Selasa, 22 Maret 2011

Concepts Used In Risk Assessments, case of ARFF operations

As Low As Reasonably Practical (ALARP)

There are a number of concepts that can be used in the conduct of risk assessment. The HSE for instance uses the concept of ‘As Low As Reasonably Practical’ (ALARP) in determining the risk reduction requirements of duty holders in providing a safe environment for patrons. However, as the HSE points out, there is little guidance from the courts as to what reducing risks to as low as practically possible means. In the case of Edwards versus The National Coal Board for example, the Court of Appeal held that “…in every case, it is the risk that has to be weighed against the measures necessary to eliminate risk. The greater the risk, no doubt, the less will be the weight to be given to the factor of cost.” (HSE, 2001).
The term used in the ALARP principle is “Reasonably Practical” and not “Physically Possible”. Accordingly, some computation needs to be made in determining the risk involved in a particular situation and the level of sacrifice (whether in terms of time, money or inconvenience) that is required to avert that risk. This computation will give an indication as to whether the risk is insignificant in relation to the sacrifice, which in turn will give an indication as to whether the onus is on the duty holder to reduce that risk.
The above process is by no means an easy task, neither is it an exact science as it calls for much subjectivity. Nevertheless, there is a need for systematic approaches to comparing risks with sacrifices. The more systematic the approach applied, the more likely it is to be rigorous and transparent to regulators and other stakeholders. Given the nature of commercial air transport as a high profile industry, there is no doubt that the approach to assessing risk and implementing mitigating measures ought to be systematic, rigorous and transparent. In the case of ARFF operations, the risks involved arise mainly from extenuating circumstances over which the RFF operators have little or no control but are called on to mitigate. These extenuating circumstances therefore form a major component of the risk assessment that should be conducted for such operations and this makes the process even more challenging.
Naturally, there will be some costs associated with risk reduction measures employed by an organization. Although these costs will be in terms of time, inconvenience and/or money, for many operators and in many situations, monetary constraints will be the key factor that has to be taken into consideration. However, the HSE holds the position that the duty holder’s ‘ability to afford a control measure or financial viability of a particular project is not a legitimate factor in the assessment of its costs’. To this end, the HSE does not take into account the size of the duty holder nor their financial position when determining whether the ALARP principle was applied.
On the other hand, the HSE also holds the position that the benefits gained as a result of implementing a particular mitigating measure should outweigh the costs incurred. Whilst this may be a reasonable position to hold, often is the case that benefits or the potential benefits to be derived from a particular risk reduction measure vary according to the perceptions of the parties involved. For instance, an airport that is ‘in the red’ annually, may not see the need for increasing their ARFF equipment or investing in training of personnel, particularly if in the view of that airport authority, there has been few (and only minor) accidents or incidents in the past for the emergency personnel to attend. Conversely, pilots flying to that particular airport may be comforted in knowing that the ARFF team is adequately equipped to deal with an emergency should it arise.

The Precautionary Principle

Another principle used in conducting risk assessments is the precautionary principle. In the HSE document entitled ‘Reducing Risks Protecting People: The HSE Decision Making Process’, the United Nations Conference on the Environment and Development (UNCED) is reported to have indicated that the precautionary principle presumes the following:
‘where there are threats of serious or irreversible environmental damage, lack of full scientific certainty shall not be used as a reason for postponing cost effective measures to prevent degradation.’
This principle is therefore used in cases where the hazard is subject to a high degree of uncertainty. Initially, it was applied to risks assessments conducted in situations where environmental protection was necessary, particularly if global issues such as climate change and ozone depletion were involved. The principle is now more widely used across a variety of sectors and may be employed under the following conditions:
• There is empirical evidence or plausible causal hypotheses to suggest that serious harm may occur, even if the probability that the harm occurring is extremely low; and
• The scientific information gathered suggests that the degree of uncertainty is so high that it is impossible to evaluate the consequences with enough confidence to proceed to the next stage.
However, it should be noted that the degree of uncertainty may be reduced by creating plausible scenarios regarding the nature of a hazard and how it is likely to come to reality. In this way, credible assumptions can be made about the consequences of the risks and their likelihood.
In the absence of a more suitable principle for dealing with decisions to implement safety measures, this principle will be used as the basis for this thesis, along with the ALARP principle. It is felt that this principle is appropriate for this study given that, although the probability of accidents or serious incidents in the countries under review may be relatively low, the evidence suggests that the types of aircraft accidents that are likely to occur can result in serious harm and multiple fatalities.

Quantitative Risk Assessment

Another approach commonly used in risk analysis is the quantitative risk assessment (QRA). The QRA is used to show the relationship between different subsystems and their reliance on the overall system. However, this method can lead to highly inaccurate or misconstrued results, particularly in cases where historical data on accidents or incidents is used. The following are some of the discrepancies that are likely to give rise to the wrong impression about a particular situation:
• The sample that was selected was too small, too narrow or too wide;
• The time period selected was too short in which case representative accidents may have been omitted; or
• The time period selected was too long in which case a number of irrelevant accidents may have been included.
Any of the afore-mentioned discrepancies will affect the robustness of the results of the QRA and consequently, may lead to decisions that do not adequately address the level of safety required. To this end, any use of the QRA method should also include operational and where appropriate, engineering analyses in making an overall decision.

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