Safety Science 75 (2015) 72–86

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Safety Science

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Performance evaluation of airport safety management systemsin Taiwan

http://dx.doi.org/10.1016/j.ssci.2014.12.0060925-7535/� 2014 Elsevier Ltd. All rights reserved.

⇑ Corresponding author. Tel.: +886 6 278 5123x2251; fax: +886 6 278 5056.E-mail addresses: yhchang@mail.ncku.edu.tw (Y.-H. Chang), peishao@hotmail.

com (P.-C. Shao), hjpcheney@yahoo.com (H.J. Chen).1 Tel.: +886 6 275 7575x53271 4030; fax: +886 6 275 3882.2 Tel.: +1 706 850 7393.

Yu-Hern Chang a,1, Pei-Chi Shao b,⇑, Hubert J. Chen c,2

a Department of Transportation and Communication Management Science, National Cheng Kung University, 1 University Road, Tainan 701, Taiwanb Department of Aviation and Maritime Transportation, Chang Jung Christian University, 1 Changda Road, Tainan 711, Taiwanc Department of Statistics, University of Georgia, Athens, GA, USA

a r t i c l e i n f o

Article history:Received 13 November 2013Received in revised form 14 October 2014Accepted 10 December 2014

Keywords:Airport SMSRisk managementANPFuzzy TOPSIS

a b s t r a c t

To comply with the International Civil Aviation Organization’s requirements, all certified airports wererequired to implement and operate a Safety Management System (SMS) from November 2005. This studyused a two-stage process to evaluate the performance of the SMS operations at Taiwan’s Taoyuan (TPE),Kaohsiung (KHH), and Taipei Songshan (TSA) international airports. The first stage was to acquire theweights and rankings of the SMS components and elements using the Analytic Network Process (ANP),and the second stage was to evaluate and rank their performance using the fuzzy Technique of OrderingPreference by Similarity to Ideal Solution (TOPSIS). The rankings of SMS weights of components from highto low are: Safety risk management, Safety policy and objectives, Safety promotion, and Safety assurance. Instage two, we combined all evaluations of the components. The overall SMS performance ranking of thesethree international airports was TPE (1st), KHH (2nd), and TSA (3rd). The findings of this research shouldprovide aviation authorities and airport administrators in Taiwan with directions for safety risk manage-ment and allocation of materials and resources to conduct safety training in order to prevent aviationaccidents.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction occurrences for that period were nine runway excursions and

According to a recent study (Shao et al., 2013), between 2002and 2011 in Taiwan, the average accident rate (per million depar-tures) involving turbojet aircraft hull loss was 2.57 times theworld’s average (Civil Aeronautics Administration [CAA] 2012);the average rate of hull losses on commercial jets was 1.75 per mil-lion departures, and on turboprop aircraft was 1.31 (CAA, 2012).The International Civil Aviation Organization (ICAO) recommendedsafety targets that include reducing fatal airline accidents, seriousincidents, runway excursions, and ground collisions (ICAO,2009a). These safety targets were announced in Taiwan by the Tai-wan CAA (2011a). Finally, the state safety program was imple-mented on December 17, 2012.

Based on the ICAO Occurrence Categories (ICAO, 2008) and Tai-wan Aviation Safety Council (ASC) Accident/Serious Incident classi-fication, this study looks back to the aviation safety statistics from2002 to 2011 in Taiwan (ASC, 2012). The airport safety-related

one ground collision, which indicated a poor safety performancecompared with ICAO safety targets in reducing runway excursionevents and ground collisions (ICAO, 2009a; CAA, 2011a; Shaoet al., 2013). These two types of accidents occurred on airport run-ways during aircraft takeoffs and landings. Runway safety is the‘‘one of aviation’s greatest challenges worldwide’’ (United StatesFederal Aviation Administration [FAA] 2010). Airport Safety Man-agement Systems (SMSs) are extremely important for airportsafety (including runway safety).

According to the ICAO Safety Management Manual (SMM)(ICAO, 2009a), an SMS is defined as ‘‘a management tool for themanagement of safety by an organization’’. An airport SMS is asafety management system for airports. In accordance with theICAO SMM, Annex 14 (ICAO, 2009b), and Civil Aerodrome Designand Operation Standards (CAA, 2011b), the airport SMS frameworkincludes four components and twelve elements that constitute theminimum requirements of SMS implementation. The implementa-tion of the SMS framework must correspond to the size of the air-port and the complexity of the airport service provider.

