A significant proportion of all occurrences reported to the Australian Transport Safety Bureau (ATSB) involve aircraft striking wildlife, especially birds. This report provides aviation birdstrike and animal strike occurrence data for the period 1 January 2002 to 31 December 2009. It also describes the results of an ATSB survey of aerodromes concerning current wildlife control measures.

Reported birdstrikes have been generally increasing since 2002. In 2009, there were 1,340 birdstrikes reported to the ATSB. For high-capacity aircraft operations, reported birdstrikes have doubled from 2002 to 2009. However, taking into account an increase in aircraft movements, this increase is modest and is probably accounted for by a generally improving reporting culture within this time.

Birdstrikes have increased for the period of study in every Australian state and territory. Queensland, New South Wales, the Northern Territory and Western Australia have the highest birdstrike rates. The higher birdstrike numbers for Queensland and the Northern Territory may be related to bird populations within the tropics, while New South Wales has the highest number of major aerodrome aircraft movements in Australia.

Most birdstrikes occur within the confines of aerodromes (less than 5 km). Major and regional towered aerodromes had significantly higher rates of reported birdstrikes than General Aviation Airport Procedures (GAAP) aerodromes, and had considerably increasing rates from 2002 to 2009. GAAP aerodrome birdstrike rates do not appear to have changed.

Engine ingestion makes up 11 per cent of all birdstrike occurrences in high-capacity air transport for the 8- year period, and the highest number of damaging birdstrikes occurs in high-capacity air transport. Birdstrikes causing multiple parts damaged were not common throughout the period. General aviation had the highest proportion of damaging birdstrikes, with almost 24 per cent of birdstrikes causing damage. Aeroplane wings and helicopter rotor blades are the most commonly damaged aircraft components across all operational types, particularly in general aviation. There have been eight occurrences from the period of 2002-2009 that have resulted in serious aircraft damage, and four that have resulted in injury.

The most common types of birds struck by aircraft were lapwings/plovers, bats/flying foxes, galahs, and kites. Not surprisingly, larger birds were more likely to result in aircraft damage.

Animal strikes were relatively rare. High-capacity air transport had the highest average with 11.5 animal strikes per year, with general aviation having the second highest average with 9.3 animal strikes per year. The most common animals involved in strikes were hares/rabbits, kangaroos, wallabies, and foxes/dogs. Damaging strikes mostly involved kangaroos, wallabies and livestock.

Bird hazard control at aerodromes was found to be mostly related to the control of grass height (short or long) and growing specific plants or grass, and the daily or weekly use or auditory deterrents, especially car horns and shotguns.

Forty-four per cent of all accidents and over half of fatal accidents between 1999 and 2008 were attributed to private operations. These figures far surpassed the proportions for any other flying category, even though private operations contributed to less than 15 per cent of the hours flown in that decade.

This report aims to identify the factors contributing to fatal accidents in private operations and how these factors differed from non-fatal accidents. This was achieved through exploring common occurrence types (what happened), contributing factors (why the accident happened), contributing pilot errors, and aircraft and pilot characteristics.

Three occurrence types accounted for the majority of fatal accidents: collision with terrain (90%); loss of control (44%); and wirestrikes (12%). When all incidents and accidents are taken into account, the likelihood of being killed was about 36 per cent for a collision with terrain occurrence, 30 per cent for loss of control occurrences, and about 50 per cent for a wirestrike. For non-fatal accidents, there was greater variability in the common occurrence types - forced landings, hard landings, problems with the landing gear, and total power loss/ engine failure were also common.

Problems with pilots' assessing and planning were identified as contributing factors in about half of fatal accidents in private operations, and about a quarter involved problems with aircraft handling. Other contributing factors associated with fatal accidents to a smaller extent were visibility, turbulence, pilot motivation and attitude, spatial disorientation, and monitoring and checking. Non-fatal accidents were just as likely to involve aircraft handling problems, but had fewer contributing factors than fatal accidents.

Action errors and decision errors were both common to fatal accidents. Violations, while less frequently found, were mostly associated with fatal accidents.

