Introduction

This ATSB booklet aims to increase awareness among flying instructors and pilots of the issues relating to partial power loss after take-off in single-engine aircraft. Accident investigations have shown that a significant number of occurrences result in fatalities or serious injury due to the aircraft stalling and subsequent loss of control resulting in a collision with the ground or water.

Historically, the simulated total loss of power and subsequent practice forced landing has been the core of a pilot’s emergency training. The data, however, shows that during and after take-off, a partial power loss is three times more likely in today’s light single-engine aircraft than a complete engine failure. Furthermore, there have been nine fatal accidents from 2000 to 2010 as a result of a response to a partial power loss compared with no fatal accidents where the engine failed completely. 

While one reason for the disparity in these statistics could be the more challenging nature of partial power loss, due to the choices confronting a pilot and the decisions that have to be made immediately, it does not fully explain the different outcomes. Another possible factor is training. Total engine failure after take-off is part of the Day VFR syllabus and is taught and practiced throughout a pilot’s initial training. However, partial power loss after take-off is not a specific syllabus item, and probably does not receive the same emphasis during training.

While acknowledging the difficulty of attempting to train pilots for a partial power loss event which has an almost infinite variability of residual power and reliability, analysis of the occurrences supports the need to raise greater awareness of the hazards associated with partial power loss and to better train pilots for this eventuality. 

Partial engine power loss is more complex and more frequent than a complete engine power loss.

Key messages

Most fatal and serious injury accidents resulting from partial power loss after take-off are avoidable. This booklet will show that you can prevent or significantly minimise the risk of bodily harm following a partial or complete engine power loss after take-off by using the strategies below: 

• pre-flight decision making and planning for emergencies and abnormal situations for the particular aerodrome
• conducting a thorough pre-flight and engine ground run to reduce the risk of a partial power loss occurring
• taking positive action and maintaining aircraft control either when turning back to the aerodrome or conducting a forced landing until on the ground, while being aware of flare energy and aircraft stall speeds.

Summary

Pre-flight checks prevent partial power loss

ATSB occurrence statistics indicate that many partial power losses could have been prevented by thorough pre-flight checks. Some conditions reported as causing partial power loss after take-off are fuel starvation, spark plug fouling, carburettor icing and pre-ignition conditions. In many cases, these conditions may have been identified throughout the pre-take-off and on-take-off check phases of the flight sequence.

Pre-flight planning and pre-take-off briefings

Even if a partial power loss does occur after take-off, considering actions to take following a partial power loss after take-off during the process of planning and the pre-flight safety brief gives pilots a much better chance of maintaining control of the aircraft, and helps the pilot respond immediately and stay ahead of the aircraft. Considerations include planning for rejecting a take-off, landing immediately within the aerodrome, landing beyond the aerodrome, and conducting a turnback towards the aerodrome. 

Stay in control

If nothing else, maintain glide speed and plan a maximum bank angle against your personal minimums, which you will not exceed if a turnback is an option. Be prepared to re-assess the situation throughout any manoeuvre.

Wirestrikes pose an on-going problem to aerial agricultural operations. There are 180 wirestrike accidents in the Australian Transport Safety Bureau (ATSB) database for the period between 2001 and 2010. Of these, 100 involved agricultural flying. Research by the ATSB has shown that 63 per cent of pilots were aware of the position of the wire before they struck it.

This publication describes recent aerial agricultural wirestrike accidents. In all these cases, the aircraft struck a powerline that was known to the pilot. In many of these accidents, the pilot was not completely focused on the immediate task of flying due to a change in plans.

This publication also explains a number of strategies developed by the Aerial Agriculture Association of Australia (AAAA) and the ATSB to help agricultural pilots manage the on-going risk of wirestrikes during spraying operations. These include:

• ensure you are physically and mentally fit to fly
• set client expectations so that they are clear that safety comes first
• conduct a thorough briefing and study a detailed map of the area before the flight
• conduct an aerial reconnaissance before spraying and conduct an extra aerial reconnaissance before the clean-up run
• reassess the risks when plans change
• avoid unnecessary distractions and refocus when distracted
• be aware of vigilance limitations
• don’t rely on your ability to react in time to avoid a wire
• actively look for and remind yourself of wires
• be aware of and manage pressures
• have a systematic approach to safely managing wires.

