Boeing 737-200

The following factors were reported:
- Poor approach planning,
- Lack of crew coordination,
- The captain failed to initiate a go-around procedure while the aircraft was unstable and not properly aligned,
- Wrong approach configuration,
- Lack of visibility due to poor weather conditions.

The accident occurred by reason of a grave error on the part of the Pilot-in-Command in not adhering to the operational flight plan and ILS let down chart and not realizing that his early descent to 10,000 feet and turning right for outbound leg without reporting overhead VOR would result in loss of time reference and as such misplace him in the hilly terrain. The Pilot-in-Command's action may have been influenced by his extreme familiarity with the terrain.

A loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide.

Loss of control upon landing after being hijacked.

Failure of the fuel pump control shaft because of improper machining by the repair facility during maintenance modification of the pump and improper procedures during overhaul of the nose landing gear.

Deficiencies in flightcrew coordination, their failure to adequately prepare for and properly execute the unk loc runway 14 non precision approach and their subsequent premature descent.

Failure of the operator's maintenance personnel to detect an electrical wire which had chafed against a hydraulic line and which eventually arced causing a leak in the hydraulic line and subsequent fire and hydraulic system failure. In addition, previous wear of check valves in the backup hydraulic systems prevented the airplane from stopping on the runway. A contributing factor was the airplane manufacturer's inadequate guidance for maintaining the hydraulic components.

It was determined that the collision with the ground was the consequence of a controlled flight into terrain after the crew failed to follow the proper departure route and published procedure.
The following contributing factors were reported:
- Poor flight preparation,
- The crew failed to follow the departure route from runway 03 and initiated a turn to the left, a procedure valid for runway 21 departure onl. After takeoff from runway 03, crew must turn to the right over the sea,
- Poor crew coordination,
- The crew failed to follow the pre-takeoff checklist,
- Poor visibility due to the night.

A. Human Factor
1) Physiological aspect - Did not contribute to the accident.
2) Psychological aspect - The following psychological variables contributed to the accident:
a) Misleading perception - In the reading of the plan and incorrect heading insertion by the commander.
b) Reinforcement - In the reading and incorrect heading insertion by the co-pilot and heading conference placed by the commander.
c) Marginal attention and level of attention - The non-recognition of conditions that would mean being far from the objective: request for "VHF bridge" when other aircraft were talking normally with the Control; "reception" of commercial stations, and non-receipt of destination NDB, etc.
d) Predisposition - Maintaining the urge to go to the established objective (Belém).
e) Predisposition duration - Maintenance of FL040 for a long time.
f) Reinforcement of predisposition - Reception of boundaries when selecting Belem's radio frequencies.
g) Attention Fixing - Permanent search for headings, radio contacts or river contours, as an alternative, to reach the fixed goal.
h) Blocks - Delays in identifying the initial headings error and plotting itself in navigation.
i) Geographical position error.
B. Material Factor - Did not contribute to the accident.
C. Operational Factor
1) Poor supervision - Inadequate graphical representation of the Computer Flight Plan.
2) Poor cockpit coordination - No supervision of cockpit activities. Actions were not supervised, but imitated.
3) Poor support staff - Lack of radio contact by the operator's Flight Coordination with the aircraft in flight, after the significant landing delay in Belém, thus breaking the chain of events of the accident.
4) Pilot aspect characterized by environmental influence - Difficulties of visualization due to sunset and dry fog: Radio aid markings received from great distances, originating from the ionospheric propagation of electromagnetic waves.
5) Pilot aspect characterized by poor planning - Lack of route letters to cross the flight plan information.
6) Pilot aspect characterized by poor judgment - Inadequate evaluation and use of radio-navigation equipment, resulting in the pursuit of markings without causing tuning and identification.
7) Pilot aspect characterized by other operational factors - Operational doctrine firming.