Although the operator installed an enhanced ground proximity warning system (EGPWS) and traffic alert and collision avoidance system (TCAS) on VH-NGA in August 2009, it did not provide relevant flight crew with formal training on using these systems, or incorporate relevant changes into the aircraft’s emergency procedures checklists.
The operator’s application of its fatigue risk management system overemphasised the importance of scores obtained from a bio-mathematical model of fatigue (BMMF), and it did not have the appropriate expertise to understand the limitations and assumptions associated with the model. Overall, the operator did not have sufficient risk controls in addition to the BMMF to manage the duration and timing of duty, rest and standby periods.
Although the operator provided its flight crew with basic awareness training in crew resource management (CRM), it was limited in nature and did not ensure flight crew were provided with sufficient case studies and practical experience in applying relevant CRM techniques.
The operator’s risk controls did not provide assurance that the occupants on an air ambulance aircraft would be able to effectively respond in the event of a ditching or similar emergency. Specific examples included:
The operator and air ambulance provider did not have a structured process in place to conduct pre-flight risk assessments for air ambulance tasks, nor was there any regulatory requirement for such a process.
The operator’s risk controls did not provide assurance that the operator’s Westwind pilots would conduct adequate in-flight fuel management and related activities during flights to remote islands or isolated aerodromes. Limitations included:
The operator’s Westwind pilots generally used a conservative approach to fuel planning, and the operator placed no restrictions on the amount of fuel that pilots uploaded. However, the operator’s risk controls did not provide assurance that there would be sufficient fuel on board flights to remote islands or isolated aerodromes. Limitations included:
Bow Singapore’s planned maintenance system for the steering gear did not include or contain any schedules for detailed inspections or parts replacement.
While there has been significant enhancements in the tracking of commercial aircraft in recent years there are some limitations to the improvements. The ICAO mandated 15-minute position tracking interval for existing aircraft may not reduce a potential search area enough to ensure that survivors and wreckage are located within a reasonable timeframe.
There is relatively limited public and official information available about the process and outcomes of some searches. It is not an explicit part of the ICAO Annex 13 guidelines for inclusion in an accident investigation report. Similarly there is no Annex 12 requirement to publish or analyse search information. This limits the ability for researchers to determine the factors that help or hinder a search.
There was an identified gap in the knowledge of track maintenance personnel that was probably the result of deficiencies in training and development. In addition, network standards for the assessment of track lateral stability, including creep management, provided limited information and tools for maintenance personnel.
There was no supplementary system of inspection that was effective in identifying rail creep in jointed track. The network placed a high reliance on the asset management system to initiate closer inspection of track potentially affected by creep.
Asset management systems used to identify problematic levels of rail creep did not correct for fixed points between creep monuments.
Asset management systems that were used to identify problematic levels of rail creep did not evaluate nor assess cumulative creep.
Classification of parachuting operations in the private category did not provide comparable risk controls to other similar aviation activities that involve the carriage of the general public for payment.
It was likely that the parachutists on the accident flight, as well as those that had participated in previous flights, were not secured to the single-point restraints that were fitted to VH-FRT. While research indicates that single-point restraints provide limited protection when compared to dual-point restraints, they do reduce the risk of load shift following an in-flight upset, which can lead to aircraft controllability issues.
Research has identified that rear‑facing occupants of parachuting aircraft have a higher chance of survival when secured by dual-point restraints, rather than the standard single-point restraints that were generally fitted to Australian parachuting aircraft.
Some Cessna 206 parachuting aircraft, including VH-FRT, had their flight control systems modified without an appropriate maintenance procedure or approval. That increased the risk of flight control obstruction.
Despite being categorised as mandatory for the pilot’s seat by the aircraft manufacturer, a secondary seat stop modification designed to prevent uncommanded rearward pilot seat movement and potential loss of control was not fitted to VH-FRT, nor was it required to be under United States or Australian regulations.
The inspection regime to identify rail fractures was ineffective for the condition of this track.
