Douglas DC-8

The following findings were reported:
1. The organisational structure for the deployment team was ill-defined and fragmented.
2. Deployment maintenance personnel were not qualified or authorised to perform the function of releasing the aircraft as being fit to fly.
3. The release of the aircraft as being fit to fly was delegated to non-practising Aircraft Maintenance Engineers whose primary function was to operate the aircraft as flight crew members.
4. The aircraft was signed-off as fit for flight, in an unairworthy condition, by the operating flight engineer who had no involvement in the aircraft servicing.
5. The #2 and #4 tyre pressures were below the minimum for flight dispatch. Other tyres may also have been below minimum pressures.
6. Maintenance personnel were aware of the low tyre pressures but failed to rectify the faults.
7. The mechanic altered the only record of the actual low pressures, measured by the avionics specialist on 7 July, four days before the accident.
8. There was no evidence that the tyre pressures had been checked, using a tyre pressure gauge, after 7 July.
9. The lead mechanic was aware of the low tyre pressures.
10. The persons who were aware of the low pressures had insufficient knowledge of the hazards of operating at low tyre pressures.
11. The project manager was aware of a low tyre pressure but was not qualified to assess its importance.
12. The project manager was responsible for the aircraft schedule and directed that the aircraft depart without servicing the tyre.
13. The lead mechanic who was aware of the requirement for, and had requested nitrogen for tyre servicing, did not countermand the decision of the project manager.
14. There was no evidence to indicate that this flight crew were ever informed of the low tyre pressures.
15. The aircraft departed the ramp in an unairworthy condition.
16. During the taxi from the ramp to the runway, the transfer of the load from the under-inflated #2 tyre to #1 tyre on the same axle, resulted in over deflection, over-heating and structural weakening of the #1 tyre.
17. The #1 tyre failed very early on the take-off roll due to degeneration of the structure, caused by over-deflection.
18. The #2 tyre failed almost immediately after #1 due to over-deflection and rapid overheating when the load was transferred from the #1 tyre.
19. The #2 wheel stopped rotating for reasons not established. Friction between the wheel/brake assembly and the runway generated sufficient heat to raise the temperature of tyre remnants above that required for a tyre fire to be self-sustaining. Rubber remnants ignited during the take-off roll.
20. Numbers 1 and 2 wheels were severely damaged and at least one piece of #1 wheel rim struck the airframe, becoming embedded in the left flap.
21. The crew were aware of unusual symptoms early and throughout the takeoff roll; the captain continued the take-off.
22. The aircraft was not equipped with warning systems which would have provided the flight crew with adequate information on which to make a decision to reject the take-off after tyre(s) failure.
23. The captain did not receive sufficient cues to convince him that a rejected take-off was warranted.
24. The crew retracted the gear, consistent with company procedures, and burning rubber was brought into close proximity with hydraulic and electrical system components.
25. The evidence indicates that the wheel well fire involved tyres, hydraulic fluid, magnesium alloy and fuel. The fuel was probably introduced as a result of "burn through" of the centre fuel tank.
26. Fire within the wheel wells spread and intensified until the cabin floor was breached and control systems were disabled.
27. The fuel increased the intensity of the fire until, shortly before impact, airframe structural integrity was lost.
28. Tyre characteristics and performance are not adequately addressed during training and licensing of both flight crews and technical personnel.
29. The aircraft operator's tyre inflation pressures did not accurately reflect what was contained in the aircraft manufacturer's maintenance manual.
30. The operator's maintenance and operating documentation for the DC-8 does not contain adequate information for the proper maintenance and operation of aircraft tyres.

Improper preflight planning/preparation, in that the flight engineer miscalculated (misjudged) the aircraft's gross weight by 100,000 lbs and provided the captain with improper takeoff speeds; and improper supervision by the captain. Factors related to the accident were: improper trim setting provided to the captain by the flight engineer, inadequate monitoring of the performance data by the first officer, and the company management's inadequate surveillance of the operation.

Wrong approach configuration on part of the crew who landed the aircraft too far down the runway, reducing the landing distance available. At the time of the accident, the runway was wet, which was considered as a contributing factor.

The Commission determines:
a) That as a result of the captain's glaring carelessness and recklessness the aircraft was flown below the published minimum altitudes during the approach and consequently collided with a tree.
b) As underlying factor in the accident was the failure of SLM's operational management to observe the pertinent regulations as well as the procedures prescribed in the SLM Operations Manual concerning qualification and certification during recruitment and employment of the crew members furnished by ACI.

It was determined that one of the engine failed and caught fire shortly after rotation for unknown reasons. The crew already abandoned a first attempt to takeoff few minutes earlier for similar reasons.

The Canadian Aviation Safety Board was unable to determine the exact sequence of events which led to this accident. The Board believes, however, that the weight of evidence supports the conclusion that, shortly after lift-off, the aircraft experienced an increase in drag and reduction in lift which resulted in a stall at low altitude from which recovery was not possible. The most probable cause of the stall was determined to be ice contamination on the leading edge and upper surface of the wing. Other possible factors such as a loss of thrust from the number four engine and inappropriate take-off reference speeds may have compounded the effects of the contamination.

The incorrect position of the horizontal stabilizer in relation to the aircraft's centre of gravity, which prevented the aircraft from reaching rotation and lift-off speed within the runway distance available. The following contributing factors were reported:
- Clearance of the aircraft from Quito was done incorrectly, since the MTOW permissible for the existing runway, wind and temperature conditions, the real take-off weight, the useful load distribution and the position of the aircraft's centre of gravity were not determined,
- The crew's state of mind may have been a contributing factor in the accident. It is assumed that it prevented the crew from concentrating on all aspects of the operation they were performing.

Wrong approach configuration on part of the crew who landed too far down the runway. In such conditions, the landing distance available was insufficient. The crew failed to initiate a go around. Poor weather conditions and wet runway surface conditions were considered as contributing factors.

The flight crew's failure to follow procedural checklist requirements and to detect and correct a mistrimmed stabilizer before the aircraft became uncontrollable. Contributing to the accident was the captain allowing the second officer, who was not qualified to act as a pilot, to occupy the seat of the first officer and to conduct the take-off.

The explosion of the air brake bottle damaging 13 hydraulic system tubes and 2 emergency air brake system tubes, some of which resulted in the failure of extension of flaps and a loss of normal as well as emergency wheel braking, thus increasing the roll after touchdown distance to a value greater than available runway and stop way length. These factors prevented the captain from stopping the aircraft within the runway and stop way confines.