Keywords

1 Introduction

Modern safety management theory emphasizes the safety management should focus on active management rather than passive management. At present, the safety level of airport in China is always evaluated through high consequences indicators like incident rate. This “ex-post” evaluation method makes the regulator and airport focus on the occurrence of incidents rather than the risk management capability and prevention capacity. For the airport, no accident does not mean the risk level is low. Therefore, in addition to the accidents or incidents, the airport also should pay close attention to the state of the operational process. If we can take the active management, monitor the safety risk factors or the state of operational state and alert staff to take measures before accidents or incidents, airport operational safety can be promoted. This is the highest goal pursued by airport safety management work.

This research designs airport operational safety risk monitoring indicators based on the risk management theory and safety performance management theory. And then builds the operational risk warning model. This model can monitor the airport safety risk and help the airport detect the abnormal events or unacceptable risk early, take appropriate risk management measures promptly, in order to avoid the occurrence of accidents or incidents.

2 The Establishment of Airport Operational Safety Risk Monitoring Indicators

The airport operational safety risk monitoring indicators are not limited to high consequence (safety results) indicators; also include low consequence (operational process) indicators to reflect the operation state and safety management indicators. Therefore, the indicators can systematically and scientifically evaluate the safety state of an organization, and the results can reflect the safety results while expose the problems in the process of operation and management.

2.1 The Method of Designing Safety Risk Monitoring Indicator

  1. (1)

    The method of designing low consequence (operational process) indicators

The method of designing low consequence (operational process) indicators includes the following two categories.

  • Forward analysis method

The first step of forward analysis method is to decompose and analysis system and processes, then identify the hazards may lead to the unusual process, further deduce unusual activities or status, until the final consequences of danger (As Fig. 1.). Then the abnormal activity or status can be designed as low consequence indicators. The analysis methods from the hazards to the dangerous consequences include the event tree analysis (ETA), hazard and operability analysis (HAZOP), What-if analysis, etc.

Fig. 1.
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Forward analysis method

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  • Reverse analysis method

Inverse analysis method is defined from the dangerous consequences (such as runway incursion etc.) to the beginning state. To analysis the unsafe activities or status, and the direct and indirect causes. Then the abnormal activity or status can be designed as low consequence indicators (As Fig. 2.). The analysis methods from the dangerous consequences to the hazards include the fault tree analysis (FTA), Reason model, SHELL model, etc.

Fig. 2.
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Reverse analysis method

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  1. (2)

    The method of designing safety management indicators

Design of safety management indicators can be carried out in accordance with the safety management system elements method and system elements method.

Safety management system elements method means that we can design indicators to measure the implementation and construction of the SMS’s 12 elements. For example, in view of management commitment, we can design the indicator “safety committee attendance rate”.

The system elements method means that we can design indicators to elements of system including responsibility, authority, procedures, tools/method, personnel, implementation, control and effect. For example, in view of implementation of the safety inspection work, we can design the indicator “safety inspection work completion rate”.

2.2 The Design of Airport Operational Safety Risk Monitoring Indicators

This research first identifies ten key modules that can influence airport operation risk, including the runway unseaworthiness, navigation facilities failure, obstacle clearance excessive, runway incursion, flight area perimeter intrusion, vehicles and aircraft scratching, FOD, bird strike, hidden load and hazards of non-stop flight construction.

Then, we analyze the possible hazards of the ten key modules, establish the low consequences indicators through the forward analysis method and the safety management indicators based on the system elements method. We also design the high consequence indicators through analyzing China civil aviation incidents standard terms associated with the ten key modules. Specific process is as follows:

  1. (1)

    The design of the low consequences indicators and the safety management indicators

  • Initial design

We design the low consequences indicators and the safety management indicators based on the ten key modules firstly.

  • Airport survey

We go to an airport, organize the relevant experts to analyze the applicability of indicators. Then, we revise the risk monitoring indicators.

