Air Traffic Management accident risk. Part 2: Repairing the deficiencies of ESARR4

This is a critique of ESARR4 and its main supporting documents. ESARR4 is the Eurocontrol Safety Regulatory Requirement Number 4 [Eurocontrol safety regulatory requirement ESARR4, Edition 1.0., Eurocontrol, Safety Regulation Commission, Brussels, 2001]: ‘Risk assessment and mitigation in ATM’, ATM standing for Air Traffic Management. It is demonstrated that ESARR4 and its supporting documents are defective. There is a lack of clarity about responsibilities for ATM safety. The claims ESARR4 etc. make for its proposed methodologies are overstated—not supported by sound evidence from real world hazard analysis. Serious negative effects from this defective document include mis-allocation of scarce safety resources and the diversion of attention away from real safety improvements—wasteful of regulators’ and managers’ time. Suggestions are made for repairing these deficiencies. The most important underlying change would be a refocusing on practical safety assessment based on methods that have already demonstrated their merits.     

The limits to risk aversion: Part 1. The point of indiscriminate decision

The paper uses utility theory to investigate how much should be spent to avert all costs from an industrial accident apart from direct human harm. These “environmental costs” will include those of evacuation, clean-up and business disruption. Assuming the organisation responsible will need to pay such costs, the difference between its expected utility with and without an environmental protection system constitutes a rational decision variable for whether or not the scheme should be installed. The value of utility is dependent on the coefficient of relative risk aversion, “risk-aversion” for short. A model of an organisation's decision-making process has been developed using the ABCD model, linking the organisation's assets, A, the cost of the protection scheme, B, the cost of consequences, C, and the expected utility difference with and without the scheme, D. Increasing the organisation's risk-aversion parameter will tend to make it less reluctant to invest in a protection system, but can bring about such investment only when the scheme is relatively close to financial break-even. For such borderline schemes, the amount the organisation is prepared to spend on the protection system will rise as the risk-aversion increases. The ratio of this sum to the break-even cost is named the “Limiting Risk Multiplier”, the maximum value of which is governed by the maximum feasible value of risk-aversion. However, the mathematical model shows that increasing the risk-aversion will reduce the clarity of decision making generally. Although the reluctance to invest in a protection scheme may change sign and turn into a positive desire to invest as the risk-aversion increases, the absolute value of this parameter is a continuously decreasing function of risk-aversion, tending asymptotically to zero. As a result, discrimination will gradually diminish, being lost altogether at the “point of indiscriminate decision”. Here the decision maker will be able to distinguish neither advantage in installing the scheme nor disadvantage in installing its inverse. There is a close correspondence between this mathematically predicted state and that of panic, where an individual has become so fearful that his actions become random. The point of indiscriminate decision provides a natural upper bound for the value of risk-aversion. This bounds the Limiting Risk Multiplier in turn, and so sets an objective upper limit on the amount that it is rational to spend on an environmental protection system.     

The limits to risk aversion: Part 2: The permission point and worked examples

Part 2 extends the analysis to show that it is possible to find the “permission point”, the value of (the coefficient of relative) risk-aversion, at which decisions to sanction environmental protection are most likely to be made. The mathematical model describes the process by which the decision maker varies his risk-aversion over a range of feasible values to find the risk-aversion that will give him the greatest desire to invest in the protection system under consideration. If he can find such a risk-aversion before losing discrimination (because the system is too expensive, given its performance), he will adopt it as his “permission point” and decide in favour of the expenditure. The permission point is, of course, bounded above by the point of indiscriminate decision. A maximum Risk Multiplier calculated at the point of indiscriminate decision may be applied to the protection expenditure at monetary break-even to give the maximum, rational outlay on protection. Moreover, it is possible to model how the average UK adult should take decisions on protection to maximise his utility. Different situations will call for different values of risk-aversion, which may explain why economists have come up with differing estimates of this parameter in the past. However, a central, average risk-aversion may be calculated for the average UK adult as 0.85, which is within 4% of the value, 0.82, found from the newly reported method based on a trade-off between income and future free time, and is consistent with several recent economic estimates. Worked examples assess how much an organisation should spend on a protection scheme to prevent accidents with very large environmental consequences.     

空管安全风险管理信息系统分析与设计

针对空中交通服务管理系统(简称为"空管",下同)中存在的安全管理不规范、安全信息不畅通和信息化程度低等安全管理问题,根据空管安全风险管理信息系统(SRMIS)的工作原理,提出SRMIS的业务流程和组织结构,设计了SRMIS的总体结构、风险管控和指标预警等主要功能,研究实现过程中的指标评价、部门评价和模糊综合评价等信息评价方法以及指标预警、因素预警和综合预警等预警预控方法和关键技术。该系统能进行持续的风险识别和综合预警,定期自检、自查、自审,不断改进安全管理工作,并在武汉空管中心实证有较好的应用效果,为空管中心的安全风险管理提供了信息化管理的工具和途径。     

The major accident risk (MAR) process - developing the profile of major accident risk for a large multi national oil company

The paper describes a programme to develop the profile of major accident risk across a large multi national oil company. It describes the concepts, tools and processes for constructing the risk profile and some of the key learnings from the exercise.     

