Docket No

Docket No. SA-113 File No. 257-46

CIVIL AERONAUTICS BOARD

ACCIDENT INVESTIGATION REPORT

Adopted December 24, 1946 Released: January 6, 1947

UNITED AIR LINES, ELK MOUNTAIN, WYOMING - January 31, 1946

The Accident

United Air Lines' Flight 14 en route from Boise, Idaho, to Denver, Colorado, crashed near the top of Elk Mountain, Wyoming, at 0247 * January 31, 1946. All 21 occupants of the aircraft were fatally injured and the Douglas DC-3 was demolished by impact and fire.

History of the Flight

Flight 14 departed Portland, Oregon, at 2020 January, 30, 1946, with stops scheduled at Penaleton, Oregon, and Boise, Idaho. After being serviced at Boise, the aircraft departed at 0007 January 31, 1946 to cruise nonstop to Denver, Colorado. The original flight plan authorized prior to departure from Boise specified a cruising altitude of 9,000 feet between Boise and Malad City, Idaho, 11,000 feet between Malad City and Rock Spring, and 13,000 feet between Rock Springs and Denver. Until the aircraft arrived over Rock Springs, the flight was conducted without any apparent difficulty. However, as the flight approached Rock Springs the captain requested and received a change of flight plan in order to remain at 11,000 feet.

Approximately at the time Flight 14 reported over Rock Springs, United Air Lines' Flight 44, en route from Oakland, California, to Cheyenne, Wyoming, transmitted a position report over that station at the same altitude. As the two aircraft approached Sinclair at 11,000 feet, the pilots of Flight 44 observed the lights of Flight 14 approximately one mile ahead and apparently on the left side of the airway. The two aircraft appeared to be on converging flight paths and, before reaching Sinclair, Flight 14 was directly ahead of Flight 44. The crew of the latter aircraft observed that Flight 14 appeared to pass over the range station at Sinclair, Wyoming, and to take up a heading directly toward Laramie, Wyoming. Flight 44, meanwhile, maintained a course close to the left hand side of the airway and the pilots continued to watch Flight 14 as it bore to the right in the direction of Elk Mountain. Having encountered scattered-to-broken clouds at his cruising altitude in an area approximately 30 miles east of Sinclair, the captain of Flight 44 climbed to 11,300 feet where he was able to cruise above all clouds. From this point, the lights of Flight 14 were intermittently visible to the co-pilot of Flight 44 through breaks in the clouds and the aircraft appeared to be approximately three miles to the right of the airway slightly below the cruising altitude of Flight 44.

Shortly thereafter the co-pilot of Flight 44 observed a bright flash off to his right and a red fire which appeared to glow through the clouds. Fearing that an accident had occurred to Flight 14, the pilot of Flight 44 immediately attempted to establish contact with it without success. At approximately the time of the accident United Air Lines' Flight 28 was proceeding westward from Laramie at an altitude of 12,000 feet and also observed the bright red glow from the vicinity of Elk Mountain. Subsequent attempts to contact Flight 14 by ground stations were unsuccessful and it became apparent that the flight had struck Elk Mountain.

Investigation

An aftercast of the weather situation at the time and in the vicinity of the accident indicated that winds aloft were from 300 degrees to 310 degrees, between 50 and 55 miles per hour. A United Air Lines' pilot operating over this portion of the airway testified that scattered-to-broken clouds existed at 11,000 feet. This observer also indicated that there was a definite overcast around the summit of Elk Mountain extending approximately five miles in all directions. Although the clouds were reported to have been 300 feet in thickness it was estimated that in the immediate vicinity of Elk Mountain clouds could have been between 500 and 1,000 feet in thickness.

