Charter/Taxi (Non Scheduled Revenue Flight)

Controlled flight into terrain after the crew started the descent prematurely. The lack of visibility was considered as a contributing factor.

The reason for the loss of engine power in flight, most likely, was a reduction in the filing of the gasoline due to clogging of fuel filters. The appearance, structure and nature of the impurities found in the fuel on the aircraft were not characteristic of impurities accumulated in the fuel supply system in normal operating conditions. The source of the impurities in aircraft fuel system could not be found.

The following factors were identified:
- At takeoff from Coari Airport, the total weight of the aircraft was 6,414 kg, which means 744 kg over the MTOW,
- On board were 26 passengers including 8 children while the aircraft was certified for 19 passengers,
- The left engine fuel pump was completely burnt during the accident but it could not be determined if it failed during the flight or not,
- The crew was not sufficiently trained for emergency situations,
- Poor work organisation,
- Lack of supervision from the operator concerning crew's decisions before and during flights,
- Poor crew coordination,
- Lack of crew communication,
- Non compliance with management techniques,
- Incomplete execution of the actions provided by the emergency checklist.

Findings as to Causes and Contributing Factors:
1. Contamination on the wings of the aircraft was not fully removed before take-off. It is likely that asymmetric contamination of the wings created a lift differential and a loss of lateral control.
2. Although the operator was not authorized for short take-off and landing (STOL) take-off on this aircraft, the crew conducted a STOL take-off, which reduced the aircraft’s safety margin relative to its stalling speed and minimum control speed.
3. As a result of the loss of lateral control, the slow STOL take-off speed, and the manipulation of the flaps, the aircraft did not remain airborne and veered right, colliding with obstacles beside the ski strip.
Findings as to Risk:
1. The out of phase task requirements regarding the engine vibration isolator assembly, as listed in the operator’s maintenance schedule approval, results in a less than thorough inspection requirement, increasing the likelihood of fatigue cracks remaining undetected.
2. The right engine inboard and top engine mounts had pre-existing fatigue cracks, increasing the risk of catastrophic failure.
Other Findings:
1. The cockpit voice recorder (CVR) contained audio of a previous flight and was not in operation during the occurrence flight. Minimum equipment list (MEL) procedures for logbook entries and placarding were not followed.
2. The Transwest Air Limited safety management system (SMS) did not identify deviations from standard operating procedures.

The contrast between the area covered with snow and the snow-cleared area (the runway) induced the pilots visual sensation about the runway threshold. This caused the crew to miscalculate the touchdown point, causing the aircraft to land too far down the runway.

A loss of engine power due to the crew's inadequate in-flight fuel monitoring.

Findings as to Causes and Contributing Factors:
1. An abbreviated visual approach was conducted at night in instrument meteorological conditions, which resulted in the flight crew’s inability to obtain sufficient visual reference to judge their height above the ground.
2. The flight crew did not monitor pressure altimeter readings or reference the minimum altitude requirements in relation to aircraft position on the approach, resulting in controlled flight into terrain.
3. The pilots had not received training and performance checks for the installed global positioning system (GPS) equipment, and were not fully competent in its use. The attempts at adjusting the settings likely distracted the pilots from maintaining the required track and ground clearance during the final approach.
Findings as to Risk:
1. The precision approach path indicator systems (PAPI) at Cambridge Bay had not been inspected in accordance with the Airport Safety Program Manual. Although calibration of the equipment did not have a bearing on this occurrence, there was an increased risk of aircraft misalignment from the proper glide path, especially during night and reduced visibility conditions.
2. The flight crew’s cross-check of barometric altimeter performance was not sufficient to detect which instrument was inaccurate. As a result, reference was made to a defective altimeter, which increased the risk of controlled flight into terrain.
3. Operators’ maintenance organizations normally do not have access to the troubleshooting information contained in Component Maintenance Instruction Manuals for the Intercontinental Dynamics Corporation altimeters. Therefore, aircraft could be dispatched with damaged instruments with the potential for developing a loss of calibration during flight.
4. The flight was conducted during a period in which the crew’s circadian rhythm cycle could result in cognitive and physical performance degradation unless recognized and managed.