Safety Education Material

When fishing in waters off the Australian coast, fishermen will encounter large trading ships. Unfortunately, sometimes ships and fishing vessels collide. The ATSB has investigated 21 of these collisions since 1990. In two collisions investigated, the skippers of the fishing vessels were trapped in their wheelhouses and drowned when the vessels sank. The investigations have revealed that in almost all the collisions, there were similar factors present which contributed to the accident and precautions had not been taken that may have saved a life or at least aided the search for survivors.

Time and again, fatigue has been a major factor in marine incidents and the collision described below is a perfect example of the effects of fatigue. It is a matter of sheer luck that more fishermen have not been killed as a result of fatigue-related accidents.

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 report can be downloaded from the Neville Committee's website: Train Illumination: An inquiry into some measures proposed to improve train visibility and reduce level crossing accidents(Opens in a new tab/window) can be downloaded from the Neville Committee's website.

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.

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.

The purpose of this publication is to provide an overview of level crossing accident fatalities in Australia. The information provided is based on unpublished data obtained from the Australian Bureau of Statistics but responsibility for the analyses presented here rests solely with the ATSB.

Aircraft depressurisation events are rare, but they can occur with little or no warning. The faster you put on your oxygen mask, the better the chance that you will stay safe and remain capable of helping children and others. Reading this safety bulletin will help ensure that you can recognise and appropriately react to an aircraft depressurisation if one should occur.

Why are aircraft pressurised?

Modern aircraft are designed to fly at high altitudes. (For example, large jet aircraft normally cruise at an altitude of 28,000 – 35,000 ft). This is because aircraft consume less fuel and can fly in relatively smooth air, avoiding bad weather and turbulence. However, the human body is not designed to survive at such high altitudes so the air pressure inside the cabin needs to be controlled.

The air pressure inside the cabin cannot be kept the same as the ambient air pressure at ground level as doing so would put excessive stress on the aircraft. Therefore, air pressure altitude inside the cabin (as measured by the equivalent outside altitude) gradually rises from take-off to a maximum of 8,000 ft during the cruise. During the descent to the destination airport, the cabin pressure altitude is gradually reduced to match the ambient air pressure of the airport. Without a fully functional pressurised cabin, passengers and crew need to use oxygen systems at the altitudes typically attained during cruise.

What is depressurisation?

Depressurisation, also called decompression, is the reduction of atmospheric pressure inside a contained space such as the cabin of a pressurised aircraft.

Since 1970 fatalities resulting from accidents between road vehicles and trains at level crossings have reduced by about 70 per cent. However, recently there has been an increasing number of accidents involving heavy road vehicles.

Between April 2006 and December 2007, the ATSB investigated 12 level crossing accidents. Of these 12 accidents, nine have involved heavy road vehicles, four of which have been collisions with long distance passenger trains. In addition, during the same period State authorities have investigated a further three significant accidents between heavy vehicles and passenger trains.

These accidents have cost the lives of 19 people, 13 on board the trains and six occupants of the road vehicles. In addition, over 60 people have been injured and the damage bill is estimated at well over $100 million.

Although fatalities and injuries resulting from accidents at railway level crossings are only a small proportion of the total fatalities and injuries that occur on Australian roads each year, railway level crossing accidents, particularly when they involve heavy road vehicles, have the potential to be catastrophic.

Heavy road vehicles such as road-trains and larger freight trains have become the norm in Australia for the good reason that they are an efficient way to transport goods over long distances between our metropolitan and regional centres. However, with the increased size comes an increased consequence in the event of a level crossing collision. It used to be somewhat rare to hear of a train derailing or of significant casualties on board the train as a result of a collision with a road vehicle. This is not the case today.

Some recent accidents have involved significant loss of life, the worst case being the tragic accident at Kerang when a semi-trailer collided with a Melbourne-bound passenger train on 5 June 2007. Eleven people were killed and 20 injured in this accident.

Another major collision between a B double truck and a freight train occurred at Lismore, Victoria on 25 May 2006. This accident resulted in the death of the truck driver and an estimated damage bill in excess of $30 million.

Maintenance is essential to aviation safety, yet improper maintenance contributes to a significant proportion of aviation accidents and incidents. This is because a small percentage of maintenance tasks are performed incorrectly or are omitted due to human error. Examples include parts installed incorrectly, missing parts, and the omission of necessary checks. While precise statistics are unavailable, it is likely that the great majority of maintenance errors are inconsequential, however, a small proportion present significant safety threats. In comparison to many other threats to aviation safety, the mistakes of maintenance personnel can be more difficult to detect, and have the potential to remain latent, affecting the safe operation of aircraft for longer periods of time.

While acknowledging that maintenance personnel are responsible for their actions, it must also be recognised that, in many cases, the errors of maintenance technicians are the visible manifestation of problems with roots deep in the organisation. A careful examination of each error, combined with a preparedness to inquire into why the error occurred, can help to identify underlying organisational problems. Effective countermeasures to maintenance error require a systemic approach, not only towards issues at the level of the technician and their work environment, but also to organisational factors such as procedures, task scheduling and training. Some countermeasures to the threat of maintenance error are directed at reducing the probability of error through improvements to training, equipment, the work environment and other conditions. A second, complementary, approach is to acknowledge that despite the best efforts, it is not possible to eliminate all maintenance errors, and countermeasures must be put in place to make systems more resilient to those residual maintenance errors that are not prevented.

Aviation organisations are increasingly introducing safety management systems (SMS) that go beyond legal compliance with rules and regulations, and instead emphasise continual improvement through the identification of hazards and the management of risk. The activities involved in managing the risk of maintenance error can be appropriately included within the SMS approach. Key activities include internal incident reporting and investigation systems, human factors awareness for maintenance personnel, and the continual identification and treatment of uncontrolled risks.

On 20 February 2009, this report was updated to include a list of resources and further reading on page 34.

This information bulletin is designed for cabin crew and will supplement your airline's cabin crew emergency procedures manual and should enhance your knowledge about what can occur during an aircraft depressurisation.

Why are aircraft pressurised?

Modern aircraft are designed to fly at high altitudes. For example, a Boeing 747 aircraft normally cruises at an altitude of 28,000 – 35,000 ft. This is because aircraft consume less fuel and fly in relatively smooth air, avoiding bad weather and turbulence. However, the human body is not designed to survive at such high altitudes so the air pressure inside the cabin must be controlled.

The air pressure inside the cabin cannot usually be kept the same as the ambient air pressure at ground level as doing so would put excessive stress on the aircraft fuselage. Therefore, the cabin air pressure altitude (as measured by the equivalent outside altitude) gradually rises from take-off to a maximum of 8,000 ft during the cruise. During the descent to the destination airport, the cabin pressure altitude is gradually reduced to match the ambient air pressure of the airport. Without a fully functional pressurised cabin, passengers and crew need to use oxygen systems at the altitudes typically attained during cruise.  

What is depressurisation?

Depressurisation, also called decompression, is the reduction of atmospheric pressure inside a contained space such as the cabin of a pressurised aircraft.