File No. 1-0067 |
CIVIL AERONAUTICS BOARD |
ACCIDENT INVESTIGATION REPORT |
Adopted: April 27, 1948 Released: April 26, 1948 |
SLICK AIRWAYS, INC., NEAR HANKSVILLE, UTAH, AUGUST 21, 1947 |
At approximately 0611, * August 21, 1947, a Curtiss-Wright Commando airplane, Model C-46E, NC-59488, owned and operated by Slick Airways, Inc., a noncertificated air freight carrier, crashed into a ridge of the Blue Bell Knoll Mountain, 40 miles southwest of Hanksville, Utah, at an altitude of approximately 10,000 feet. The occupants, Marvin George Vaughan, captain; Robert F. Humes, first officer; and Herbert V. Preeg, a non-revenue passenger, were killed. The aircraft was destroyed. |
The flight originated at the Willow Run Airport, Ypsilanti, Michigan, August 20, 1947, with its destination, Burbank, California. The first scheduled landing was made at Denver, Colorado, where the crew was changed. Captain Vaughan and First Officer Humes took over, departing from Denver at 0406. Their flight plan specified that they would proceed in accordance with visual flight rules at an altitude of 14,000 feet to Eagle, Colorado; 12,000 feet to Grand Junction, Colorado; 10,000 feet to St. George, Utah; and 8,000 feet to Burbank, California. The proposed air speed was 180 miles per hour and the time en route was computed to be 4 hours and 40 minutes. |
The flight proceeded normally, reporting at 0447 over the Eagle radio range station at 14,000 feet. At 0552, they reported over the Grand Junction radio range station, stating that they were at 12,000 feet and descending to 10,000 feet. They estimated their arrival over Hanksville, Utah, 320 miles from Denver, to be 0556. The flight reported over Hanksville at 0558, stating that they were at 10,000 feet and that they would arrive over Bryce Canyon at 0627. This transmission was received loud and clear, and no indication was given that any mechanical trouble was being experienced. About this time a CAA communicator on duty at Hanksville observed the aircraft flying between the radio range station and Mt. Ellen, located approximately 19 miles south-southwest of the range station. He stated that the aircraft appeared to be flying normally, and was below a layer of clouds. Approximately 12 minutes later the aircraft crashed into a ridge of the Blue Bell Knell Mountain. According to witnesses in the vicinity, clouds obscured the mountain tops at that time. |
The wreckage was located 100 feet below the mountain ridge at an elevation slightly over 10,000 feet, and on a bearing of 228 degrees, magnetic, from the Hanksville radio range station. The terrain in the vicinity of the accident formed a U-shaped canyon with the opening facing eastward. Investigation disclosed that the aircraft had flown into this canyon through the opening as it progressed on its westerly course. The area is very precipitous and rocky. The airplane had practically disintegrated on impact. Evidence indicated that there had been a flash fire at the time the aircraft struck the ground, however, none of the aircraft structure had burned. There was no evidence of any fire existing prior to the time of impact. The disintegration of the aircraft had been so complete that little could be learned from an examination of the wreckage. Observations of those on the ground and the position reports which were received, however, indicated that the airplane had been flying on course and without any difficulty. |
The airplane had been loaded within its allowable limits; and the aircraft records examined showed that it had been properly maintained, and was in an airworthy condition daring the time of this flight. Dispatching of this flight, in accordance with Slick Airways operational practice, was the duty and responsibility of Captain Vaughan. |
Captain Vaughan had been employed by the Slick Airways since March 1, 1946. He had a total of 6,052 flying hours, 324 of which were instrument flight hours. First Officer Humes had been employed by the Slick Airways since March 11, 1947, and formerly had been a U. S. Army Air Forces pilot. He had a total of 3,826 flying hours, 312 of which were instrument flight hours. Herbert V. Preeg was carried as a non-revenue passenger to permit his obtaining factual data for the writing of a story on air freight. |
It is apparent that the flight had been proceeding on course from Hanksville at 10,000 feet in accordance with visual flight rules. Instrument weather conditions, however, existed at 10,000 feet in the vicinity of the crash, and the terrain which the aircraft struck was above the flight’s cruising altitude. According to the Slick Airways Operations Manual, instrument flight over this particular area should have been conducted at 13,000 feet. Considering all known circumstances -- that the tops of the mountains were obscured by clouds, that the aircraft was observed flying below the clouds, that no mechanical difficulty was reported, and that the airplane was observed flying normally on course -- it is logical to conclude that the airplane was flown into clouds and into terrain above its cruising altitude. |
Upon the basis of all available evidence, the Board determines that the probable cause of this accident was the continuation of the flight into instrument weather conditions over mountainous terrain at an altitude too low to clear the mountains en route. |
BY THE CIVIL AERONAUTICS BOARD: |
/s/ JOSEPH J. O’CONNELL, JR. |
/s/ JOSH LEE |
/s/ HAROLD A. JONES |
Ryan, Vice Chairman, and Branch, Member, did not participate. |
FOOT NOTE: |
* All times noted in this report are Mountain Standard and based on the 24-hour clock. |