Lockheed 1049A accident at Grand Canyon, Arizona, 30 Jun 1956

Accident narrative

At approximately 1031 Pacific standard time on June 30, 1956, a Trans World Airlines Lockheed 1049A and a United Air Lines Douglas DC-7 collided at about 21,000 feet over the Grand Canyon in Arizona. Both aircraft fell into the canyon near the confluence of the Colorado and Little Colorado Rivers. There were no survivors among the 128 persons aboard the flights (70 aboard TWA and 58 aboard United), and both aircraft were destroyed.

### The Flights

Trans World Airlines Flight 2 was a regularly scheduled passenger service from Los Angeles, California, to Kansas City, Missouri. The flight plan proposed an instrument flight rules (IFR) routing via Green Airway 5, Amber Airway 2, Daggett direct Trinidad, direct Dodge City, and Victor Airway 10 to Kansas City, with a cruising altitude of 19,000 feet and a true airspeed of 270 knots.

The flight departed Los Angeles at 0904. The crew consisted of Captain Jack S. Gandy, Copilot James H. Ritner, Flight Engineer Forrest D. Breyfogle, Flight Engineer Harry H. Allen (aboard as an additional crew member), and Hostesses Tracine E. Armbruster and Beth E. Davis. Captain Gandy had nearly 15,000 flying hours and had flown the subject route approximately 177 times. The aircraft departed with 3,300 gallons of fuel at a gross weight of 108,115 pounds, well under its maximum allowable weight.

United Air Lines Flight 718 was regularly scheduled from Los Angeles to Chicago, Illinois. It took off at 0904, three minutes after TWA 2. The IFR flight plan proposed a routing via Green Airway 5 Palm Springs intersection, direct Needles, direct Painted Desert, direct Durango, direct Pueblo, direct St. Joseph, Victor Airway 116 Joliet, and Victor Airway 84 to Chicago. The plan proposed a cruising altitude of 21,000 feet and a true airspeed of 288 knots.

The United crew consisted of Captain Robert F. Shirley, First Officer Robert W. Harms, Flight Engineer Gerard Fiore, and Stewardesses Nancy L. Kemnitz and Margaret A. Shoudt. Captain Shirley had accumulated 16,492 flying hours and had flown the operation since October 1955. The DC-7 departed with 3,850 gallons of fuel at a gross weight of 105,835 pounds, less than its restricted maximum allowable weight.

### En Route Communications

After takeoff, both flights were vectored through a local overcast in the Los Angeles area and reported "on top." Los Angeles Air Route Traffic Control Center (ARTC) cleared both flights according to their filed flight plans, specifying that their climbs to assigned altitudes be in visual flight rules (VFR) conditions.

At 0921, approaching Daggett, TWA 2 requested a change in its flight plan altitude assignment from 19,000 to 21,000 feet. The Los Angeles controller contacted the Salt Lake ARTC controller, noting that TWA 2 was requesting 21,000 feet and that United 718 was crossing his altitude. The Salt Lake controller replied, "Yes, their courses cross and they are right together."

Los Angeles ARTC then advised TWA 2 that they were unable to approve 21,000 feet. The TWA radio operator interrupted to request a clearance of 1,000 feet on top. After ascertaining that the flight was at least 1,000 on top, ARTC cleared TWA 2 to maintain at least 1,000 on top, and advised the flight that its traffic was United 718, direct Durango, estimating Needles at 0957. The TWA ground radio operator stated that Captain Gandy acknowledged the information on the United flight as "traffic received."

At 0958, United 718 reported to the CAA communications station at Needles that it was over Needles at 21,000 feet, estimating the Painted Desert at 1031.

At 0959, TWA 2 reported to company radio at Las Vegas that it had passed Lake Mohave at 0955, was 1,000 on top at 21,000 feet, and estimated it would reach the Painted Desert line of position at 1031. This was the last routine radio communication with the flight.

At 1031, Aeronautical Radio communicators at Salt Lake City and San Francisco heard an unidentified transmission. By playing back the recorded transmission, it was later determined to be from United 718. The context was interpreted as: "Salt Lake, United 718... ah... we're going in." Laboratory analysis of the recording revealed a second speaker in the background yelling "up... up," along with other indefinite words fitting energy patterns of "look," "pull," or "come." The analysis showed both speakers were speaking at a pitch well above normal, indicating they were under great emotional stress and already in serious trouble.

### Search and Wreckage Recovery

When neither flight reported passing the Painted Desert, a radio search was initiated, followed by a missing aircraft alert at 1151. That evening, a scenic flight pilot who had seen light smoke rising from the canyon earlier in the day returned to the area and identified the empennage of the TWA Constellation. The next day, a second wreckage was located approximately one mile from the first.

The L-1049 Constellation crashed in a draw on the northeast slope of Temple Butte at an elevation of 3,400 feet. The wreckage was strewn along a southwesterly heading, indicating the aircraft contacted the ground at a steep angle and was inverted at initial impact. Severe disintegration and an intense ground fire caused nearly total destruction.

The main wreckage area of the DC-7 was located 1.2 statute miles northeast of the L-1049 area. The DC-7 struck the south face of Chuar Butte about 10 feet below the top of the ridge at an elevation of 4,050 feet. Initial impact was on a northeast heading with the aircraft nosed down and its right wing below a level attitude. Major components fell into an inaccessible deep chimney and upon sheer ledges below.