We develop the ten key modules risk monitoring indicators questionnaire after the initial risk monitoring indicators are formed, and collect 12 airports questionnaires.

  • Revise and improve the indicators

The returned questionnaires are analyzed. We analyze the airports disagreement based on the principle of majority and the final low consequences indicators and safety management indicators are formed.

Take the vehicle and aircraft scratching module for example, part of the low consequences indicators and safety management indicators final formed are as shown in Table 1.

Table 1. Part of the vehicles and aircraft scratching module’s low consequences indicators and safety management indicators.
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  1. (2)

    The design of the high consequences indicators

The standard terms of incidents and occurrences associated with the ten key modules are identified based on the China “Civil aircraft incidents standard” and “Civil aviation occurrences sample”. These incidents and occurrences identified formed the ten key modules related high consequence indicators.

Take the vehicle and aircraft scratching module for example, the high consequence indicators associated with this module include: The incidence of aircraft and aircraft, vehicles, equipment and facilities scratching that damage the aircraft; the incidence of aircraft and aircraft, vehicles, equipment and facilities scratching.

  1. (3)

    Integrating various types of safety risk monitoring indicators

We integrated all the indicators to form the various types’ indicators including high consequences indicators, low consequences indicators and safety management indicators associated with the ten key modules. Through the survey of the two airports, the safety risk monitoring indicators are analyzed, screened and improved; finally 165 airport operational risk monitoring indicators are established.

3 The Establishment of Airport Operational Risk Alerting Model

3.1 Principle

  1. (1)

    Risk assessment principle

Safety risk is the combination of possibility and severity of the consequence or outcome from an existing hazard or situation.

On the basis of hazard identification and analysis, risk assessment evaluates the possibility of risk and the harm degree. Comparing with the safety standards, it can measure the risk level, and help us to determine whether to need to take corresponding measures. According to this principle, the key step of risk assessment is the comprehensive assessment of the likelihood and the severity of risk events, and then it needs to establish an acceptable level of safety standards.

The principle of risk assessment can provide theoretical foundation and concrete ideas for the airport operational risk alerting model.

  1. (2)

    Heinrich’s Law

Heinrich’s Law was provided by Herbert William Heinrich in 1931. It became known as that in a workplace, for every accident that causes a major injury, there are 29 accidents that cause minor injuries and 300 accidents that cause no injuries. Because many accidents share common root causes, addressing more commonplace accidents that cause no injuries can prevent accidents that cause injuries.

Although this analysis will vary by the improvement of aircrafts’ reliability and the management ability, it still illustrates the inevitable link between accidents and safety. Heinrich’s Law is a warning for us. It shows that any accident has a reason and previous signs. On the other side, it tells us safety can be controlled, and the disaster can be avoided, It also gives us a method of safety management, which is finding and controlling the symptoms before bad consequences.

The Heinrich’s Law can be used to prove the importance of lower-consequence indicators, and to establish the index of various indicators’ severity.

  1. (3)

    Safety performance management

The basic principle and methods of safety performance management is elaborated more in “safety management manual (ICAO’s Doc9859), it propose the indicators for monitoring and evaluation organization safety status should include not only high consequence indicators, but also include low consequence indicators, and it gives the setting methods of safety performance indicators’ target and alert level.

We use one incident rate per million flights at the airport as an example.

  1. (1)

    Alert level setting

The alert level for a new monitoring period (current year) is based on the preceding period’s performance (preceding year), namely its data points average and standard deviation. The three alert lines are average + 1 SD, average + 2 SD and average + 3 SD.

  1. (2)

    Alert level trigger

An alert (abnormal/unacceptable trend) is indicated if any of the conditions below are met for the current monitoring period (current year):

  • Any single point is above the 3 SD line;

  • 2 consecutive points are above the 2 SD line;

  • 3 consecutive points are above the 1 SD line.

