, CA, then to Painted Desert, AZ and Durango, CO on its route to Chicago, IL.

TWA 2 initially headed in a more northerly route than United 718, but their paths would of necessity cross as TWA 2 headed to Kansas City, which is about 200 miles south of United 718's Chicago destination.  This intersection would be immediately before the Painted Desert line of position near the eastern edge of the Grand Canyon.

In 1956, the Civil Aeronautics Administration tracked aircraft locations and directed flight paths by radio contact with pilots only in limited high traffic areas.  This controlled air space included the Los Angeles area, but both planes soon entered uncontrolled air space on their routes east.  The CAA would, however, continue to assign altitudes to planes even outside of controlled air space.

When flying on IFR in uncontrolled air space, planes would still maintain contact with air traffic control.  Since the pilot might have severely limited visibility, separation from other planes might depend solely on the altitude assigned.  Under VFR it was assumed that a pilot could see other aircraft and separation would be maintained on a "see and be seen" basis.

The cockpit of the TWA Constellation would have been much like that of the military L-749A version pictured above.  The "Bataan," on display at the Planes of Fame air museum at the Valle Airport (on Highway 64 between Williams to the Grand Canyon), was placed in service in 1949.  In its military career, it flew regular missions to Europe on the North Atlantic route during the Berlin airlift.  It was converted to VIP configuration in 1950 and served as General Douglas MacArthur's personal plane when he was the Supreme Commander of Allied Powers.  It flew the general to Wake Island in 1950 where President Truman awarded him the Distinguished Service Medal.  A year later it flew the general back to the states when he was fired by Truman.  After the famous plane was retired in 1966, it spent a brief time in surplus storage at Davis-Monthan AFB in Tucson.  NASA called the Bataan back from retirement within 6 months to participate in the Apollo space program.  It was retired for good in 1969.  [The clouds seen through the cockpit windows are superimposed, replacing the overexposed view of the parking lot.]  5-05

Change in altitude.  June 30 was not a sunny day.  The skies over northern Arizona and extending westward into Nevada were overcast.  Scattered thunderstorms had been predicted by the U.S. Weather Bureau and both companies' weather departments.  Probably because of weather conditions, as TWA 2 approached Daggett, Captain Gandy requested an increase in altitude from 19,000 feet to 21,000 feet through the TWA ground operator.  TWA's operator contacted the Los Angeles Air Traffic Control Center which, like the other control centers were part of the CAA.

The Los Angeles controller contacted the Salt Lake City control center saying, "TWA 2 is requesting two one thousand, how does it look?"  He noted the TWA 2 route from Daggett to the next checkpoint.  "I see," he continued, "you have United 718 crossing his altitude--in his way at two one thousand."

The Salt Lake controller responded, "Yes, their courses cross and they are right together."

The LA controller then called the TWA ground radio operator with the message, "Advisory, TWA 2, unable to approve two one thousand."

The TWA ground operator interrupted.  "Just a minute.  I think he wants a thousand on top, yes a thousand on top until he can get it."  A clearance of "1,000 feet on top" would allow TWA to adjust its altitude to whatever elevation 1,000 feet above the adverse weather conditions might be.  Being on top of the weather would mean that visibility should be adequate for VFR "see and be seen" rules.

The LA controller determined that TWA 2 was already "1,000 on top" at its present 19,000 foot altitude.  He issued the clearance with a caution, "ATC clears TWA 2, maintain at least 1,000 on top.  Advise TWA 2 his traffic is United 718, direct Durango, estimating Needles at 9:57."

The director of the CAA Office of Air Traffic Control later explained to accident investigators that air traffic control had responsibility for separation only for IFR (instrument) flights.  As a result, TWA 2 was denied 21,000 feet.  When TWA 2 made the amended request, it was requesting a VFR (visual) clearance under which air traffic control had no responsibility for separation since it was presumed that planes would be able to see each other.

At 9:58 United 718 reported its position to the CAA communications station in Needles.  It was then over Needles flying at 21,000 feet, and estimated reaching the Painted Desert line of position just beyond the eastern end of the Grand Canyon at 10:31.  All times continue to be reported as Pacific Standard Time although the flights would pass into the Mountain Time Zone at the Arizona border.