### What the Investigation Found

During the structural investigation, several areas of damage conclusively established that an inflight collision had occurred.

The left outer wing panel of the DC-7, representing a length of about 20 feet from the tip inboard to station 453, separated in flight. The largest single piece was found about one-third mile west of the TWA wreckage site. The wing tip cap was deformed upward and inboard, bearing black rubber smears from the L-1049 deicer boot and red paint smudges from the L-1049. Scratches on the lower wing surface ran diagonally aft and inboard at approximately 25 degrees relative to the wing center spar line. Two pieces of the DC-7 left aileron were severely buckled inboard and upward, bearing heavy black rubber smears.

At the L-1049 wreckage area, a section of lower wing skin from the DC-7 was found bearing scrape marks corresponding directionally to those on the outer panel. Imbedded in a tear on this part was a piece of Constellation headlining used in the aft cabin ceiling.

The Constellation empennage was found generally intact, except for the left and right fins and rudders, about 550 yards north of the main TWA wreckage, showing it had separated in flight. Sections of the left upper fin leading edge bore collision evidence: one piece was concaved by an object moving right to left, fitting precisely with the damage on the DC-7 left wing tip.

In the L-1049 aft fuselage, a piece of skin from the upper right side was bent inward about 90 degrees. Its white outer surface bore red, blue, and black marks, along with gray deposits creating a stippled effect, indicating an object moving up and along the circumferential frames. Additionally, a series of three propeller cuts were found in the lower fuselage in the vicinity of the rear baggage compartment. The cuts were generally upward and inboard, about 35 inches apart, with red and blue paint marks coinciding with the paint scheme on the DC-7 propeller.

### The Collision Sequence

From the physical damage, the Board determined that the initial impact occurred with the DC-7 moving from right to left relative to the L-1049, and with the L-1049 moving to the right and aft relative to the DC-7. The angle between the aircraft at the instant of impact was approximately 25 degrees relative to their longitudinal axes. The DC-7 was rolled approximately 20 degrees right wing down relative to the L-1049.

First contact involved the center fin leading edge of the L-1049 and the left aileron tip of the DC-7. Instantly thereafter, the lower surface of the DC-7 left wing struck the upper aft fuselage of the Constellation with disintegrating force, destroying the aft fuselage and the structural integrity of the left wing outer panel. As the aircraft passed laterally, the left fin leading edge of the Constellation and the left wing tip of the DC-7 made contact. During this same time, the DC-7 No. 1 propeller inflicted a series of cuts in the L-1049 aft baggage compartment.

The Board concluded this entire sequence occurred in less than one-half second. The collision ripped open the Constellation's fuselage and caused its empennage to separate almost immediately. The L-1049 then pitched down and fell on a short forward trajectory. The DC-7, having lost most of its left outer wing, fell less steeply, probably on a turning path.

The Board found no evidence of malfunction in either aircraft prior to impact.

### Air Traffic Control and Separation

Both flights were planned as high-altitude operations off airways over direct courses. United's policy permitted high-altitude flights on IFR or VFR flight plans but prohibited flying in instrument weather conditions off airways. TWA's policy permitted off-airways flights in instrument weather only on an IFR flight plan with an assigned altitude; when operating 1,000 on top, the company required adherence to visual flight rules.

At approximately 1013, the Salt Lake controller received the position reports from both flights. He was aware that both aircraft were operating at 21,000 feet, were on converging courses, and were estimating the Painted Desert at the same time. He advised neither flight of this situation.

The Board noted that Air Traffic Control undertakes to separate IFR traffic only within controlled airspace. Outside controlled airspace, ATC exercises no control, and its principal function is to monitor flight progress to provide an orderly flow into the next control area. The CAA Director of Air Traffic Control testified that advisory service for traffic in uncontrolled areas would be tantamount to positive control, requiring personnel and facilities not presently available. The Board concluded that existing ATC policies and procedures did not require the controller to offer traffic advisory information voluntarily.

Because the flights were in uncontrolled airspace, separation depended on the "see and be seen" principle, which expressly places the responsibility on pilots to visually provide separation between aircraft in VFR weather conditions, regardless of flight plan or clearance.

### Weather and Flight Progress

Forecasts predicted high broken clouds with light rain showers in the Colorado River area, and scattered thunderstorms expected to develop to 30,000 feet or higher. Pilots flying near the accident area reported an overcast top at approximately 15,000 feet with few breaks. They also noted towering cumulus clouds, including one over the immediate Grand Canyon Village area and others farther east and northeast, extending to 25,000 feet or higher.

The Board believed that weather conditions at 21,000 feet would not have precluded flight in VFR conditions, but that deviations may have been required to circumvent the buildups. Based on weather conditions, company procedures, and good pilot practice, the Board formed the firm opinion that both flights were operating according to rules prescribed for VFR conditions when the collision occurred.

Both flights were approximately 17 miles, or nearly 3-1/2 minutes' flying time, west of their estimated positions when the collision occurred at 1031. The Board reached no definite conclusion as to the cause of this delay, noting possibilities including maneuvering to provide a more sceni