When an alert is triggered (potential high risk or out-of-control situation), appropriate follow-up action is expected, such as further analysis to determine the source and root cause of the abnormal incident rate and any necessary action to address the unacceptable trend.

3.2 The Airport Operational Risk Alerting Model

According to the above principle and the characteristics of the airport operation, the research needs these six steps to set up integrated Airport Operational Risk Alerting Model.

  1. (1)

    Establish the layer of risk alerting model

The risk alerting model has three layers at least in our research as Fig. 3. The bottom layer calculate the different modules’ risk that needs to use the indicator including high consequence indicators and low consequence indicators, the middle layer synthesize all modules’ risk as one index for single airport, and finally, the upper layer synthesize all airport’ risk as one index for an airport group.

Fig. 3.
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Airport group risk alerting index model

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  1. (2)

    Assignment the severity weight of different indicators’ corresponding event

Based on the principle of risk evaluation, safety risk is the combination of possibility and severity of the hazard. In our research, the possibility is the frequency of the happening, but the severity of the event needs to be standard uniformed and quantified.

Based on the China “Civil aircraft incidents standard” and “Civil aviation occurrences sample”, the experts give different score according to the influence degree of the possible consequences. The score range is showed in Table 2.

Table 2. The severity weight range of various indicators
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  1. (3)

    Define the severity coefficient of indictors

According to Heinrich’s Law, the frequency of the events is 1:1/29:1/300:1/1000, we define the reciprocal of the frequency as severity coefficient, which means the severity coefficient of severe flight incidents, General flight incidents and ground incidents, Occurrence/safety management corresponding event and Low consequence corresponding event is 1000,35,3and1respectively. Use this method, we collect and analyze one airport group data from 2011-2014 to adjust the coefficient suitable for the real operation. Finally, we get the coefficient of severity is 4600:460:10:1

  1. (4)

    Calculate monthly different modules’ risk score

The modules’ risk score is the sum of the indictors’ corresponding events risk score.

  1. (5)

    Calculate monthly risk index of single airport I

I = the sum of different modules’ risk score/air traffic movements.

  1. (6)

    Calculate monthly risk index for airport group Is

Is is the average of all members of airport group risk index.

3.3 Example

The research picks two airport data for analysis, the actual operation data are collected from Aug to Oct, 2015. After calculating, the research gets the result as Table 3 shown.

Table 3. Monthly risk index of single airport
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If we want to set the alert line or section, we need the data before the Aug. Thus, we give the virtual severity and risk index of airport A from Jan to Jul as Table 4 shown.

Table 4. Virtual Severity and Risk Index of airport A from Jan. to Jul
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According the setting methods of safety performance indicators’ target and alert level:

The average of airport A is 23.08, and the SD is 4.38, and

Average + 1 SD = 27.46;

Average + 2 SD = 31.84;

Average + 3 SD = 36.21.

The research assumes that the risk below 27(including 27) for green zone, 27-32 for yellow zone, 32-37 for orange zone, and above 37(including 37) for red zone. Based on the different zone, the research draw the Aug., Sep. and Oct.’s risk index as Fig. 4 shown.

Fig. 4.
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Airport A’s safety risk index

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Use the same method, the research can draw the Aug., Sep. and Oct.’s severity as Fig. 5 shown.

Fig. 5.
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Airport A’s severity values

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4 Conclusion and Recommendations

In summary, this research establishes the airport operational safety risk indicators based on the safety risk management theory and safety performance management theory. The airport operational risk alerting model is also established based on the Heinrich’s Law, risk assessment principles and historical data of an airport group. This model is verified to be applicable through three months data collection, calculation and risk warning of two airports.

On the one hand, this research can be used of the more comprehensive scientific assessment of airport operational risk and warning to find the abnormal events or unacceptable risk to take preventive measures timely. On the other hand, it can also help to improve airport information reporting standards, in order to obtain more comprehensive operational process data.