A number of changes have been made to this document since it was first published in May 2011. The number of occurrences reported have remained the same, and only the rates of occurrences per departure or hours flown have changed. See page vi of AR-2011-020 for further details.

In 2010, uncontained engine failures occurred on two high-capacity aircraft (a Boeing 747 and an Airbus A380); two air transport aircraft almost collided in non-controlled airspace, coming within 40 metres of each other; and a cockpit window blew out of a Metro aircraft at about 20,000 feet, resulting in a rapid cabin decompression. These are some of the occurrences described in a new report on occurrence data for the period 2001 to 2010. The Australian Transport Safety Bureau (ATSB) has tabled a list of frequently occurring events and presents them in this report along with trends over time.

During 2010, the top five most frequently occurring events for air transport relating to accidents and serious incidents were aircraft separation, aircraft control, powerplant and propulsions systems, miscellaneous events and terrain collisions, runway events and ground operations. For air transport incidents they were wildlife strikes, failure to comply, mechanical systems, miscellaneous and airframe events. For general aviation aircraft involved in accidents and serious incidents, the top five most frequently occurring events were terrain collisions, aircraft control, powerplant and propulsion, aircraft separation and runway events. Where general aviation aircraft were involved in an incident, the top five most frequently occurring events were airspace incursion, failure to comply, wildlife strikes, runway events and aircraft separation.

General aviation operations continue to have a fatal accident rate per million departures that is about 4.3 times higher than for air transport. The general aviation accident rate per million departures is about three times higher than air transport. No fatal accidents were recorded in high-capacity air transport between 2001 and 2010. During 2010, there was one fatal accident in low-capacity air transport, and charter operations recorded no fatal accidents. Between 2001 and 2010, most fatal accidents in air transport were in charter operations. Charter aeroplanes and helicopters have a similar accident and fatal accident rate. In air transport, charter operations offer the best potential target for safety improvement.

In general aviation, there were 147 fatal accidents and 236 people killed between 2001 and 2010. The general aviation accident and fatality rate is not evenly dispersed across all sub-groups or types of aircraft. Of all general aviation sub-groups, private/business flying has the highest fatal accident rate and the greatest number of fatalities (135 people between 2001 and 2010). Agriculture has the highest accident rate and second highest fatal accident rate. This is followed by mustering, survey and photography, and flying training. In aerial work, helicopters have a higher accident and fatal accident rate than aeroplanes. In contrast to this, flying training and private operations helicopters have a higher accident rate than aeroplanes, but overall, are associated with a smaller number of total fatalities.

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 Short 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. In addition, the ATSB may include a Safety Message that is directed to the broader aviation community.

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 January 2011 and 31 March 2011.

In the 2009-2010 financial year, the Australian Transport Safety Bureau (ATSB) completed 37 aviation, 10 marine, and 11 rail investigations where safety factors were identified using the ATSB analysis framework. From these investigations, 124 safety issues (factors that have a potential to adversely affect the safety of future operations) were identified and 141 safety actions were undertaken to address these safety issues. This report documents and analyses these safety issues and safety actions and explores the risk levels assigned to provide an understanding of where the greatest risks to each transport mode appear to lie. The results will be useful for government decision makers, regulators and the aviation, rail and marine industries to understand if and where attention to risk needs to be applied.

Inadequate procedures or the lack of procedures were a common safety issue found by ATSB investigations for all transport modes. In rail investigations, problems with safety management process practices were slightly more common than problems with procedures. When safety issues are assessed by the level of risk posed to transport safety, the lack of procedures or inadequate procedures were found to carry the most significant safety risk for all three modes.

Deck and flight operations were the functional areas that were associated with the most safety issues in marine and aviation investigations respectively. These were also the functional areas (along with navigation - pilotage for marine) that were linked to the majority of the safety issues carrying significant risk. For rail, vehicle maintenance and network operations were associated with the most safety issues of significant risk.

Proactive industry safety action was the most common way safety issues identified in investigations were addressed across the aviation and marine modes, while proactive industry safety actions made up only half of the safety actions taken by the rail mode.