Because runway excursions and ground collisions are related toairport safety, airport SMS operations must not only comply withICAO requirements, but also improve airport safety. This researchinvestigated airport SMS performance in Taiwan. Most prior

Y.-H. Chang et al. / Safety Science 75 (2015) 72–86 73

academic studies on SMSs for the aviation industries were intendedto establish or to discuss airline SMS components (McDonald et al.,2000; Liou et al., 2008; Hsu et al., 2010); few were related to airportsurface safety indicators and airport SMSs (Cardoso et al., 2008;Wilke et al., 2012). With regard to recent aviation industrial SMSresearch, McDonald et al. (2000) used a self-regulatory model toillustrate the relationships of safety climate and SMSs in the fouraircraft maintenance organizations; Liou et al. (2008) developedSMS factors which used an effective airline SMS model to map outthe relations among diverse factors and to identify the key safetyfactors; Cardoso et al. (2008) established the Individual Perfor-mance Indicators (IPIs) and Overall Performance Indicators (OPIs)to evaluate the SMS performance on airport surfaces and ramps;Hsu et al. (2010) identified the key components of an airline SMSand discussed the interactions between the key components amongthe aviation organizations and authorities; Wilke et al. (2012)focused their holistic taxonomy on critical factors of airport surfacesafety occurrences that can support the safety risk managementoperations of SMS using data analysis. Current aviation SMSresearch focuses on the SMS components to establish SMS perfor-mance indicators or to implement SMS influences in organizations,but it does not evaluate SMS performance for the overall system(e.g. airport SMS). Thus, in this paper, the overall SMS system is con-sidered and airport SMS performance evaluated.

According to SMM Section 6.6.8: ‘‘the safety performance targetshould be obvious, measureable, and acceptable to stakeholdersand linked to the safety performance elements’’ (ICAO, 2009a).For this reason, in this paper the stakeholders (academics, airlineindustry managers, and governmental assessors) are necessary toevaluate a target airport’s SMS performance. In academic researchfor SMS stakeholders, Wilke et al. (2012) used the viewpoint of avi-ation stakeholders (e.g., regulators, airport authorities, airlines,ground handlers, and accident investigation boards) to developthe airport surface occurrence taxonomy and to evaluate the air-port surface safety performance. In Taiwan’s airport SMS loop,the Taiwan CAA (governmental experts) is the SMS legislator andsupervisor, and aviation industries (airports and airlines) are theSMS executors, and academic experts are analysts of SMS perfor-mance and safety records.

Airport SMSs are important for state safety programs, but thereare few studies that evaluate SMS performance. Therefore, thisresearch used Fuzzy TOPSIS (Fuzzy Technique of Ordering Prefer-ence by Similarity to Ideal Solution) to evaluate the SMS perfor-mance of Taiwan’s Taoyuan (TPE), Kaohsiung (KHH), and TaipeiSongshan (TSA) international airports through questionnaire sur-vey by experts who have been working in the airline industry, aca-demics, and government, respectively; to compare their SMSperformance using the weighted average method; and, then, todetermine the rank order of their SMS performance. Based on therankings, the top SMS managers of these three international air-ports were interviewed to verify the ranking order of their SMSperformance, which confirmed our results. Finally, the conclusionsof the research are discussed.

2. SMS literature review

Because airport SMS is a recently developed concept, the litera-ture that directly discusses it is limited (Cardoso et al., 2008). Air-port SMS legislation history and regulations and some recentresearch will be discussed in this subsection.

2.1. Airport SMS regulations

To improve airport safety, the ICAO published and implementedthe airport SMS in November 2005, and the initiative state agencies

included the Civil Aviation Safety Authority (CASA) in Australia, theU.S. Federal Aviation Administration/Airport Council Research Pro-gram/Transportation Research Board (FAA/ACRP/TRB), TransportCanada Civil Aviation (TCCA), and the United Kingdom Civil Avia-tion Authority (UK CAA) (Cardoso et al., 2008). These countriesuse ICAO airport SMS requirements as the main framework fortheir airport SMS documents.