At 9:59 TWA 2 reported its position to the company radio station in Las Vegas.  It had passed Lake Mohave (on the Arizona border) at 9:55, was 1,000 on top at 21,000 feet, and would be reaching the Painted Desert checkpoint at 10:31.

Temple Butte and Chuar Butte, the final resting places for the TWA Constellation and the United DC-7, can be seen in the far distance from the Watchtower at Desert View, the easternmost viewpoint on the South Rim.  11-02.

At 10:13, the Salt Lake controller had the last position reports made by each of the flights.  He knew that both planes were at 21,000 feet.  He knew that they were on converging courses.  He knew that they both estimated arriving at the Painted Desert at exactly the same time.  He did not advise either flight of any of this information.  That was not his responsibility according to Civil Aeronautics Board's Accident Investigation Report.  The planes were flying under visual flight rules, in uncontrolled air space.

It was not unusual for captains to deviate slightly from the most direct route as they approached the Grand Canyon in order to give their passengers a spectacular view of the canyon from above.  On June 30, 1956, it seems unlikely that any sightseeing occurred.  Considerable high and low clouds with some showers covered the Grand Canyon, particularly to the east.  The top of most of the cloud cover was later estimated to be at 15,000 feet, with some of the larger formations rising to 25,000 feet.  From their 21,000 foot altitude, their view of the canyon would be obscured unless they happened on a brief break in the cloud cover.

The estimated arrival times of both flights at the Painted Desert line of position shared the same error.  It would have taken both flights 3� minutes more than their estimates to reach that point.  Investigators could not explain this delay.

Weather information, which investigators did not conclude explained the delay, indicates that the winds aloft had become more westerly as the flights approached the canyon, and by 11:00 AM scattered thunderstorms were expected to develop along a line from Denver to Phoenix which would include the eastern edge of the canyon.  Moderate to severe turbulence was forecast in the thunderstorms, with buildups expected to develop to 30,000 feet, protruding through the lower cloud cover.

At around 10:31 the planes were still over the Grand Canyon just minutes away from the Painted Desert.  They had, however, tragically reached the that point at which their paths would cross.  At this crucial point, for whatever reason, they did not or could not see each other.

"We're going in."  At 10:31 AM Pacific Standard Time, communicators in Salt Lake City heard the ominous radio message, "Salt Lake, United 718 ... ah ... we're going in."  Though not audible to Salt Lake City communicators, laboratory analysis of the transmission recording detected a speaker in the background excitedly calling what could possibly be "pull up" during the "ah" and pause in the transmission.

The DC-7 was behind and to the right of the Constellation as it overtook the slightly slower craft.  The DC-7 approached, moving forward and to the left relative to the Constellation.  The initial impact occurred when the tip of its left wing aileron struck the front of the Constellation's center tail fin.  In the course of less than half a second, the lower surface of the DC-7's wing smashed into the upper fuselage of the Constellation with destructive force.  The DC-7 continued moving left dragging its far left engine across Constellation's roof as its propeller chewed deeply into the rear cabin.

The collision ripped open the fuselage of the Constellation from just forward of its tail to near the main cabin door.  The tail section of the Constellation separated almost immediately and plummeted toward the canyon below.  With its tail severed, the Constellation pitched down and fell in a steep trajectory to the canyon floor.

Temple Butte rises from the west side of the Colorado River, about a mile downstream from its juncture with the Little Colorado.  It is about sixteen miles northeast of the national park's center at Grand Canyon Village.

The main section of the Constellation made a fiery, destructive impact with the northeast slope of Temple Butte at an elevation of 3,400 feet.  The wreckage came to rest along a southwesterly heading with sections of the fuselage scattered along the slope on the north bank of the Colorado and nose portions lying across the river on its south bank. An intense ground fire followed the impact.

The tail section of the Constellation landed, nearly intact, 550 yards north of the main wreckage.