Adverse weather conditions prevailing seen after the accident delayed the arrival at the scene of investigators of the Safety Bureau of the Civil Aeronautics Board. Although several attempts were made to climb Elk Mountain the following day by personnel from local army stations, extremely low temperature and heavy snowdrifts made it impossible. Approximately seven days after the accident had occurred, a Board investigator was able to reach the scene of the accident and to accomplish a cursory inspection of the wreckage. Because of the impossibility of completing a satisfactory examination due to the heavy snow which covered the wreckage, arrangements were made to return to Elk Mountain during late June at which time most of the snow would have melted from the scene of the accident.

On June 25, investigation of the wreckage was continued under more favorable conditions. With the exception of the left engine which had rolled over the crest of the hill and into a large snowbank, most of the debris was accessible for inspection. Examination of the seats and the broken seat belts indicated that both pilot and co-pilot were at their respective stations at the time of impact. Marks of impact on the ground indicated that the aircraft was in approximately level flight at the time of the accident. Distinct propeller marks had been cut in the face of the mountain and both wings were torn completely from the fuselage. The fuselage disintegrated as it slid up the mountain slope for a distance of approximately 200 yards. Some parts of the aircraft continued along the direction of flight over the top of the ridge rolling down the east side.

Inspection of the radio panel disclosed the fact that the ADF receiver was tuned to 235 kilocycles at the time of the accident and that the range receiver was tuned to 212 kilocycles. The frequency of the Laramie radio station is 236 kilocycles and that of Sinclair is 212.

A survey of the direction of flight at the time of impact indicates that Flight 14 was on a magnetic course of 80 degrees at the time of the accident. Inasmuch as winds of 51 to 55 mph at a relative wind angle of 235 degrees were experienced, it is probable that approximately 14 degrees of wood drift would have been experienced along the course between Sinclair and Laramie. Laramie is on a magnetic bearing of 98 degrees from Sinclair and, if the wind conditions remained constant throughout the course, a magnetic heading of 84 degrees would have been required to negotiate such a course.

The airway eastward, from Sinclair parallels the center of the east ***, of the Sinclair range to the intersection with the northwest leg of the Laramie range. From this point it bends sharply to the right toward Laramie on a heading of 137 degrees. The distance between Sinclair and Laramie via Airway Green 3 is 88 miles while the distance between the two range stations on a direct course is 79 rules. The point of impact on the southwest corner of Elk Mountain at an elevation of approximately 10,822 feet is located on a direct line between the Sinclair and Laramie radio range stations. The flight path of the aircraft in the vicinity of the accident had deviated south of the airway a distance of approximately 4-1/2 miles. Elk Mountain represents the highest terrain between Sinclair and Laramie within an area of 15 miles on either side of the direct course. The dog-legged airway was so designed in order to provide most effective clearance from the high terrain to the south.

The captain and recently returned to duty with United Air Lines after a tour of duty of two and one-half years with the army Air Forces. Upon his return to United he was given six one-way qualifying trips over the route, two as a co-pilot and four as an observer riding the "jump" seat. The first officer was making his first scheduled flight over this route.

Investigation of Civil Aeronautics Administration communications records for the period including the time at which the accident occurred indicates that all navigation aids including beacon lights and radio facilities were functioning normally at the time of the accident.

That region of Wyoming in the vicinity of Elk Mountain is very sparsely settled and no witnesses were located who had either seen or heard Flight 14 from the ground immediately prior to or at the time of impact.

Discussion

The elevation at the top of Elk Mountain is 11,162 feet. Flight 14 struck Elk Mountain at an elevation approximately 340 feet below that of the crest of the mountain and approximately 180 feet below the assigned cruising altitude. Such a deviation cannot be considered unusual and could be explained be decrease in the barometric pressure as the flight proceeded eastward and the unusually low temperature encountered in that area.