In 2009, the ICAO published the Standards and RecommendedPractices for the state safety program, which declares that the con-tracting states shall establish their state safety program. Taiwancompleted the first edition of its State Safety Program (CAA,2011a) and complied with the requirements of ICAO Annex 14 toimplement an airport SMS. The Taiwan CAA not only describedthe SMS framework in its Civil Aerodrome Design and OperationStandards Appendix 7 (CAA, 2011b), but also complied with theICAO SMM requirements of establishing an airport SMS for theannual renewal of aerodrome certificates.

The ICAO airport SMS is a requirement for a certificated aero-drome; it is referred to as the regulations for an airport SMS anduses four components and twelve elements for an airport SMS per-formance evaluation. The regulations are based on the ICAO SMM(ICAO, 2009b), Civil Aerodrome Design and Operation Standards:Appendix 7 Framework for SMS (CAA, 2011b), FAA AC (AdvisoryCircular) 150/5200-37 (FAA, 2007), and ACRP Report 1: SafetyManagement System for Airports (TRB, 2007). The descriptionsand structure of Taiwan’s SMS are summarized in Appendices Aand B, and the Taiwan Airport SMS performance evaluation struc-ture is shown in Fig. 1.

2.2. The aviation industry’s SMS literature

McDonald et al. (2000) researched the safety culture, safety cli-mate, and SMSs of four aircraft maintenance organizations. Theirrevised SMS model not only describes the sequence and cycle ofthe elements, but also illustrates the coordination between the dif-ferent elements in each organization. After the ICAO publishedSARPs and the SMS in 2005, academic research began to discussthe influence and importance of SMS components and elementsfor airlines. Hsu (2008) used the Flight Management AttitudesQuestionnaire (FMAQ) to analyze the SMS to determine the criticalorganizational factors that affect the proactive safety of the crew.The critical organizational factors include: Crew safety complianceand participation, Managerial decisions, the Operational system,Communication, and Management leadership and commitment.

Liou et al. (2008) developed SMS factors by reviewing regula-tions (e.g., US AC120-92, UK CAP712, and Taiwan CAA AC-120-32A). The Delphi method was used to collect the advice of expertsand to develop the SMS factors, and then the relationships betweenthe SMS factors were uncovered using the fuzzy DEMATEL (Deci-sion Making Trial Evaluation Laboratory) method. The DEMATELImpact-Relations Map (IRM) was used to determine the safety tri-angle and the degrees of relatedness of the SMS factors. They alsopointed out that the ‘‘Strategy and Policy’’ group of SMS factors wasat the top of the safety triangle in the IRM and that it was the mostimportant SMS factor.

Hsu et al. (2010) built a critical airline SMS framework, and theyprobed the relationships and importance of SMS components andelements using a hybrid method constructed from a synthesis ofGray Relational Analysis (GRA), DEMATEL, and the Analytic Net-work Process (ANP). The SMS framework was extracted from reg-ulations and the advice of experts using the GRA 0.75 thresholdvalue. The results of the ANP for the weighted ranking of the topfive components were Safety policy, Safety culture, Communica-tion, Training-awareness and competence, and Identification andmaintenance of applicable regulations. Hsu et al. also argued that‘‘Safety policy’’ and ‘‘Safety objective and goals’’ were airline safety

Air

port

Saf

ety

Man

agem

ent S

yste

m P

erfo

rman

ce E

valu

atio

n in

Tai

wan

C3 Safety assurance

e31 Safety performance monitoring and measurement

e32 The management of change

e33 A non-punitive safety reporting system

e34 Continuous improvement of the SMS

e21 Hazard identification

e22 Safety risk assessment systemC2 Safety risk management

e23 Safety risk mitigation strategies

e11 Management commitment and responsibility

C1 Safety policy and objectives e13 Appointment of key safety personel

e12 Safety accountability

e15 SMS documentation

e23 To implement, track and monitor the safety risk mitigation

C4 Safety promotion

e41 Safety culture

e42 Training and education

e43 Safety communication

e44 Safety competency and continuous improvement

e14 Coordination of emergency response planning

Fig. 1. Taiwan airport Safety Management System performance evaluation structure.

