Lockheed L-1049 Super Constellation

The Board determines the probable cause of this accident to be the maneuvering of the aircraft in a manner that caused it to develop an excessive rate of sink while in the turn to final approach.

Loss of control on short final due to windshear.

In spite of an exhaustive investigation it was not possible to determine the actual cause. However, the probable cause was considered to be pilot error in descending below the minimum altitude on final approach. Aircrew fatigue was considered to be a contributing factor.

The Board determines that the probable cause of this accident was an unwanted propeller reversal at a low altitude occurring immediately after takeoff. A contributing factor was the inadequate overhaul procedure employed by the propeller manufacturer.

The accident occurred owing to premature descent caused by the pilot's failure to allow himself a suitable margin for:
- altered flight course and
- shortage of navigational facilities in the area.
It was also reported that the pilot turned northwest on reaching position Tango/2, instead of turning at Barranquilla, and flew towards a wrong position 45 miles from the Riohacha intersection, having failed to take this discrepancy into account in calculating his distance from Maracaibo. It is very likely that the pilot, when reporting 35 miles from Maracaibo, had seen the Carrasquero lights and the surrounding gas flares, through a thin layer of cloud below and believed they were the lights of Maracaibo. The pilot had no way of definitely determining his position in the area, and, therefore, ought to have taken greater precaution against descent at a mistaken location. His best alternative should have been to remain at a safer altitude until (1) he sighted the Maracaibo lights (not the glare), or (2) obtained oscillation of the radio compass needle over Maracaibo.

The crew continued the approach below the minimum safe altitude, maybe following a wrong altimeter setting.

On the basis of the evidence available and the investigation of possible serious threats to safety, the Board cannot establish the cause of the accident with certainty. Moreover, investigation of the possibility that the cause of the accident may have been a bomb explosion has yielded no conclusive facts to support such a hypothesis. The statements in the press to this effect have either been based on misunderstandings or else were tendentious. On the other hand, the Board attributes a high degree of probability to hypothesis that the cause of the accident is related to 'overspeeding' of one of the outboard propellers resulting from oil pollution after a gear had been damaged when the supercharger of the corresponding engine was accelerated (shifted). This probably took place close to the time of the accident. The overspeeding of the propeller, owing to the obstruction of metal particles in the regulator valves may have been such as to cause the propeller pitch to decrease and the propeller could not be feathered. The condition might provoke a flight disturbance which could be corrected only by prompt and powerful handling of aileron and rudder controls. in view of the rapidity with which this defect develops and taking into account that recognition of the nature of this malfunction requires a certain time, it is not always possible for the crew to intervene early enough to restore conditions of controlled flight. With respect to the presumed cause of the accident the Board has no grounds to suppose that the occurrence of the presumed malfunction might be attributable to neglect on the part of maintenance personnel or to incorrect measures taken by the crew or that the crew had been at fault in piloting the aircraft after the malfunction had occurred.