In light of the contributing factors that were associated with fatal accidents in private operations, the report provides advice to pilots for improving the odds of a safe flight. Pilots are encouraged to make decisions before the flight, continually assess the flight conditions (particularly weather conditions), evaluate the effectiveness of their plans, set personal minimums, assess their fitness to fly, set passenger expectations by making safety the primary goal, and to seek local knowledge of the route and destination as part of their pre-flight planning. Also, becoming familiar with the aircraft's systems, controls and limitations may alleviate poor aircraft handling during non-normal flight conditions. Finally, pilots need to be vigilant about following rules and regulations that are in place - they are there to trap errors made before and during flight. Violating these regulations only removes these 'safety buffers'.

The ATSB receives around 15,000 notifications of aviation occurrences each year; 8,000 of which are accidents, serious incidents and incidents. It is from the information provided in these notifications that the ATSB makes a decision on whether or not to investigate. While further information is sought in some cases to assist in making those decisions, resource constraints dictate that a significant amount of professional judgement needs to be exercised.

There are times when more detailed information about the circumstances of the occurrence would have allowed the ATSB to make a more informed decision both about whether to investigate at all and, if so, what necessary resources were required (investigation level). In addition, further publicly available information on accidents and serious incidents would increase safety awareness in the industry and enable improved research activities and analysis of safety trends, leading to more targeted safety education.

To enable this, the Chief Commissioner has established a small team to manage and process these factual investigations, the Level 5 Investigation Team. The primary objective of the team is to undertake limited-scope fact-gathering investigations, which result in a short summary report. The summary report is a compilation of the information the ATSB has gathered, sourced from individuals or organisations involved in the occurrences, on the circumstances surrounding the occurrence and what safety action may have been taken or identified as a result of the occurrence.

The summary reports detailed herein were compiled from information provided to the ATSB by individuals or organisations involved in an accident or serious incident between the period 1 April 2010 and 30 June 2010.

The aviation industry has been slow to acknowledge the risks associated with ground operations. While most occurrences on airport aprons and taxiways do not have consequences in terms of loss of life, they are often associated with aircraft damage, delays to passengers and avoidable financial costs to industry. The focus of this report is to examine ground occurrences involving high-capacity aircraft operations.

This report examines occurrences involving ground operations and foreign object debris that occur at Australian airports which receive high-capacity aircraft. It uses occurrence and investigation data reported to the Australian Transport Safety Bureau to create a picture of ground occurrences. This picture begins when an aircraft is being prepared for takeoff and ends when passengers and crew have disembarked from the aircraft. It explores contributing factors associated with each type of occurrence, with the objective of providing some insight into what happened and why various events occurred. The key to preventing ground occurrences appears to revolve around ensuring effective communication between pilots, ground crews and air traffic services through a process of checks and balances.

This report tables rail safety occurrence data by state and territory between 1 January 2001 and 31 December 2009. Data is adjusted biannually to reflect new information that comes to light during the reporting period. There is a lag period of approximately 3 to 4 months between the end of the 6-monthly reporting period and publication of this data. The data is presented as counts, and normalised using kilometres travelled and number of track kilometres. Data presented in this report conforms to ON-S1: Occurrence Notification Standard 1 (2004) and OC-G1: Occurrence Classification Guideline 1 (2008). This report excludes tram and light rail or monorail operations.

Each year, 'responsible persons', as defined in the Transport Safety Investigation Regulations 2003, Part 2.5, provide the Australian Transport Safety Bureau (ATSB) with reports on aviation accidents and incidents, collectively termed occurrences. These reports are used by the ATSB to assist with the independent investigation of occurrences and for identifying safety trends.

This report provides aviation occurrence data for the period 1 January 1999 to 31 December 2009. The data contained herein is dynamic and subject to change pending the provision of new information to the ATSB. The data will be adjusted biannually to reflect new information received during the reporting
period.

For commercial air transport (high-capacity regular public transport (RPT), low-capacity RPT and charter), although the accident rate had climbed in 2007 and 2008, the number of accidents reduced from 29 (2008) to 11 in 2009. This accident trend was mostly driven by changes in the accident rate for charter operations. Similarly, the number of serious incidents for commercial air transport reduced from 45 (2007 and 2008) to 26 in 2009. There were no fatal air transport accidents in 2009. One significant accident in 2009 involved the tail scrape and runway excursion at take-off of a foreign-registered Airbus A340-500 in Melbourne on 20 March. Charter has an accident rate that is about five times that of low-capacity and high-capacity RPT. Most fatal accidents in commercial air transport are in charter operations, and it has a similar rate of fatal accidents to all general aviation.