While the damage to the DC-7 was not as severe, it was nevertheless terminal.  Most of its left outer wing had been torn off during the collision.  Although much of the wing remained, damage restricted aileron control.  It fell less steeply probably on a turning path toward the canyon below.

Immediately west of the confluence of the Colorado and Little Colorado Rivers, Chuar Butte rises to 4,050 feet from the floor of the Grand Canyon.  As the DC-7 descended to 4,040 feet, it struck the shear south face of Chuar Butte with devastating force.  The plane disintegrated on impact.  Major components fell into an inaccessible chimney and upon sheer ledges, and burst into flame.  Some pieces of the DC-7 wing were later found mixed with the Constellation wreckage.

Neither flight reported passing the Painted Desert line of position, which both planes estimated they would reach at 10:31.  CAA and company ground communications made repeated attempts to contact the flights.  A radio search was made by several stations along their proposed routes.  At 11:51 a missing aircraft alert was issued, and search and rescue procedures were implemented.

Scenic Grand Canyon flight pilot discovered wreckage.  That evening brothers Palen and Henry Hudgin who operated the Grand Canyon Airlines which provides scenic flights heard about the missing aircraft.  One of the brothers recalled seeing light smoke rising from the canyon earlier in the day.  They flew back to the area and during a low pass were able to identify the tail section of the TWA Super Constellation.  They found the major portion of the Constellation, but were unable to see any evidence of survivors.  

The next day they returned to the area where the Super Constellation lay.  They discovered wreckage of the United DC-7 1.2 miles northeast of the Constellation.  Again, there was no evidence of survivors.

Removal of bodies begins.  Army helicopters made several brief visits to the TWA crash site on July 1, but no personnel were left on the site.  Then, at 6:15 AM Mountain Standard Time, on Monday, July 2, two army H-21 Piasecki twin-rotor helicopters took off to begin the task of recovering the crash victims.  They ferried a dozen Federal investigators, public officials, and airline executives along with Army medical personnel to the site.  Federal officials included representatives of the Civil Aeronautics Board, the agency that administers commercial aviation, and of the Civil Aeronautics Authority which regulates flying operations following the rules that the CAB writes.

The first Monday morning helicopter flight also carried the acting Coconino County Coroner who had the important task of declaring the victims dead so that their bodies, or more accurately, the remaining parts of their bodies could be taken to the mortuary.  As the investigation began, the helicopters took rubberized shrouds containing body parts from the crash site to the Grand Canyon Airport for transport to an improvised mortuary at an armory in Flagstaff.

A helicopter first landed on the tiny pinnacle of Chuar Butte, ten feet above the point at which United 718 crashed, on July 5.  The pinnacle was barely larger than the footprint of the helicopters that were landing there.  One of the pilots noted that if he missed his mark by only a few feet he would end up in the canyon below with the DC-7 wreckage.

67 of the TWA passengers and crew are interred in a common plot in the Citizen's Cemetery in Flagstaff.  5-05.

The unidentified remains of 29 of the United victims are interred at the Grand Canyon Cemetery in the Grand Canyon National Park.  5-05.

The helicopter brought two mountaineers to the pinnacle where they would descend the sheer side of the butte where they would start the search for bodies. As they located bodies, clues emerged.  A piece of cowling from the DC-7 was brought out with a scrap of metal painted red and white like the color of TWA Super Constellation.

Eight Swiss mountaineers also came to help in the recovery operation as a result of an offer from the Chairman of the Board of Swiss Air made to the President of United Air Lines.  The team was made up of members of the  Swiss Air Rescue Patrol, a 90-member volunteer group founded in 1951 with members from various professions.  The eight volunteering for the Grand Canyon recovery ranged in age from 27 to 44, and were headed by a 35 year old air traffic control operator from the Zurich airport.  Swiss Air provided free transportation to New York, and United picked up their expenses in this country.

Mass burial.  On July 9, funeral services were held for 67 of the TWA victims at the Citizen's Cemetery in Flagstaff.  Roman Catholic, Protestant, Jewish and Mormon clergymen conducted services before the coffins were buried together in the 24 by 72 foot Grand Canyon Memorial Plot.  About 350 relatives and friends attended the services with 1,500 other mourners including Arizona's Governor Ernest McFarland and TWA's executive vice president.

