Research and Analysis Report

This report was tabled in the Australian Parliament on 23 November 1999

Class G airspace (or uncontrolled airspace) has the lowest level of service and the fewest restrictions on aircraft operations. In Australian Class G airspace, third-party directed traffic information is provided to pilots of aircraft operating under the instrument flight rules.

There have been a number of attempts to change the operation of Class G airspace since its introduction in 1995. As part of the Airspace 2000 program, the Civil Aviation Safety Authority (CASA) decided to conduct a 'Class G demonstration' featuring:

• implementation of a national advisory frequency;
• provision of a conditional radar information service;
• cessation of directed traffic information.

The demonstration commenced on 22 October 1998 in the airspace between Canberra and Ballina below 8,500 ft. An end date was not specified; rather, the Authority intended that the demonstration airspace procedures should be extended throughout Australia in June 1999.

The demonstration was conducted in the highest traffic density area of Class G airspace in Australia. The timing and location of the demonstration placed significant pressures on the Civil Aviation Safety Authority to ensure that consultation, safety analysis and education activities were comprehensively addressed.

Following receipt of over 70 air safety incident reports BASI concluded that a safety deficiency existed and commenced an investigation on 5 November 1998 into the systemic issues associated with the development and operation of the Class G airspace demonstration.

The Bureau identified a number of operational deficiencies that contributed to an increased safety risk for users of the demonstration airspace. Following an interim recommendation issued by BASI on 8 December 1998, the demonstration was terminated by the Authority on 13 December 1998.

In addition to the operational deficiencies already noted, a number of organisational factors adversely affected the ability of CASA to effectively manage the Class G airspace demonstration project. Moreover, the division of roles and responsibilities between CASA and Airservices Australia regarding the design and regulation of airspace was not clearly defined.

Safety deficiencies identified during the course of the investigation formed the basis for safety recommendations developed by BASI. The recommendations called for a review of program management policies and procedures for current and proposed changes to the aviation system; a review of corporate governance issues; and clarification of the roles and responsibilities of respective organisations in relation to the regulation, design and management of airspace to ensure the safety integrity of the aviation system.

A full description of these safety actions can be found in Part 4 of the complete report.

This study provides an overview of accidents involving private aircraft operations between 2001and 2005. With approximately 400,000 flying hours conducted annually, private flying accounts for around a quarter of general aviation activity. Within private operations, rotary-wing activity now contributes about 10 per cent of all hours flown.

The accident rate in private aviation activities generally declined over the five-year study period, but the fatal accident rate for fixed-wing aircraft remained generally stable. There was an apparent increase in the rotary-wing fatal accident rate.

The pattern of accident types showed similarities for both fixed-wing and rotary-wing aircraft. Most accidents can be classified against a small number of accident types: collisions, loss of aircraft control, airframe, and powerplant issues. Additionally, collision accidents and those involving a loss of aircraft control account for most of the fatal accidents.

Differences between fixed-wing and rotary-wing aircraft occurrences are more apparent when accidents are examined by phase of flight. More than half of all fixed-wing accidents occur in the landing phase of flight, but manoeuvring and cruise are among the most common phases of flight for accidents involving rotary-wing aircraft. These phases of flight are also associated with fatal accidents.

There is increasing recognition that methods which proactively monitor airline safety may be useful in preventing air safety occurrences. Proactive rather than reactive safety programs are particularly important, considering the high social and economic costs of airline accidents to the community. However, in the aviation industry, there are currently few formal proactive safety management systems in use, and none that reliably demonstrate the desirable goal of improving safety performance. This paper outlines a new proactive safety method for the airline industry, called INDICATE (Identifying Needed Defences In the Civil Aviation Transport Environment).

INDICATE is an airline self-management safety tool which encourages regular passenger transport operators to critically evaluate and continually improve the strength of their safety system. INDICATE also provides a formal communication channel for airline operators to regularly identify and report current weaknesses in aviation regulations, policies and standards to the Bureau of Air Safety Investigation (BASI), before they result in an accident. A major Australian regional airline is currently trialling INDICATE, so that an evaluation of its effectiveness and application to the wider aviation industry can be established. Preliminary results from this trial are presented.