For general aviation (aerial work, flying training, and private/business and (VH-registered) sport aviation), accidents and serious incidents have remained generally consistent since 2007. In 2009, there were 126 accidents, including 18 fatal accidents, and 95 serious incidents. Compared with flying training, aerial work has an accident rate per million hours that is two times higher, and private/business has an accident rate that is 2.5 times higher. In terms of fatal accidents per million hours, the fatality rate in aerial work is three times higher than flying training, and private/business is at least six times higher.

Summary

The ATSB receives around 15,000 notifications of aviation occurrences each year; 8,000 of which are accidents, serious incidents and incidents. It is from the information provided in these notifications that the ATSB makes a decision on whether or not to investigate. While further information is sought in some cases to assist in making those decisions, resource constraints dictate that a significant amount of professional judgement needs to be exercised.

There are times when more detailed information about the circumstances of the occurrence would have allowed the ATSB to make a more informed decision both about whether to investigate at all and, if so, what necessary resources were required (investigation level). In addition, further publicly available information on accidents and serious incidents would increase safety awareness in the industry and enable improved research activities and analysis of safety trends, leading to more targeted safety education.

To enable this, the Chief Commissioner has established a small team to manage and process these factual investigations, the Level 5 Investigation Team. The primary objective of the team is to undertake limited-scope fact-gathering investigations, which result in a short summary report. The summary report is a compilation of the information the ATSB has gathered, sourced from individuals or organisations involved in the occurrences, on the circumstances surrounding the occurrence and what safety action may have been taken or identified as a result of the occurrence.

The summary reports detailed herein were compiled from information provided to the ATSB by individuals or organisations involved in an accident or serious incident between the period 1 December 2009 and 30 March 2010.

Introduction

This publication is the first in a pilot education series by the Australian Transport Safety Bureau (ATSB) on avoidable accidents. In this report, we will focus on accidents involving unnecessary and unauthorised low flying; that is, flying lower than 1,000 ft (for a populous area) or 500 ft (for any other area) above ground level without approval from the Civil Aviation Safety Authority (CASA).

Between 1999 and 2008, there were 147 fatal accidents reported to the ATSB involving aerial work, flying training, private, business, sport and recreational flying in Australia. Of those fatal accidents, at least six were associated with unauthorised and unnecessary low flying. Those six accidents, along with a seventh non-fatal accident, presented here as case studies, were chosen by aviation safety investigators at the ATSB to highlight the inherent dangers of unauthorised low flying and to offer some lessons learnt from each case. It is hoped that these lessons learnt will help pilots make more accurate risk assessments and better decisions before electing to fly at low levels. 

Before you decide to conduct low-level flying, ask yourself whether there is a legitimate or operational reason for you to do so.

At low altitudes, there are many obstacles to avoid and there is a lower margin for error. Recognising the risks and hazards of low-level flying, CASA requires pilots to receive special training and endorsements before they can legally conduct low-level flying. In the accidents described in this booklet, most of the pilots had neither of these, and none had a legitimate reason to be flying below 500 ft. Some legitimate reasons for flying at low level include aerial stock mustering, crop spraying, and firefighting operations. For most private pilots, there is generally no reason to fly at low levels, except during take-off and landing, conducting a forced or precautionary landing, or to avoid adverse weather conditions.

What is sad and unfortunate about the accidents described in the following case studies is that they were all avoidable.

Conclusion

These case studies serve as salient reminders of the risks associated with low-level flight. Out of the seven accidents documented in this report, only one had survivors. Low-level flying is inherently unsafe for a number of reasons, so it should be avoided at all costs when there is no operational reason to do it (regardless of whether you have been trained and/or approved to do so). 

Flying at low level is unsafe because: 

• there are more obstacles to avoid, many of which are hard to see until it is too late (e.g. powerlines and birds)
• pilots have a higher workload because there are more hazards to negotiate in the environment
• there may be turbulence and windshear that pilots do not encounter at higher levels and
• there is very little time to recover control of the aircraft if something goes wrong.

From the accidents described here, it is apparent that the two major hazards of low flying are wirestrikes and pilots’ reduced opportunity to recover their aircraft from a stall or loss of control. 

It is important to keep in mind that powerlines also exist in remote areas where you least expect. For example, the pilots of the Stuart Highway accident probably did not expect powerlines in the remoteness of the Northern Territory, and the pilot of the Lake Eildon accident probably did not expect to encounter powerlines above the expanse of a large lake. 

