During 2004 the Neville Committee conducted an Inquiry into Train Illumination.
The Committee tabled its report, Train Illumination: An inquiry into some measures proposed to improve train visibility and reduce level crossing accidents, on 24 June 2004.
The Government Response to the report, which was coordinated by the Australian Transport Safety Bureau, was tabled in Parliament on 7 December 2005 and is available below.
This report presents data concerning Australian aviation activity, the aviation industry, aviation accidents and incidents and highlights broad trends and developments in aviation safety. The data are presented graphically in time series figures. Data on aviation accidents and incidents were collected from the ATSB's aviation database. Data concerning aviation activity, the aviation industry, accidents and specific incident types were collected from three main sources: the Bureau of Transport and Regional Economics, part of the Department of Transport and Regional Services, the Civil Aviation Safety Authority and Airservices Australia.
The aim of this study was to provide information to the flying community about issues that have the potential to affect safety in the hope that increased knowledge and insight could lead to improved safety. The ATSB distributed the 'Aviation Industry Safety Survey' in November 2003 to 5,000 commercial pilots throughout Australia. Pilots were asked to respond to a series of questions regarding their flying experiences in the 12 months prior to receiving the survey. The survey consisted of two sections: Part A and Part B. Information about Part A has been reported in the ATSB Aviation Safety Survey - Safety Climate Factors (2004) publication. The analysis of one question (relating to common flying errors by respondents) in Part B was reported in the ATSB Aviation Safety Survey - Common Flying Errors (2004) publication. This report addressed six questions (39 to 44) in Part B of the survey (reproduced in Attachment A). Information concerning pilot age, highest licence held, hours flown, type of operation and aircraft details were obtained from the survey responses.
The twin-engine power loss accidents were analysed to identify the types of accidents that occurred. Ten of the 11 fatal accidents subsequent to a power loss in twin-engine aircraft were the result of an in-flight loss of control. In contrast, the majority of non-fatal accidents subsequent to a power loss were primarily the result of degraded aircraft performance and resulted in aircraft being forced landed. When a twin-engine aircraft sustains a loss of power, the resulting power output can produce a power condition that is either asymmetric or non-asymmetric. The twin-engine power loss accidents were grouped based on whether the aircraft was being powered asymmetrically or non-asymmetrically when the accident occurred.
Weather-related general aviation accidents remain one of the most significant causes for concern in aviation safety. Previous studies into the factors associated with weather-related general aviation occurrences have typically compared accident and non-accident cases. In contrast, this study does not concentrate on occurrence outcome. Instead, the emphasis is on the different behaviours that pilots exhibit in the face of adverse weather and, by inference, on the decision-making processes that underlie those behaviours. The work of this study is based on a set of 491 aviation accident and incident reports drawn from the Australian Transport Safety Bureau (ATSB) occurrence database. The study compares three groups of pilots who differed in their response to adverse weather conditions encountered during their flight.
Night Vision Goggles (NVGs) are binocular devices that enhance unaided night vision for pilots. Typically, NVGs are mounted on a pilot's helmet. This position enables pilots to look through the goggles outside the cockpit or under the goggles at flight instruments. By enabling the pilot to see in the dark, NVGs have the potential to improve the safety of visual flight at night. In most conditions, night vision goggles provide pilots with a significant increase in the quality of visual information compared with unaided night vision. They allow the pilot to see the horizon, objects, terrain and weather more easily. Furthermore, they assist the pilot to maintain spatial orientation, to avoid hazards such as inadvertent Instrument Meteorological Conditions (IMC) entry, and to visually navigate.
The determination of blood ethanol concentration in a deceased pilot is an important part of the accident investigation. The finding of an elevated blood alcohol level in such a case may have significant implications, both medico-legal and social. It is therefore important to ensure that the finding of an elevated blood alcohol concentration is valid.
It is known that micro-organisms involved in the process of putrefaction after death can produce alcohol, usually a mixture of ethanol and other volatile substances. This process occurs when a body is not refrigerated soon after death and is hastened by environmental conditions such as high temperatures and when the body has been traumatised.
Older methods of analysis could not distinguish between ethanol and mixtures of other volatile compounds. Current methodology (gas chromatography) can isolate ethanol and identify other substances.
There is a range of specimens in which ethanol can be measured. Their suitability for analysis can be determined by microbiological studies although this would not be routinely performed in most laboratories.