The development of a more risk-sensitive and flexible airport safety area strategy: Part I. The development of an improved accident frequency model

This two-part paper presents the development of an improved airport risk assessment methodology aimed at assessing risks related to aircraft accidents at and in the vicinity of airports and managing airport safety areas (ASAs) as a risk mitigation measure. The improved methodology is more quantitative, risk-sensitive, flexible and transparent than standard risk assessment approaches. As such, it contributes to the implementation of Safety Management Systems at airports, as stipulated by the International Civil Aviation Organisation.The first part of the paper presents the methodological advances made in the development of accident frequency models; namely the building of a single comprehensive database of all relevant accident types, the collection and use of normal operations data in quantifying the criticality of a series of risk factors, and modelling accident frequency using multivariate logistic regression. The resulting models have better goodness-of-fit, sensitivity and specificity than standard risk assessment methodologies.     

Steady-state critical two-phase flashing flow with possible multiple choking phenomenon: Part 1: Physical modelling and numerical procedure

In this paper, the modelling of pure fluid steady-state adiabatic flashing flow through a pipe involving an abrupt enlargement is presented. The thermal non-equilibrium two-phase flow model DEM has been adjusted for subcooled inlet conditions close to saturation and/or for inlet two-phase mixture state. The multichoking flow phenomenon occurs when two basic criteria are simultaneously fulfilled. A general procedure taking into account this possible occurrence is developed on the basis of two iterative algorithms. The first algorithm is applied to the mass flow rate upstream from the enlargement and the second algorithm is based on the length of the pipe downstream from the enlargement. The proposed methodology involves the improved physical one-dimensional two-phase flow model DEM and the global non-equilibrium model through the abrupt enlargement.     

Measuring safety culture in a research and development centre: A comparison of two methods in the Air Traffic Management domain

This paper describes two safety surveys carried out in an Air Traffic Management Research and Development centre (EUROCONTROL Experimental Centre). The paper discusses the differences and similarities between the two tools with regard to their development, the method of conducting the surveys, the results and their implications. It has been estimated that about 50%¹ to 60%² of accidents and incidents appear to have their roots in the design and development process, and since this is the core business of the EEC, it was deemed necessary to investigate the maturity of safety at the EEC. The challenge for the EUROCONTROL Experimental Centre (EEC) was to develop a tool that is relevant to a research and development environment with the objectives of (i) identifying areas of weakness in the safety culture of the organization (ii) helping in developing a Safety Management System. The first objective was addressed by developing a Safety Culture Survey (SCS) tool and surveying the EEC (March, 2003). The second objective was addressed by customizing an existing (SMS) survey tool (RD) for the R&D environment. The SCS is based on traditional measures adapted to ATM and then to R&D, and the River Diagram (RD) is more of a safety management survey, adapted from other industries and already applied to HQ (EUROCONTROL Head Quarters) to examine their commitment to safety. Nevertheless, the two surveys have been compared to see where they agree and where they ‘dissociate’. Overall, the SCS has a broader focus on “softer issues”, i.e. more complex issues of ‘trust in management’. Diagnostically, the River Diagram survey helps the practitioner develop SMS implementation plans more readily than the Safety Culture survey.     

Traffic accident reconstruction and an approach for prediction of fault rates using artificial neural networks: A case study in Turkey

Objective: Currently, in Turkey, fault rates in traffic accidents are determined according to the initiative of accident experts (no speed analyses of vehicles just considering accident type) and there are no specific quantitative instructions on fault rates related to procession of accidents which just represents the type of collision (side impact, head to head, rear end, etc.) in No. 2918 Turkish Highway Traffic Act (THTA 1983). The aim of this study is to introduce a scientific and systematic approach for determination of fault rates in most frequent property damage–only (PDO) traffic accidents in Turkey.

Methods: In this study, data (police reports, skid marks, deformation, crush depth, etc.) collected from the most frequent and controversial accident types (4 sample vehicle–vehicle scenarios) that consist of PDO were inserted into a reconstruction software called vCrash. Sample real-world scenarios were simulated on the software to generate different vehicle deformations that also correspond to energy-equivalent speed data just before the crash. These values were used to train a multilayer feedforward artificial neural network (MFANN), function fitting neural network (FITNET, a specialized version of MFANN), and generalized regression neural network (GRNN) models within 10-fold cross-validation to predict fault rates without using software. The performance of the artificial neural network (ANN) prediction models was evaluated using mean square error (MSE) and multiple correlation coefficient (R).

