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Although when inspected after the accident, the flight recorder indicated that the automatic pilot had not been in operation at any time during the flight from Salt Lake City, nevertheless consideration was given to the engagement of this device, inadvertently indexed for climb, after the airplane had attained level flight. However, tests conducted by the Douglas Aircraft Company to establish the violence of the pull-up to which the airplane would be subjected in such an event, showed that the acceleration did not exceed 2G. This obviously would not cause failure of either the wing or the tail surfaces.
It is not known whether or not the presence of the first officer and the copilot-trainee in the two pilot seats contributed in any way to the accident. There is at least a possibility that had the captain, with his greater experience, been at the controls, he might have either prevented the accident or minimized the results. This however lies within the realm of speculation.
As a result of this accident it was revealed that the term "properly qualified company personnel", as it appears in Section 61.7802[1] of the Civil Air Regulations, had not been uniformly interpreted. Subsequent to this accident the Administrator made it clear that the interpretation of this Section would render any company employee ineligible to occupy a pilot's seat, or to manipulate the controls of a scheduled air carrier aircraft in flight, unless and until he was listed as a pilot in the Operations Specifications of the company. Any ambiguity in the subject Section would be eliminated by appropriate changes in the language now under consideration by the Board.
Summary of Analysis
The examination of the wreckage points conclusively to a failure in the air of the aircraft's structure. The analysis of the condition and of the type of fractures on the wings and tail surfaces indicated quite definitely that the right stabilizer had failed during a pull-up maneuver and that the wing failure was also consistent with pull-up loads. No indication was found that the failure had been due to any defect of material or workmanship. Furthermore, it was ascertained that the design strength of the stabilizer was such as to require more than a normal force by the pilot to cause failure in a pull-up, provided that the air-load conditions during the pull-up were as anticipated in the design requirements. In view of the above it is concluded that during the subject pull-up unusual and abnormally high air loads prevailed, but the knowledge of their origin and exact nature is limited at the present time.
- ↑ "Section 61.7802 Manipulation of controls. No person, other than a first or second pilot, shall manipulate the controls of an air carrier aircraft while in scheduled flight: Provided, That at the discretion of the first pilot such restrictions shall not apply to authorized inspectors of the Administrator or to properly qualified company personnel or to properly qualified personnel of other air carriers."