74 Y.-H. Chang et al. / Safety Science 75 (2015) 72–86

targets for their core business function and a minimally acceptablesafety level for airline authorities and she concluded that thedimension of ‘‘Organization’’ had the highest positive effect in animpacted-direction map (IMP). Thus, the ‘‘Organization’’ of airlinesis the largest net generator of effects and is the most importantdimension in an airline SMS.

2.3. Aviation safety performance evaluation

Chang and Yeh (2004) presented a new airline safety index,which was based on proactive safety measures, and developedgeneralizations from the literature. The analytic hierarchy process(AHP) was used to obtain the relative weights of the safety index

and the hierarchical framework for safety levels. Because the attri-butes of some safety indices are qualitative and conflicting, amulti-attribute decision-making (MADM) method was used. Thus,Chang and Yeh (2004) used a fuzzy MADM method to ask expertsto evaluate airline safety performance with a fuzzy linguistic mea-sure. To avoid the unreliable process of comparing fuzzy numbers,they assumed that a general concept of MADM arrived at via thebest alternative should have the shortest distance from the positiveideal solution (PIS) and the longest distance from the negative idealsolution (NIS).

To reflect the relationships and degree of dependence betweenairline safety factors, Liou et al. (2007) used a hybrid model ofDEMATEL and ANP to illustrate the interdependence and feedback

Y.-H. Chang et al. / Safety Science 75 (2015) 72–86 75

of safety factors. The airline safety measurements were arrived atby consulting with experts and analyzing regulation referencesthat included four dimensions and eleven criteria. The airlinesafety measurement weights and importance were determinedusing the ANP, and the airline safety performance values wereobtained using the weighted sum method (WSM).

In practical safety operation research, Cardoso et al. (2008) andWilke et al. (2012) focused on airport airside, surface, and rampsafety performance indicators developing and evaluation.Cardoso et al. (2008) said that airport SMS performance monitoringis based not only on the number of accidents and loss of life, butalso considers latent conditions and near-miss events. Cardosoet al. (2008) used airside individual performance indicators (IPIs)and overall performance indicators (OPIs) for airport SMS. The IPIswere developed and validated by airport operators in South Amer-ica according to ten priority groups. Cardoso et al. (2008) focusedon airside accidents (e.g., runway incursions, aircraft bird/wildlifestrikes, incidents on each runway, and foreign object damage/for-eign object debris (FOD). They assumed that the IPIs should be lim-ited to a one-year period, but averaged or estimated for 10,000aircraft operations depending on airport size. The WSM was usedfor IPIs where they were used to multiply the weights to obtainOPI values.

Wilke et al. (2012) developed a new holistic taxonomy of criti-cal factors of airport surface occurrences ‘‘from the viewpoints ofall the relevant aviation stakeholders (regulators, air navigationservice providers, airport authorities, airlines, ground handlingcompanies, accident investigation boards)’’ to evaluate airportsafety performance using a multinational data analysis. In theirwork, using taxonomy can support the safety risk managementin airport SMS operations, which is structured into five categories:Aircraft Operations, Air Traffic Control, Airport Operations, Envi-ronment, and Regulatory System. After applying their taxonomyto a multinational data set, they found that the differencesbetween nations through the combined use of the data sets werea function of the national air traffic system and airport infrastruc-ture, underlying regulations, reporting system, and safety culture,and the viewpoints of the aviation stakeholders.

Table 1Verbal judgment scale of the analytic network process (ANP). Source: Saaty (1980).

Verbal judgment Numericalvalues

Equal 1Marginally strong 3Strong 5Very strong 7Extremely strong 9Intermediate values to reflect fuzzy inputs 2,4,6,8Reflects dominance of the second alternative compared

with the firstReciprocals

3. Methodologies

A review of the aviation SMS and safety assessment literatureshows that most researchers used the multiple criteria decisionmaking (MCDM) method to develop the safety dimensions andsafety criteria (Chang and Yeh, 2004; Liou et al., 2007, 2008;Cardoso et al., 2008; Hsu et al., 2010). Chen and Klein (1997)pointed out that fuzzy MADM was developed because of the lackof precision in assessing the relative importance of alternativesand the performance ratings of alternatives with respect to anattribute. Because the fuzzy MADM sources are imprecise (i.e., theyhave unquantifiable, incomplete, and unobtainable information(Chen and Hwang, 1992)), the fuzzy MADM method is used to eval-uate airport SMS performance based on the attributes of theresearch objectives.