Controlled flight into terrain (CFIT) has been identified as one of 'aviation's historic killers', claiming the lives of more than 35,000 people since the emergence of civil aviation in the 1920s. The purpose of this report was to provide an overview of CFIT from an international perspective, to examine current and potential CFIT preventative strategies, and to specifically identify those characteristics associated with CFIT in Australia.

A search of the Australian Transport Safety Bureau's (ATSB) aviation safety database identified 25 CFIT accidents and two CFIT incidents in the period 1996 to 2005. General aviation accounted for the greatest proportion of CFIT accidents, fatal accidents and fatalities. Only one CFIT occurrence over the reporting period (VH-TFU, Lockhart River, Queensland, 7 May 2005) involved regular public transport operations, but this accident accounted for nearly one-third of all CFIT fatalities. This highlights the catastrophic impact one CFIT accident involving passenger operations can have.

In line with international experience, nearly two-thirds of CFIT accidents and incidents in Australia occurred in the approach phase of flight, of which half of these were during an instrument approach.

When compared with the total number of accidents recorded by the ATSB over the 10-year period, the results of the study indicate that CFIT in Australia is a rare event. However, when CFIT does occur, the likelihood of it resulting in fatalities is high.

Incapacitation of a pilot due to the effects of a medical condition or a physiological impairment represents a serious potential threat to flight safety. The purpose of this research project was to investigate the prevalence, type, nature and significance of in-flight medical conditions and incapacitation events occurring in civil aviation. A search of the Australian Transport Safety Bureau's accident and incident database was conducted for medical conditions and incapacitation events between 1 January 1975 and 31 March 2006. There were 98 occurrences in which the pilot of the aircraft was incapacitated for medical or physiological reasons (16 accidents, one serious incident and 81 incidents). Such events accounted for only 0.6 of a percentage point of all the occurrences listed in the Australian Transport Safety Bureau's database. The majority of the events occurred in airline operations, with private flying the next most common (22.4 per cent of events). In 10 occurrences (10.2 per cent), the outcome of the event was a fatal accident. All of these accidents involved single-pilot operations, and in the majority of cases, heart attack was the most common cause. The majority (21 per cent) of in-flight medical and incapacitation events in Australian civil pilots for the study period were due to acute gastrointestinal illness (usually food poisoning), a finding consistent with other published studies. The next most common cause was exposure to toxic smoke and fumes on board the aircraft, of which 25 per cent were due to carbon monoxide. The results of this study demonstrate that the risk of a pilot suffering from an in-flight medical condition or incapacitation event is low. However, if the pilot suffers a heart attack the risk of a fatal accident occurring increases. The aeromedical certification process must keep pace with the evolving nature of modern medical science to ensure that the risk of in-flight incapacitation remains low.

Spatial disorientation (SD) is among the most common factors contributing to aviation accidents and incidents, but its true prevalence is difficult to establish. This is because many accidents where SD is cited as a likely factor are fatal, and therefore its role cannot be known with any certainty, but also because in the many instances of SD where an accident doesn't result, it goes unreported.

This study provides a comprehensive explanation of the various types of SD in the aviation environment, and suggest strategies for managing the risk associated with SD events. This report provides an informative overview of the three basic types of SD, and the circumstances under which disorientation might be more likely. These are of value to all pilots, and especially those who conduct flights in instrument conditions or at night under visual flight rules. Single-pilot operations, particularly where an autopilot is not available, face additional risks and the need to identify and manage SD events.

This report also encourages pilots who have experienced SD episodes to share their experiences with their aviation colleagues, either informally, or through magazines, journals and web-based forums. This will serve to encourage a greater awareness of the incidence of SD, and help reduce the stigma that some pilots might associate with these events. As other studies suggest, SD is likely to be encountered by all pilots during the course of a lifetime's flying - whether professional or non-professional, experienced or inexperienced. A more open approach to acknowledging and discussing SD and its various causes will make a valuable contribution to a better understanding of this common human factor.

The 1995 House of Representatives Standing Committee on Transport, Communications and Infrastructure Plane Safe Report (Morris, 1995), found that 'a paucity of information' and 'an absence of safety indicators' were features of the low-capacity RPT sector of the Australian aviation industry. A Preliminary Information Paper published by BASI in 1996 concluded that a range of safety issues warranting further research existed within the regional airline industry. BASI then appointed a research team to comprehensively investigate the level of safety in the regional airline industry.

