Avianca

The accident was due to the faulty procedure on the part of the pilot who made the en route climb from Manizales to San Felix at a low altitude, so that the aircraft became trapped in a canyon and crashed in the San Felix pass at La Aguadita after stalling during a turn at 9,000 feet.

The adoption of a final approach path resulting in a heavy landing during which a major structural failure occurred in the port wing in the immediate vicinity of Station 80 joint caused by the transmission of stresses through the undercarriage in excess of those which would be encountered if the rate of sink of the aircraft at the time of impact had been controlled within the designed maximum of 10 feet per second. The primary responsibility for the safety of an aircraft and its complement is vested in the captain. However, there is evidence of mitigating circumstances in that the errors of judgement that precipitated the disaster reflect some deficiency of knowledge which should have been instilled in the training and flight proficiency checking of the pilots of HK-177. A measure of responsibility for the accident must, therefore, devolve on the supervisory and advisory authorities for the overall conduct of the operation.

The aircraft was not following the assigned route at the time of the accident, maybe due to a navigation error or a malfunction of one or more instruments.

It was determined that the probable cause of the accident was an instrument flight at inadequate altitude. The following factors were considered as contributing:
- The Buenaventura route was not followed,
- Instrument flight which precluded visual means of checking the aircraft's position,
- The pilot did not consider it necessary to check his position by means of El Paso radio beacon,
- Over-confidence on the part of the pilot regarding his knowledge of the route,
- Flight outside the established route or airway
- Unfavorable weather conditions.
As the aircraft crashed on the direct route Condoto - Cali and the said route had not been authorized by the Civil Aeronautics Department, it can be logically assumed that the pilot is solely responsible for this accident since he flew, on instruments, a route which had not been authorized, even for visual flights.

The probable initial cause of the accident was the failure of the pilot to carry out the normal climb-out procedure following take-off from runway 34 on a flight to Bermuda and his having made a turn to the left instead of to the right, thus flying into the mountains instead of turning out to sea.
The possibility of the aircraft having been forced to make a left turn may be disregarded since, from examination of the wreckage, it appears that no mechanical failure occurred.
The procedure to be followed had been duly explained to the crew both at the briefing and in the instructions which were certainly given by the tower. It is pointed out, moreover, that the chart of Lajes in the route manual supplied to the crew clearly shows that all turns must be made towards the Northeast.
The question of a right turn following take-off appears to have been deemed a secondary matter by the crew members who called at the briefing office. They simply established that they had to proceed directly to Ponto Sul in order to avoid a collision with the mountains, the highest point of which reached 7 615 feet.
From the heading presumed to have been flown by the aircraft before it crashed, it is quite apparent that the pilot did, in fact, intend to proceed to Ponto Sul. He appears not to have realized, however, that to do so he had to turn eastward towards the sea and not to the west over the land.
It is necessary to mention that, according to his company, this was the first time that the captain had landed at Lajes and that at Santa Maria, where he had already landed several times, the take-off procedure for flights towards the Northwest in the direction of Bermuda also involves a turn towards the sea. The turn at Santa Maria is made to the left, however, as the airport is located on the extreme west of the island.
The point known as Ponto Sul is shown on the reproduced 1:l 000 000 chart at Fig. 30. Examination of this chart will immediately explain the reason for the adoption in the Azores control area of the standard procedure whereby aircraft are required to fly over this point before proceeding towards Bermuda, in order to avoid the high ground on Terceira, S. Jorge, Pico and Faial Islands.
Since Lajes Airport is located in the extreme Northeast of the Ihla Terceira, the requirement, for reasons of safety, to turn to the east and out to sea in order to avoid the mountains on the island needs no special comment, being obvious in view of the nature of the terrain.

Controlled flight into terrain.