Medico-legal and forensic implications are associated with a 'blood alcohol concentration'.49 It therefore seems most useful to measure the ethanol level in a specimen of blood, but this may not always be available depending on the state of the body. Vitreous is the next specimen of choice, and valid conclusions regarding the ingestion of alcohol can usually be made based on the results of its analysis.
Urine analysis may also be helpful, particularly in conjunction with blood and vitreous. Comparison of levels of these three specimens is probably the ideal means of interpreting blood alcohol concentrations. If none of these specimens is available, resort can be made to other organ and tissue samples but there are difficulties in both methodology and interpretation of results relating any alcohol present to ingested ethanol.
Ethanol in gastric contents generally indicates recent ingestion, but the rapid absorption of ethanol and post-mortem diffusion from the stomach may limit the usefulness of analysis of gastric contents.
The presence of volatile compounds in addition to ethanol (seen by gas chromatography methods) may suggest post-mortem production by micro-organisms but also needs to be interpreted cautiously.
It is possible to measure parameters which are associated with or indicate ethanol consumption. These are qualitative only and do not enable the blood ethanol concentration to be calculated or estimated. They have applications in a clinical setting where they address the issue of alcohol consumption in previous days. This is not usually the main issue in a fatal aviation accident investigation, where the "bottle to throttle" rule applies, and the issue is what factors were influencing the pilot's capacity to fly the aircraft. Two of these measurements, ethyl glucuronide and the 5-HTOL: 5-HIAA may have some application in the future of fatal aviation accident investigation, but they are not currently performed routinely.
In Australia, mountain waves are commonly experienced over and to the lee of mountain ranges in the south-east of the continent. They often appear in the strong westerly wind flows on the east coast in late winter and early spring.
Mountain waves are a different phenomena to the mechanical turbulence found in the lee of mountain ranges, and can exist as a smooth undulating airflow or may contain clear air turbulence in the form of breaking waves and 'rotors'. Mountain waves are defined as 'severe' when the associated downdrafts exceed 600 ft/min and/or severe turbulence is observed or forecast.
'Breaking waves' and 'rotors' associated with mountain waves are among the more hazardous phenomenon that pilots can experience. Understanding the dynamics of the wind is important in improving aviation safety.
Glider pilots learn to use these mountain waves to their advantage; typically to gain altitude. However, some aircraft have come to grief in those conditions. Encounters have been described as similar to hitting a wall. In 1966, clear air turbulence associated with a mountain wave ripped apart a BOAC Boeing 707 while it flew near Mt. Fuji in Japan. In 1968, a Fairchild F-27B lost parts of its wings and empennage, and in 1992 a Douglas DC-8 lost an engine and wingtip in mountain wave encounters.
Mountain waves are the result of flowing air being forced to rise up the windward side of a mountain barrier, then as a result of certain atmospheric conditions, sinking down the leeward side. This perturbation develops into a series of standing waves downstream from the barrier, and may extend for hundreds of kilometres over clear areas of land and open water.
Mountain waves are likely to form when the following atmospheric conditions are present:
the wind flow at around ridge height is nearly perpendicular to the ridge line and at least 25 kts
the wind speed increases with height
there is a stable layer at around ridge height.
If the wave amplitude is large enough, then the waves become unstable and break, similar to the breaking waves seen in the surf. Within these 'breaking waves', the atmospheric flow becomes turbulent.
The crests of the waves may be identified by the formation of lenticular clouds (lens-shaped), if the air is sufficiently moist. Mountain waves may extend into the stratosphere and become more pronounced as height increases. Some pilots have reported mountain waves at 60,000 feet. The vertical airflow component of a standing wave may exceed 8,000 ft/min.
Rotors or eddies can also be found embedded in mountain waves. Formation of rotors can also occur as a result of down slope winds. Their formation usually occurs where wind speeds change in a wave or where friction slows the wind near to the ground. Often these rotors will be experienced as gusts or windshear. Clouds may also form on the up-flow side of a rotor and dissipate on the down-flow side if the air is sufficiently moist.
