Macau

The following findings were identified:
Air Traffic Services:
1. ATS was not available at Baucau at the time of the occurrence.
2. There was no procedure in place to provide flight crews of aircraft engaged in non-UN operations with an altimeter subscale setting for Baucau at the time of the occurrence.
Organisational factors:
1. Neither the Lao-based company, nor the Cambodian-based company, sought the consent for the proposed sublease, dated 18 November 2002, and accordingly the inferred sublease had not been finalised.
2. The Cambodian-based company was not the operator of the aircraft for the occurrence flight.
3. The Lao PDR was the State of Registry and State of the Operator.
4. The Lao DCA was responsible for the continued surveillance of the operator to ensure that the required standards of operation were maintained.
5. The operator provided flight crews with inflight CFIT avoidance procedures in its operations manual.
CFIT risk exposure:
1. The planned flight from Macau to Baucau was exposed to moderate risk of a CFIT event, based on historical CFIT data and the Transport Canada simple method of risk analysis.
2. The destination risk factors, type of operation, area of operation, weather conditions, and flight crew non-compliance with published procedures increased the CFIT risk exposure of the planned flight to an above-average level.
3. The consequences of the accident were catastrophic and resulted in loss of human life and damage to property and the environment.
4. Those catastrophic consequences resulted from the flight crew’s disregard of established procedures; that disregard bypassed all the safety criteria and inbuilt risk treatments in the design of those procedures and steadily increased the CFIT risk exposure to an extreme level during the latter stages of the flight.
Significant factors:
1. The flight crew did not comply the published non-precision instrument approach and/or missed approach procedures at Baucau during flight in instrument meteorological conditions.
2. The flight crew conducted user-defined non-precision instrument approaches to runway 14 at Baucau during flight in instrument meteorological conditions.
3. The pilot in command permitted the aircraft to descend below the MDA(H) published on both the Jeppesen and CAD runway 14 instrument approach charts during flight in instrument meteorological conditions.
4. The flight crew did not recognise the increased likelihood and therefore risk of CFIT.
5. The flight crew did not recognise or treat that risk in a timely manner.

The following findings were identified:
1. The accident flight encountered severe icing conditions. The liquid water content and maximum droplet size were beyond the icing certification envelope of FAR/JAR 25 appendix C.
2. TNA's training and rating of aircraft severe icing for this pilots has not been effective and the pilots have not developed a familiarity with the Note, CAUTION and WARNING set forth in Flight Crew Operating Manual and Airplane Flight Manual to adequately perform their duties.
3. After the flight crew detected icing condition and the airframe de-icing system was activated twice, the flight crew did not read the relative Handbook, thereby the procedure was not able to inform the flight crew and to remind them of "be alert to severe icing detection".
4. The "unexpected decrease in speed" indicated by the airspeed indicator is an indication of severe icing.
5. The flight crew did not respond to the severe Icing conditions with pertinent alertness and situation awareness that the aircraft might have encountered conditions which was "outside that for which the aircraft was certificated and might seriously degrade the performance and controllability of the aircraft".
6. The flight crew was too late in detecting the severe icing conditions. After detection, they did not change altitude immediately, nor take other steps required in the Severe Icing Emergency Procedures.
7. The aircraft was in an "unusual or uncontrolled rolling and pitching" state, and a stall occurred thereafter.
8. After the aircraft had developed a stall and an abnormal attitude, the recovery maneuvering did not comply with the operating procedures and techniques for Recovery of Unusual Attitudes. The performance and controllability of the aircraft may have been seriously degraded by then. It cannot be confirmed whether the unusual attitudes of the aircraft could have been recovered if the crew's operation had complied with the relevant procedures and techniques.
9. During the first 25 minutes, the extra drag increased about 100 counts, inducing a speed diminishing about 10 knots.
10. During the airframe de-icing system was intermittently switched off, it is highly probable that residual ice covered on the wings of the aircraft.
11. Four minutes prior to autopilot disengaged, the extra drag increased about 500 counts, and airspeed decayed to 158 knots, and lift-drag ratio loss about 64% rapidly.
12. During the 10s before the roll upset, the longitudinal and lateral stability has been modified by the severe ice accumulated on the wings producing the flow separation. Before autopilot disengaged, the aerodynamic of the aircraft (lift/drag) was degraded of about 40%.

Sudden loss of control by the pilot as a result of being incapacitated by an armed passenger. The police authorities in Macau were in possession of certain evidence which appeared to establish beyond reasonable doubt that the crew of the aircraft were subjected to armed attack by certain passengers shortly after takeoff from Macau for Hong Kong.