Amending or adding procedures was a common proactive industry safety action for all modes. This was particularly the case for safety issues that carried significant safety risk. For marine, the proactive industry safety actions taken spread across various categories such as procedures, organisational supervision, documentation, education, and training. In addition, proactive changes or additions to documentation were the second most common proactive industry safety action for the aviation industry.

Everyday errors such as incorrectly transcribing or inadvertently dialling a wrong telephone number normally have minimal consequences. For high-capacity aircraft operation, the consequence of such errors can be significant. There have been numerous take-off accidents worldwide that were the result of a simple data calculation or entry error by the flight crew. This report documents 20 international and 11 Australian accidents and incidents (occurrences) identified between 1 January 1989 and 30 June 2009 where the calculation and entry of erroneous take-off performance parameters, such as aircraft weights and 'V speeds' were involved. Importantly, it provides an analysis of the safety factors that contributed to the international occurrences and suggests ways to prevent and detect such errors.

A review of the international and Australian occurrences showed that these types of errors have many different origins; with crew actions involving the wrong figure being used, data entered incorrectly, data not being updated, and data being excluded. Furthermore, a range of systems and devices have been involved in these errors, including performance documentation, laptop computers, the flight management computer, and the aircraft communications addressing and reporting systems. The consequences of these errors also ranged from a noticeable reduction in the aircraft's performance during the take-off, to the aircraft being destroyed and loss of life.

The most common contributing safety factor identified related to crew actions (39 per cent), including monitoring and checking, assessing and planning, and the use of aircraft equipment. This was followed by absent or inadequate risk controls (31 per cent), mostly centred on poor procedures, non-optimally designed aircraft automation systems, inappropriately designed or unavailable reference materials, and inadequate crew management practices and training. Common local conditions (27 per cent) involved inadequate task experience or recency, time pressures, distractions and incorrect task information.

Different airlines use, and different aircraft types require, different methods for calculating and entering take-off performance parameters, which means there is no single solution to ensure that such errors are prevented or captured. This report also discusses several error capture systems that airlines and aircraft manufacturers can explore in an attempt to minimise the opportunities of take-off performance parameter errors from occurring or maximise the chance that any errors that do occur are detected and/or do not lead to negative consequences.

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. In addition, the ATSB may include an ATSB Comment that is a safety message directed to the broader aviation community.

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 October 2010 and 31 December 2010.

This report tables rail safety occurrence data by state and territory between 1 January 2001 and 31 December 2010. 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, light rail and monorail operations.

This report documents the number and types of safety occurrences involving loading of high-capacity aircraft across a 7-year period to raise awareness within the aviation industry of the associated issues. Incorrect loading of containers, pallets or bags into aircraft can result in them being outside of weight or centre of gravity operating limits, and this may influence aircraft controllability. Most high-capacity aircraft loading occurrences are relatively minor, with cargo locks not being raised being the most common. More serious occurrences have involved shifting cargo and unlisted cargo being loaded onto aircraft. Aircraft performance has been affected in a small number of cases, and the result has been rejected take-off, extra stabiliser trim, or aircraft control difficulties.

The Human Factors Analysis and Classification System (HFACS) is a hierarchical taxonomy that describes the human factors that contribute to an aviation accident or incident that is based on a chain of- events theory of accident causation and was derived from Reason's (1990) accident model.

The objectives of this exploratory study were to identify relationships between the factors of the HFACS taxonomy and to assess the usefulness of HFACS as a predictive tool. The associations found in this study may assist investigators in looking for associated factors when contributing factors are found. Also, when using the HFACS taxonomy to identify areas for intervention, the relationships found may also guide intervention in associated areas for a holistic, systems approach to improvement.

This exploratory study found a number of strong positive relationships between factors at different levels of the model. However, based on the amount of variation explained by the logistical regression statistical models, it appears that HFACS is a more effective predictive framework when used to predict unsafe acts than when used to predict higher levels within the taxonomy.

The Australian Transport Safety Bureau (ATSB) formalised the concept of outside influences and added five factors within this grouping to the HFACS model in this study. The outside influences factors proved to be important additions to the HFACS model as they were associated with factors at all levels of the HFACS taxonomy.

The results have also shown that it is not always the case that higher-level factors predict only the lower-level factors directly below them. For example, inadequate supervision predicted precondition for unsafe acts, such as adverse mental states and crew resource management issues, as well as skill-based errors (two levels down).