Using an ANP method developed by Saaty (1996), recent avia-tion safety research has studied the relationship and effectsbetween safety factors, safety indices, and safety criteria(McDonald et al., 2000; Liou et al., 2007, 2008; Hsu et al., 2010)to determine the dependence and feedback between the criteriaand alternatives of problems. Based on the literature and theadvice of experts, the present study determined airport SMS com-ponents and the weights and importance of their elements. Toinvestigate the character of decision-making problems in real life,the fuzzy MADM method is used to evaluate the ratings andweights of criteria for imprecision, subjectivity, and ambiguity

using linguistic variables and fuzzy numbers (Zimmermann,1996). The fuzzy MADM method has been widely applied to solveaviation industry decision-making problems (Borenstein andZimmerman, 1988; Chang and Yeh, 2002, 2004; Wang andChang, 2007; Fernandes and Pacheco, 2007; Chou et al., 2011;Torlak et al., 2011). In this research, components and elementsused to evaluate the performance of an airport SMS were estab-lished by reviewing ICAO-, Taiwan CAA-, and U.S. FAA-certified air-port regulations. Based on the imprecise character of airport SMScomponents and elements such as unquantifiable, incompleteinformation (Chen and Klein, 1997), their qualitative measureshave uncertain multiple attributes. Therefore, based on the natureof airport SMS operations and performance evaluation, this studyintended to solve a MADM problem. The research was done inthe two stages described below.

The first stage: Based on the characteristics of an airport SMS forhierarchy, feedback, and loops, this research used the ANP to deter-mine the weights of airport SMS components and elements at thisstage. The performance evaluation components and elements of anairport SMS were developed using a literature review. Theirweights and importance were obtained using the ANP to analyzethe subjective assessments of experts.

The second stage: Because of the lack of perception in assessingthe relative importance and performance ratings of alternativeswith respect to an attribute (Chen and Klein, 1997), this researchused the popular fuzzy MADM method (Zhang, 2004) for the fuzzyTOPSIS to evaluate the SMS performance of TPE, KHH, and TSAinternational airports in Taiwan. Comparisons between the SMSperformance evaluations of these three airports were then made.Based on the findings, the top SMS managers at TPE, KHH, andTSA international airports were interviewed to verify the resultsand to understand the actual airport SMS operations.

3.1. Performance using the analytic network process

The analytic hierarchy process (AHP), which was proposed bySaaty in 1971, was used to solve the MADM problem, and a linearhierarchical structure was used to describe the relationshipbetween components and elements. Saaty believed that, in real life,the components and elements of problems are dependence andfeedback relations; therefore, in 1980 he introduced the ANPmethod to solve such problems (Saaty, 2008). The ANP structurelooks like a nonlinear network, and the components and elementsof the connections are dependent. The weights and, therefore, thepriorities of the components and elements are derived by usingpairwise comparison matrices that come as parts of columns of asupermatrix. The verbal judgment scale of an ANP is divided intofive levels to reflect their relative importance (Table 1).

The ANP can be illustrated by the following steps (Azimi et al.,2011).

Step 1: Decomposing the problem as a model structure

76 Y.-H. Chang et al. / Safety Science 75 (2015) 72–86

Based on the literature, the knowledge of experts, and the nat-ure of a research topic, the problem is decomposed into a goal,components, and the elements to form a model. The weights areproduced for all components for the dependencies related to anoverall set of criteria in an investigation by an expert or experts.

Step 2: Pairwise comparison matrices

According to the model structure, each component and elementis compared with each other component and element to obtain therelative importance to form pairwise comparison matrices. The rel-ative importance values are determined using Saaty’s 1-9 scale(Table 1) (Saaty and Vargas, 2006). The relative importance ofgroup judgments is aggregated using the geometric mean beforethe pairwise comparison matrices can be established (Saaty, 2008).