After a study of safety occurrences in the BASI database and visits to many regional airlines, a safety questionnaire was sent to every member of the regional airline industry. More than 28% of industry members responded to the survey.

The study examined all areas of the regional airlines operations, including cabin safety, flight operations, maintenance, airspace management, regulations and surveillance.

Overall, the results indicated that in 1996-97 the safety health of the industry was good, although some areas for improvement were identified. Ninety-two per cent of respondents rated the safety of their regional airline as adequate or better. On the other hand, 57% of respondents identified reasons for avoiding some regional airlines. The results showed that there was an industry wide awareness of the importance of a good safety culture.

Where a safety deficiency was identified by this study, safety action, in the form of a recommendation or a safety advisory notice, was taken by BASI. A summary of the safety action taken prior to the release of this report is contained in chapter 6.

This study was conducted with the support of the industry and shows that, on the whole, the industry does have a high regard for safety. However, it was found that in some airlines, commercial pressures were a significant factor in many safety deficiencies.

Note: The Bureau recognises that a number of changes have occurred within aspects of the aviation industry between the time the Regional Airlines Safety Study commenced and the release of this report. The findings of the study, as summarised in chapter 5 of this report, are based on the 1996-97 structure and climate of the aviation industry. Every effort has been made to acknowledge relevant changes.

Communication within the air traffic system relies heavily on the verbal interaction between pilots and air traffic controllers (controllers) to ensure the safe and efficient operation of air traffic. The use of standard phraseology and radio telephony procedures, such as readbacks, minimises the opportunity for misinterpretation between pilot and controller.

Some sectors of the industry have raised concerns regarding the use of excess or non-standard phraseology in readbacks on the surface movement control (SMC) frequency, resulting in radio congestion. The purpose of this report was to explore the relationship between excess or nonstandard words in readbacks and its effect on frequency congestion.

A review of the Sydney SMC frequency tapes concluded that most users complied with the readback requirements stipulated in the Aeronautical Information Publication (AIP), with only the occasional radio transmission containing excess or non-standard verbiage. Overall, the tapes identified a high level of compliance with the AIP readback requirements; however, it was noted that the use of pleasantries was commonplace. While these did not appear to affect frequency congestion adversely, in times of high traffic density it seems inappropriate.

This study provides a systematic analysis of the types of human error occurring in Australian civil aviation accidents. It also compares these results against a larger sample of accidents occurring in the United States. Inevitably, all humans make errors. But safety can be enhanced when the number and consequences of these errors are reduced. This paper aims to enhance aviation safety through extending our knowledge of aircrew errors.

While the types of accidents and flying operations varied slightly between Australia and the US, the pattern of aircrew errors were remarkably similar. Skill-based errors were the most prevalent type of aircrew unsafe act, followed by decision errors, violations and perceptual errors in both Australian and US accidents. Skill-based errors were also the most common error type irrespective of the severity of the accident. In Australia, decision errors and violations were more common in fatal accidents.

The trend data indicated that the proportion of accidents associated with skill-based errors did not change over the period studied, but decision errors decreased.

The distribution of unsafe acts across flying operation type indicated that skill-based errors were disproportionately higher in both general aviation and agricultural operations. Charter operations (called on-demand in the US) had a high proportion of violations and decision errors. The pattern of unsafe acts within each type of flying operation was broadly similar for Australian and US accidents.

The study demonstrated that the greatest gains in reducing aviation accidents could be achieved by reducing skill-based errors. Moreover, improvements in aeronautical decision making and the modification of risk-taking behaviour could reduce aviation fatalities. Further study is needed to both identify which particular skills need improving, and to investigate the importance of interactions between the error categories.

Following three breakdown of separation occurrences in the airspace of the Sydney Terminal Area (TMA), the Bureau of Air Safety Investigation (BASI) initiated a systemic investigation into the common factors underlying those occurrences. The investigation commenced on 22 June 1998 and was completed by 31 July 1998. Three further occurrences were identified during the course of the investigation.

The systemic investigation has identified safety deficiencies primarily related to the management of change, and the rate and complexity of change faced by air traffic controllers operating in the Sydney Terminal Control Unit over the last four years. Resolving these management issues will further enhance the safe operation of aircraft in the airspace of the Sydney Terminal area. This report contains nine safety recommendations that have been developed to address identified safety deficiencies.