Results: It was shown that the MFANN model performed better for predicting fault rates (i.e., lower MSE and higher R) than FITNET and GRNN models for accident scenarios 1, 2, and 3, whereas FITNET performed the best for scenario 4. The FITNET model showed the second best results for prediction for the first 3 scenarios. Because there is no training phase in GRNN, the GRNN model produced results much faster than MFANN and FITNET models. However, the GRNN model had the worst prediction results. The R values for prediction of fault rates were close to 1 for all folds and scenarios.

Conclusions: This study focuses on exhibiting new aspects and scientific approaches for determining fault rates of involvement in most frequent PDO accidents occurring in Turkey by discussing some deficiencies in THTA and without regard to initiative and/or experience of experts. This study yields judicious decisions to be made especially on forensic investigations and events involving insurance companies. Referring to this approach, injury/fatal and/or pedestrian-related accidents may be analyzed as future work by developing new scientific models.     

矿山重大危险源评价及瓦斯爆炸事故伤害模型建立的若干研究

基于危险源评价的基本原理 ,结合系统论的观点与矿山重大危险源的实际 ,确立了矿山重大危险源伤害模型的合理假设和简化 ,并在此基础上 ,首次提出了从危险源系统事故的伤害模型来研究矿山矿井瓦斯爆炸事故的严重度方法 ;并结合矿井瓦斯爆炸事故的实际 ,建立了瓦斯爆炸事故冲击波的伤害模型。使得目前人们通常认为无法对矿井瓦斯爆炸事故严重度研究进行建模成为可能 ,这无疑是对矿山重大危险源评价工作和瓦斯爆炸事故研究的一次重大创新和完善     

The development of a more risk-sensitive and flexible airport safety area strategy: Part II. Accident location analysis and airport risk assessment case studies

This two-part paper presents the development of an improved airport risk assessment methodology aimed at assessing risks related to aircraft accidents at and in the vicinity of airports and managing Airport Safety Areas (ASAs) as a risk mitigation measure. The improved methodology is more quantitative, risk-sensitive, flexible and transparent than standard risk assessment approaches. As such, it contributes to the implementation of Safety Management Systems at airports, as stipulated by the International Civil Aviation Organisation.The second part of the paper presents the analysis of accident locations, including the plotting of Complementary Cumulative Probability Distributions for the relevant accident types. These were then used in conjunction with the improved accident frequency models to produce Complementary Cumulative Frequency Distributions that could be used to assess risks related to specific runways and determine Airport Safety Area (ASA) dimensions necessary to meet a quantitative target level of safety. The approach not only takes into account risk factors previously ignored by standard risk assessments but also considers the operational and traffic characteristics of the runway concerned. The use of the improved risk assessment technique and risk management strategy using ASAs was also demonstrated in two case studies based on New York LaGuardia Airport and Boca Raton Airport in Florida.     

The development and evaluation of accident prevention routines: A case study

Information resulting from the occurrence of accidents and near-accidents is the basis for most accident prevention efforts. However, such information may not normally be incorporated into local safety activities. A group to assist supervisors in their investigations of accidents and a procedure to prompt the reporting of near-accidents by employees were tested at one company as means of improving local safety activities. The accident investigation group was in operation in all departments and was associated with improved accident reporting and prevention activities as well as a reduction in accident severity. The near-accident reporting procedure was tested in one department and led to improved knowledge about risks, although no reductions in accident frequency and severity were shown. On the basis of these results, the company safety committee decided at the end of the first year to extend the mandate of the investigation group but not to continue with near-accident reporting. Follow-ups after 2 and 3 years indicated that improvements in prevention activities had been maintained and that accident severity had been further reduced.     

交通安全管理应对城乡交通一体化建设对策分析——以阜阳城区交通为例

以阜阳为例,分析城乡交通一体化建设给阜阳城区交通安全管理带来的挑战,通过对阜阳市城区路网结构、交通参与者的交通安全意识和交通安全管理压力3个方面的实地调查,得出传统交通管理模式已不能满足城乡交通一体化建设带来的新交通形势需要的结论。在借鉴国外发达国家交通安全管理对策的基础上,提出应对城乡交通一体化建设的交通安全管理策略:挖掘路网潜能治理混合交通策略、城乡交通一体化建设针对性管理策略和发展智能交通系统实现交通安全管理升级策略,使交通安全管理能够有效应对城乡一体化建设带来的各种挑战。     

道路交通事故成为第一杀手

随着经济发展,汽车、船舶等交通工具增加,人们对交通工具依赖程度越来越高。由于我国汽车增长速度超过了道路发展速度,以及私营业主介入汽车运输经营等,我国道路交通事故已成为安全生产的第一杀手。记者从1月16日召开的全国安全生产工作会议上了解到,2002年山东省因道路交通     

为了生命的呼唤——王家岭矿3·28透水事故救援全纪录

灾变——153个生命在死亡边缘2010年3月28日清晨8点,吃过早饭,孟小兵和红旗队掘进班的其他5名工友领了矿灯和任务条就下了井,来到回风大巷工作面。像往常一样,他熟练地操起凿岩机开始向巷道深处掘进。