The magnetic heading required under the conditions of the winds aloft and magnetic variation in the area of Elk Mountain in order to maintain a direct course between Sinclair and Laramie was approximately 84 degrees. Although it has been determined that the aircraft was actually on a magnetic course of 80 degrees at impact, the point of impact was on a direct line from the Sinclair to the Laramie radio range stations the magnetic bearing of which is 98 degrees. It is unlikely that the same wind direction and velocity would have prevailed at the surface of Elk Mountain and the actual wind draft experienced by Flight 14 immediately prior to impact is impossible to determine. It therefore appears that Flight 14 had deviated from the airway in order to maintain a direct course between these two points. This conclusion is further confirmed by the fact that the aircraft ADF receiver was tuned to the frequency of the Laramie radio range station. Although the possibility may exist that the deviation from the airway had been a result of wind drift, it is apparent that the captain of the flight was aware of the winds aloft inasmuch as he had navigated without apparent difficulty to Sinclair from Portland, Oregon. It is extremely unlikely, therefore, that such wind drift was experience without the knowledge of the captain.

Testimony of pilots operating along Airway Green 3 at approximately the time of the accident and weather data furnished by the Weather Bureau indicate the likelihood that Flight 14 encountered come clouds in the area of Elk Mountain and that at the time of impact the pilot was actually "on instruments".

No evidence was disclosed as a result of examination of the wreckage, inspection of the aircraft maintenance records or testimony of the pilots of Flight 44 to indicate failure of either the powerplants or the aircraft structure. The request by the captain for charge in clearance to permit the flight to remain at 11,000 feet and the fact that the point of impact was a * an elevation reasonably close to 11,000 feet indicate that the pilot was experiencing no undue difficulty in maintaining his cruising altitude. Impact marks on the face of the mountain further indicate that the aircraft was in straight and level flight and apparently under control. It must be concluded, therefore, that the pilot maintained a cruising altitude which did not provide adequate clearance over Elk Mountain, that the pilot departed from the normal course along Airways Green 3; and that the aircraft struck Elk Mountain while "on instruments".

Findings

On the basis of all available evidence, the Board finds that:

The pilots, aircraft, and crew were properly certificated for the flight.

An instrument flight plan was authorized for Flight 14 which included a cruising altitude of 13,000 feet between Sinclair, Wyoming, and Laramie, Wyoming.

When over Rock Springs range station the captain requested and received approval of a change of flight plan in order to permit him to remain at 11,000 feet.

Until reporting over Sinclair, Wyoming, the flight had been entirely routine.

The flight deviated from the prescribed route and followed the most direct course between Sinclair and Laramie.

The ADF receiver was tuned to the Laramie radio range station.

At 0247, Flight 14 collided with Elk Mountain at an elevation approximately 180 feet below its assigned cruising altitude and 4 1/2 miles south of Airway Green 3, and was demolished by impact and fire.

Probable Cause

On the basis of the foregoing the Board finds that the probable cause of this accident was the deviation from the prescribed route at an altitude insufficient to assure adequate clearance over Elk Mountain.

BY TEE CIVIL AERONAUTICS BOARD:

/S/

OSWALD RYAN

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/S/

HARLLEE WATCH

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/S/

JOSH LEE

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Landis, Chairman, and Young, Member, did not take part in the decision.

SUPPLEMENTAL DATA

Investigation and Hearing

The Civil Aeronautics Board was notified of the accident at 0445, January 31, 1946, and an investigation was initiated in accordance with Section 702 (a) (2) of the Civil Aeronautics Act of 1938, as amended. Air Safety investigators of the Board's Kansas City office proceeded immediately to Denver, Colorado, to make arrangements for visiting the scene of the accident. Because of the nature of the terrain and the severity of the weather conditions, it was impossible for investigators to climb Elk Mountain immediately for an inspection of the wreckage. In view of the fact that Army personnel and a Board investigator reported that the wreckage was covered with snow and that parts of the aircraft were buried deeply in snowdrifts, it was decided that a detailed inspection would not be feasible until well into the summer. An inspection of the wreckage was a accomplished June 25, 1946. However, a public hearing was ordered by the Board and was held at Cheyenne, Wyoming, February 15 and 16, 1946.