The bodies of exactly half of the United passengers were identified and returned to their homes for burial.  The 29 unidentified victims were represented by four coffins interred below a United Airlines Accident Memorial in the Grand Canyon Cemetery on the south rim of the canyon, just steps away from the Shrine of the Ages.  Another monument was erected for the TWA crash victims at Citizens Cemetery in Flagstaff, Arizona.

The Civil Aeronautics Board issued its Accident Investigation Report on April 17, 1957.  Click on the picture to view the full 24 page report in pdf format.

Who was at fault?  As the investigation proceeded, the finger-pointing began.  Just 7 days after the crash, the CAB's chief investigator told a House subcommittee that TWA 2 bore the primary responsibility for the collision.  Since TWA 2 was on VFR see and be seen rules, he explained, it could vary its altitude as it found appropriate.  United 718 was on IFR and was required to maintain the altitude assigned to it.  TWA 2 had also been advised of the United 718 traffic, but the reverse was not true.

Almost immediately after the chief investigator had disclosed his conclusion, the Director of the CAB's Bureau of Safety Regulations recanted any assessment of blame on TWA.  "Outside of controlled areas," he said, "there are no instructions that are pertinent or binding.  Both pilots were on their own."

Before the bodies had even been retrieved from the canyon, Congress got involved.  The House Commerce Committee appointed a special subcommittee that would fly to the scene and look into the tragedy.  Members of the Senate Commerce subcommittee on aviation expected the accident to end a five year deadlock on air navigation problems.

The president of the 11,000 member Airline Pilots Association placed the blame squarely on the CAB regulations.  He pointed to a series of airliner accidents resulting from the faulty airline traffic regulation procedures.  He contended that the existence of a dual system of rules (VFR and IFR) was not adequate for the growing volume of air traffic.  He pointed to the limited visibility from the cockpit which compounded the problem.  While pilots can see horizontally over a sweep of about 180 degrees with partial upward visibility, they cannot see behind them or downward.  He said that it would have been possible for the two planes to have been flying closely for many minutes in position in which neither was aware of the other.  His solution would be the complete regulation of all flights, but, he noted, the CAA's budget had been steadily reduced in recent years.

The statistics supported the Airline Pilots Association position.  In 1956, U.S. airlines were involved in four near-crashes each day, mostly in clear weather.  Since 1950 there had been more than 65 mid-air collisions by civilian aircraft.  The early consensus pointed toward the traffic control system as the cause of the tragedy.

The CAA did not see it that way.  It was true, the administration said, that the system had to be improved and enlarged for the forthcoming jet planes.  However, it claimed to provide the world's "finest air-traffic control system." 

The Airline Pilots Association position was also denounced by the Airline Owners and Pilots Association, saying that the TWA and United pilots had "deliberately chosen not to use" a perfectly adequate system available to them.

When the CAB's Accident Investigation Report was released on April 17, 1957, it came to the remarkably unexplanatory conclusion: "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."  The Board only speculated as to reasons that the pilots did not see each other.  Pointing to no one possibility as more likely than another the report list (1) clouds, (2) aircraft window design, (3) preoccupation with cockpit duties or providing passengers with a view of the canyon, (4) physiologic limitations of human vision, and (5) insufficient air traffic advisory information.

A series of unfortunate events.  Like most catastrophic events, the United 718/TWA 2 collision would not have occurred if any one of a series of unfortunate choices or events had not occurred.  (1) If the planes had swapped their first destination and TWA 2 flown via Needles and United 718 via Daggett, their paths would have never crossed.  (2) If TWA 2 had not been delayed 31 minutes, it would have safely passed the point of intersection long before United 718 reached that point.  (3) If TWA 2 had stayed at 19,000, they would crossed safely 2,000 feet below United 718.  (4) If the Salt Lake controller had advised the planes of the information he had at hand indicating a risk of an imminent collision, the pilots might have been able to take last minute steps to avoid the collision.

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