Many dangers lie in the effects of mountain waves and associated turbulence on aircraft performance and control. In addition to generating turbulence that has demonstrated sufficient ferocity to significantly damage aircraft or lead to loss of aircraft control, the more prevailing danger to aircraft in the lower levels in Australia seems to be the effect on the climb rate of an aircraft. General aviation aircraft rarely have performance capability sufficient to enable the pilot to overcome the effects of a severe downdraft generated by a mountain wave or the turbulence or windshear generated by a rotor. In 1996, three people were fatally injured when a Cessna 206 encountered lee (mountain) waves. The investigation report concluded, "It is probable that the maximum climb performance of the aircraft was not capable of overcoming the strong downdrafts in the area at the time".
Crossing a mountain barrier into wind also reduces the groundspeed of an aircraft and has the effect of keeping the aircraft in the area of downdraft for longer, while an aircraft flying downwind on the upwind side of a mountain range is likely to initially encounter updrafts as it approaches rising ground. Rotors and turbulence may also affect low level flying operations near hills or trees. In 1999, a Kawasaki KH-4 hit the surface of a lake during spraying operations at 30 feet. The lack of sufficient height to overcome the effects of wind eddies and turbulence was a factor in the accident.
Research into 'braking waves' and 'rotors' or eddies continues but there is no doubt that pilots need to be aware of the phenomenon and take appropriate precautions. Although mountain wave activity is usually forecast reasonably well by the Bureau of Meteorology, many local factors may effect the formation of 'breaking waves' and 'rotors'. When planning a flight a pilot should take note of the winds and the terrain to assess the likelihood of waves and rotors. There may be telltale signs in flight, including the disturbances on water or wheat fields and the formation of clouds, provided there is sufficient moisture for cloud to form.
Prudent flight planning may include allowing for the possibility of significant variations in the aircrafts altitude if updrafts and downdraughts are encountered. A margin of at least the height of the hill or mountain from the surface should be allowed, and consideration given to the need to adopt a manoeuvring airspeed appropriate to the circumstances. Ultimately, it may be preferable for pilots to consider diverting or not flying, rather than risk flying near or over mountainous terrain in strong wind conditions conducive to mountain waves containing 'breaking waves' and 'rotors'.
Further Reading
Bureau of Meteorology. (2007). Manual of Aviation Meteorology. Second Edition, pp 59, 60, 68. Airservices Australia.
Bureau of Air Safety Investigation Journal. (1991, September). Downslope winds are dangerous. BASI Journal, 9, pp 38-39.
Jorgensen, K. (undated). Mountain flying: A guide to helicopter flying in mountainous and high altitude areas. Westcourt, QLD: Cranford Publications.
Lester, P. F. (1993). Turbulence: A new perspective for pilots. Englewood, CO: Jeppesen Sanderson.
McCann, Donald W. (2006). Diagnosing and forecasting aircraft turbulence with steepening mountain waves. National Weather Digest, pp 77-92.
New Zealand Civil Aviation Authority (2006), Good Aviation Practice, Mountain Flying booklet.
Welch, John, F. (Ed.). (1995). Van Sickles modern airmanship (7th Ed). New York, NY: McGraw-Hill.
Woods, R. H., & Sweginnis, R. W. (1995). Aircraft accident investigation. Casper, WY: Endeavor Books.
The primary objective of any investigation into an air safety occurrence is the prevention of an accident.
Sometimes an investigation will uncover a safety deficiency in the aviation system and recommendations are made to address the deficiency. At other times the details and circumstance of an accident or incident don't immediately uncover a safety deficiency or even provide immediate answers. However, the occurrence data is collected and stored in the ATSB database and may at some time in the future form part of a wider analysis of safety issues.
A safety deficiency is defined in the Transport Safety Investigation Act 2003 subsection 23(2) as one of the categories of transport safety matters that can be investigated. It is defined as:
Something that occurred that affected, is affecting, or might affect, transport safety.
To identify a deficiency the ATSB first collects information from an investigation or safety (research) study. Then it analyses the data and works with the industry to develop safety recommendations and actions.
Aviation safety deficiencies may be found in many factors and could include one or more of the following:
aircraft or component design
the manufacturing or quality control process
maintenance and/or engineering procedures
regulatory standard, information and advisory documents
operational procedures
Air Traffic Services procedures and documentation
corporate management procedures.
If recommendations are made as a result of a safety deficiency, they are sent to the most appropriate organisation or agency to effect change. This may include the Civil Aviation Safety Authority, Airservices Australia, maintenance and aircraft operators and manufacturers.