Step 3: Supermatrix formation

At this stage, the limiting priorities of the influence are con-structed using a supermatrix. To obtain the priorities, the sum ofeach column of the supermatrix must be transformed to unity,which simply turns it into a stochastic matrix (Saaty and Vargas,2006). The concept of the supermatrix is similar to that of a Markovchain process; Saaty developed the supermatrix to synthesize ratioscales for the ANP (Saaty, 1996). Let the components of a decisionsystem be C1,C2, . . .,Cn, and let the lth component have pl elements,l = 1,2, . . .,n, denoted by el1, el2, . . ., elpl

. The influence of a set of ele-ments under a component, on any element from another compo-nent, can be represented by a priority vector (called aneigenvector) by using the pairwise comparison technique. Thesepriority vectors are grouped and located in appropriate positionsin a supermatrix based on the flow of influence from one compo-nent to another component, or from one component to itself (asin a loop). A standard form of the supermatrix used in this studyis shown in Fig. 2, where Wij is a submatrix of principal eigenvec-tors of the influence of the elements in the ith component (Ci) con-nected to the jth component (Cj). For example, in Fig. 2, W11

represents the sub-matrix with p1 elements under component 1(C1) as denoted by e11, e12, . . ., elpl

, which are located under C1 andto the left side of the supermatrix. If the ith component has no influ-ence or no correlation with the jth component, then the submatrix

1

1

1 1

2 1

1

1

1 1 1 2 1 2 1 2 2

1 1

1 2

1

1

2 1

2 22

2

1

2

n

n

p

p

p

n

nn

n p

Ce e e e e

ee

C

eee

C

e

eeC

e

W

WW

W

=

Fig. 2. Super

Wij = 0, where 0 is a zero matrix. The form of the supermatrixdepends on the nature of its structure. The submatrix Wij, (i – j),is multiplied by the weight Cij of the influence from componentCi to component Cj, where (Ci1,Ci2,Ci3,Ci4) is the principal eigenvec-tor (weights) of the comparison matrix formed with Ci as a leadingcomponent relative to all others. Note that, in this study, all col-umns in Wij have the same principal eigenvectors. The submatrixWii stands for the feedback matrix within the ith component. Inthis way, the elements in each column of the supermatrix areweighted and they are summed to one. The weighted supermatrixshould be raised to the power of 2k + 1 (k is any arbitrarily largenumber) to have the weights converged (Saaty, 1996), becauseraising exponential powers to the supermatrix provides stable rel-ative influences of the elements on each other, i.e., places a limitingvalue on W, e.g., limk?1 W2k+1, to obtain the long-term relativeweights (Saaty, 1996).

Step 4: Selecting the important elements and components

If the supermatrix includes only components that are interre-lated, additional calculations must be made to obtain the overallpriorities. The element or component with the largest weightshould be selected, because it is the most important element orcomponent, as determined by the calculations of the supermatrix(Fig. 2).

3.2. Performance by Fuzzy TOPSIS

The TOPSIS method, developed by Hwang and Yoon (1981), is aMADM method (Zhang, 2004). The main concept of TOPSIS is com-paring MCDM criteria and checking whether a judgment of a com-ponent has the shortest distance from the positive ideal solution(PIS) and the farthest distance from the negative ideal solution(NIS). MCDM problems are related to vague criteria and the subjec-tive opinions of decision makers. To solve the qualitative, impre-cise, and ill-structured decision problems, Zadeh (1965) proposedthe theory of fuzzy sets, and suggested using this theory to solvecomplex system problems. In real life, human judgments expresspreferences, are subjective, and are vague (Chen, 2000). Therefore,linguistic assessments are widely used to evaluate elements usingqualitative criteria (Table 2). The main purpose at this stage is to

2

1 2 1

2 2 2

2

2

2 1 2 n

n

n

n n n

n

n pp n n

C Ce e e e

W W

W W

W W

matrix.

Table 2Performance by linguistic variables for a component or an element.

Linguistic variables Very low Low Medium High Very high

Performance Score (1, 1, 3) (1, 3, 5) (3, 5, 7) (5, 7, 9) (7, 9, 9)

Y.-H. Chang et al. / Safety Science 75 (2015) 72–86 77

evaluate the airport SMS performance by components and ele-ments for TPE, KHH, and TSA. Stage two uses the expert question-naires to obtain the airport SMS performance scores usinglinguistic variables for each component and element (Table 2).