Air Carrier

United Air Lines was incorporated under the laws of the State of Delaware and has established its headquarters at Chicago, Illinois. At the time of the accident the company was operating under a Certificate of Public Convenience and Necessity and an Air Carrier Operating Certificate, both issued pursuant to the Civil Aeronautics Act of 1936, as a mended. These certificates authorized United Air lines, Inc., to engage in air transportation of persons, property and mail between various points, including Boise, Idaho, and Denver, Colorado.

Flight Personnel

Captain Walter Paul Briggs, Portland, Oregon, age 43, had been employed by the company since September 1, 1931, and had accumulated a total of 13,003 hours, of which 2,909 hours had been obtained in DC-3 equipment. First Officer Harry N. Atlas, Helena, Montana, age 27, was co-pilot and had been employed by the company since October 5, 1945. He had accumulated a total of 2,021 hours, of which 21 hours had been obtained in the service of United Air Lines as co-pilot in DC-3 equipment. Dorothy J. Carter of Portland, Oregon, was Stewardess.

Aircraft

The Douglas DC-3, NC-25675, had been operated a total of 16,333 hours, of which 2,602 had been accumulated since the last major overhaul. Two Pratt and Whitney R1830-92 engines were installed and were equipped with Hamilton Standard, hydromatic propellers. The left and right engines had accumulated a total of 15,794 hours and 12,659 hours, respectively, each having been operated a total of 288 hours since over haul. At the time of take-off from Boise, the total weight of the aircraft was within its maximum gross limits and the load was distributed with respect to its center of gravity within approved limits.

Figure

Airway green 3 between Sinclair and Laramie, Wyo., Jan. 31, 1946.

CIVIL AERONAUTICS BOARD

WASHING, D.C.

Date

March 1, 1946

To:

Assistant Director - B-81

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From:

Chief, Investigation Division B-95

Reply for my signature.

For your information.

See me reference this.

Please handle.

Investigate and report.

Comments:

***

Allentown-***

Baltimore

Boston

Camden

Chicago

Cincinnati

Cleveland

Columbus

Dayton

Jacksonville

Memphis

Miami

New York

Pittsburgh

Portland

Richmond

Savannah

Tampa

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Washington

W. Palm Beach

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TOTAL

In accordance with the recent policy of the Safety Bureau the following is a summary of the facts, conditions and circumstances disclosed at the hearing of United Air Lines' accident to Flight 14 at Elk Mountain, Wyoming on January 31, 1946. This summary is quoted from memory since the transcript of the hearing is not available at this time.

FACTS, CONDITIONS AND CIRCUMSTANCES.

Accident involving United Air Lines' aircraft No. 89675 at Elk Mountain, Wyoming, approximately 0247, January 31, 1946. Flight 14 departed Portland, Oregon, at 2020 on January 30, 1946. the flight plan was submitted in accordance with the usual procedure and was approved by the dispatcher prior to the departure of the aircraft. Flight then proceeded to Boise with stop at Pendleton, Oregon, in a routine manner upon which we have no comments to make. After being serviced at Boise, the flight consisting of a crew of three and eighteen passengers departed non-stop to Denver which is normal proceedure when weather over the airway permits such an operation, otherwise flight stops at Rock Springs, Wyo., for refueling.

***

A complete examination of the wreckage was impossible due to the extreme adverse weather conditions prevailing at the scene of accident, which, however was reached by one of the Board's Investigators. Nevertheless an examination was made which showed that the aircraft struck the southwest slope of Elk Mountain at approximately the 10,822 feet level and the wreckage was scattered approximately 1500 feet beyond. The of the markings on the slope at the point of initial impact indicate that the aircraft was in a horizontal attitude.