The effects of wirestrikes at low level are obvious — significant damage to the aircraft, usually leading to a loss of control and, because of the lower margin for recovery, subsequent impact with the ground or water. Pilots must keep in mind that not only do powerlines exist at low levels and in remote areas, they are also not easy to identify. Even against a clear blue sky, wires are difficult to spot for a number of reasons. Wires can oxidise to a blue/grey tinge and may blend into the background (ATSB, 2006), or the wire may be obscured by terrain. Single wires are difficult to detect from the air and can be encountered in the most unexpected places in rural areas. Even if a pilot has spotted a powerline, his or her ability to judge its distance from the aircraft can be distorted by optical illusions or a lack of nearby visual reference points. 

Pre-flight assessment and planning is an important part of any flight. Make sure you have maps of your intended flight path with you when you fly, and study them before you get into your aircraft to identify any terrain, wire, or other obstacles that you need to avoid should operational circumstances necessitate flight at low level. If you have been trained and are qualified for low flying, and low flying is necessary, ensure that you conduct an aerial survey of the area from an appropriate height before you conduct any low flying.

Low-level flying also presents fewer opportunities to recover from a loss of control compared to flight at higher altitudes. It takes time to react and to regain control of an aircraft, and the closer to the ground you are, the less time and distance you have. Flying at low altitudes is not only risky when things are going right; it becomes downright perilous when things are going wrong. 

Before you decide to conduct low-level flying, ask yourself whether there is a legitimate or operational reason for you to do so.

On the early evening of 31 January 2001 at Melbourne International Airport, Boeing 777-300 A6-EMM aborted its take-off run at low speed as a result of a failure within the left (No.1) engine. Although the failure was associated with a large compressor surge within the engine, no subsequent fire developed and the aircraft was able to safely return to the terminal building on its remaining serviceable engine.

Failure of the RB211 Trent 892 engine as fitted to the aircraft was a result of the release of a single blade from the low-pressure compressor (fan) rotor disk. The blade release caused extensive damage to the remainder of the fan and the intake shroud, however the event was fully contained. The only escape of debris from the engine was small, low energy fragments, causing minor damage to the fuselage and the opposite engine.

Field and laboratory examination of the released blade found that progressive fatigue cracking had resulted in the loss of two major sections from the blade dovetail root. The remaining material was subsequently unable to carry the centrifugal loads associated with the accelerating engine and failed in ductile shear, allowing the release of the blade from the rotor slot. No defects or other anomalous material or manufacturing features were found to have contributed to the crack development.

The blades installed within the Trent 892-17 engine were an approved variant of the original design, incorporating an undercut radius between the dovetail faces and the blade body. The modification was developed in order to avoid 'edge of bedding' stresses that had been implicated in blade cracking on development engines. Cracking of the released blade had initiated within this undercut radius on both sides of the shear key slot; locations that had been identified by finite element techniques as areas of high localised stress. Extensive galling of the seating surfaces was also found on all blades, indicating the long-term inadequacy of the dry film lubricant applied to the blade dovetail faces. The galling and micro-welding damage can readily interfere with the distribution of loads across the seating surfaces, leading to elevated stresses within the blade root.

Blade failure was thus attributed to an interaction of the following -

• Design - provided for areas of localised high tensile stresses arising from operating loads.
• Operating Stresses - act on the blade to produce cracking in areas highlighted by the design. In the absence of defects predisposing the blade to failure, the development of cracking implies elevated operating stress levels.
• Blade - Disk Connection Problems - galling of the dovetail surfaces indicates the potential for uneven load distribution through the connection, leading to increased stresses within the blade root and thus a greater disposition to fatigue cracking.

Although several studies have reported the common threats and errors identified in line operations safety audits (LOSAs) of high-capacity regular public transport (RPT) operations (Klinect, Wilhelm & Helmreich, 1999; Veilette, 2005; Thomas, 2004), there is little information on the types of threats and errors faced by pilots in other parts of the aviation industry.

This report catalogues the most common threats to operations, and errors made by pilots, in aerial work and low-capacity air transport operations, as perceived by flight instructors, check-and-training pilots, chief pilots and line pilots. The aim of this report is to provide a snapshot of these perceived threats and errors, along with ratings of safety deficiencies, and to offer some suggestions in how to deal with threats and errors.