There was a discrepancy between the testimony of the airline officials and the ALPA representatives as to the actual number of propeller marks observed on the ground. The airline personnel stated that they observed three propeller marks on either side, while the ALPA representatives stated that they noticed four propeller marks on the left side and three propeller marks on the right side. The difference between propeller marks is also in dispute inasmuch as the ALPA representatives state that there was considerably greater distance between the first mark and the last three marks on the left side and that the marks on the right were similar to the last three marks on the left side. Also there was observed by the Investigators on the mountain, a difference between the two propellers, particularly in the manner in which the blades were best or broken. One blade was broken forward on one propeller and backward on the other.

While it was impossible to make a detailed examination of the *** it should be done at a later date. The local *** testify that the meet favorable time to conduct further examination would be around June 15, in arrangement was made at the hearing thereby this office and *** will take *** action at the earliest possible time.

***

RECOMMENDATION NO. 1.

(RE: UAL Accident, Elk Mountain, Wyo. 1-31-46)

Effective as of August 22, 1946, the Board adopted a Special Civil Air Regulation, Serial No. 323-A, which roads as follows:

"Notwithstanding the provisions of *** 61.5140(a), 61.5141(b), 61.5150(a), and 61.5151(b), any first pilot who on or subsequent to December 7, 1941, was qualified as such and as competent over a regular or alternate route and who has been employed as first pilot in military air transport operations will be considered competent over such route after completing over the route eight (a) one one-way trip as first pilot accompanied by a check pilot or (b) two one-way trips as second pilot.

"This regulation shall terminate March 1, 1946."

During the investigation and subsequent hearing on the above-mentioned accident it was established that Captain Briggs had recently returned from three and a half years of military service and that he had complied with this regulation inasmuch as he had completed three round trips over the route on which the accident occurred. Irrespective of the number of trips, no one was made responsible for checking his qualifications along the route. In other wards, although he made the necessary trips, no one could certify as to his familiarisation with the route procedures or with the terrain along the routs. It is therefore believed that the scope of those regulations should be enlarged and that before any pilot is qualified for route competency he should be certified by the company by whom he is employed and a statement made that he had complied with the regulations and that the company is convinced from actual check that the pilot is fully qualified. It is also believed that this policy should be adopted when issuing an original route competency.

RECOMMENDATION NO. 2.

(RE: UAL Accident, Elk Mountain, Wyoming - 1-31-46)

The preparation of a flight plan includes the altitude of intended flight along the route between radio fixes. Usually those specified altitudes are not less than the minimum instrument altitudes. It is believed that to require on all flights dispatched by scheduled air carrier that a 1000-feet clearance of all obstacles within the airways or within 10 miles either side of the authorised route would not cause undue hardship. This should be required of all flights dispatched in accordance with instrument or contact flight rules and regardless of whether they are conducted day or night.

It is therefore recommended that Civil Air Regulations 61.740, 61.7400, 61.7401 and 61.741 be substituted with a suggested change in altitude requirement, as follows: Flight Altitude Rules: Except during takeoff, landing and final approaches, or when operating in accordance with specific procedures by definite localities approved by the Administrator, no scheduled air carrier aircraft shall be flown at an altitude less than 1000 feet above the highest obstacle located within its prescribed airways, or if there he no airways, within 10 miles on either side of the center of the authorised route. In the event there is a deviation from the prescribed airway or authorised route no scheduled air carrier aircraft shall be flown at an altitude of less than 1000 feet above the highest obstacle located within a horizontal distance of 10 miles within the intended track to be flown.

Had such a provision been in the regulation it is probable that the American Airlines accident at Marion, Virginia, the PCA accident at Morgantown, West Virginia and the UAL accident at Elk Mountain, Wyoming would not have occurred. A search of our accident records of scheduled six carrier would be very enlightening on the subject.

It is recommended that immediate consideration to given to this suggestion.

RECOMMENDATION NO. 3.

That a non-directional radio (for homing) be installed at the intersection of any pair of airways where higher terrain exists off the airway and on the airway proper.

FOOT NOTE:

All times referred to herein are Mountain Standard and are based on a 24-hour clock.