Based on the qualitative nature of airport SMS components andelements, this study used fuzzy TOPSIS to solve the performanceevaluation of airport SMS for TPE, KHH, and TSA international air-ports. The steps of fuzzy TOPSIS are described as follows (Chen,2000).

Step 1: Construct the fuzzy decision matrix

Assume that there are m international airports (or systems)denoted by Ai (i = 1,2, . . .,m) and n elements associated with eachset of airport SMS performance assessments denoted by Ej

(j = 1,2, . . .,n). Then, the fuzzy decision matrix can be expressedin matrix form as in Eq. (1):

ð1Þ

where ~aij ¼ aðLÞij ; aðMÞij ; aðUÞij

� �is the performance rating assessed by

linguistic fuzzy triangular sets of the ith international airport Ai withrespect to the jth elements Ej: (i = 1,2, . . .,m) and (j = 1,2, . . .,n). Note

that the items in the triplet aðLÞij ; aðMÞij ; aðUÞij

� �represent the aggregate

values of the fuzzy triangular lower, medium, and upper numbersobtained from a group of experts. In our study, n = 17, E1–E5 standsfor elements e11–e15 under component C1, E6–E9 for e21–e24under component C2, E10–E13 for e31–e34 under component C3,and E14–E17 for e41–e44 under component C4.

Step 2: Construct the weighted fuzzy normalized decisionmatrixBased on the natures of each airport SMS’s components and ele-

ments, this study constructed a weighted, fuzzy, normalized deci-sion matrix. The weights of the components and elements wereobtained using the ANP (discussed in Section 4.1). The weighted

normalized decision matrix eV is defined as:

eV ¼ ½~v ij�m�n; i ¼ 1;2; . . . ;m; j ¼ 1;2; . . . ;n ð2Þ

where

~v ij ¼ ~aij � ~wij ð3Þ

and ~wij is weight of component Cj associated with airport Ai

obtained from limiting the supermatrix, and ~v ij ¼ v ðLÞij ;vðMÞij ; v ðUÞij

� �:

Step 3: Determine the fuzzy positive idea solution (FPIS) andfuzzy negative idea solution (FNIS)Before acquiring the FPIS and FNIS, defuzzification should be

done, and then the size of the fuzzy sets should be compared andthe largest and smallest sets obtained to acquire the FPIS and FNIS.This study used the common method for center of gravity defuzz-

ification (CGD) (Yager, 1980) (Eq. (4)). That is, take the average ofthe numbers in the aggregate fuzzy set:

Bð~v ijÞ ¼v ðLÞij þ v ðMÞij þ v ðUÞij

� �3

ð4Þ

For this step, the FPIS and FNIS are defined as:

FPIS : A� ¼ ð~v�1; ~v�2; . . . ; ~v�nÞ;Bð~v�j Þ ¼maxi

Bð~v ijÞ; j ¼ 1;2; . . . ;n

ð5Þ

FNIS : A� ¼ ð~v�1 ; ~v�2 ; . . . ; ~v�n Þ;Bð~v�j Þ ¼mini

Bð~v ijÞ; j ¼ 1;2; . . . ;n:

ð6Þ

Step 4: Calculate the distance of each airport SMS element toFPIS and FNIS by using the distance of each element from A⁄

and A� as calculated using:

FPIS : d�i ¼Xn

j¼1

dð~v ij; ~v�j Þ; i ¼ 1;2; . . . ;m; ð7Þ

FNIS : d�i ¼Xn

j¼1

dð~v ij; ~v�j Þ; i ¼ 1;2; . . . ;m; ð8Þ

where dð�; �Þ is the distance measurement between two fuzzy sets ofnumbers as defined in:

FPIS : d�i ¼Xn

j¼1

dð~v ij; ~v�j Þ

¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi13

v ðLÞij � v� ðLÞj

� �2þ v ðMÞij � v� ðMÞj

� �2þ v ðUÞij � v� ðUÞj

� �2� �s

ð9Þ

FNIS : d�i ¼Xn

j¼1

dð~v ij; ~v�j Þ

¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi13

v ðLÞij � v�ðLÞj

� �2þ v ðMÞij � v�ðMÞj

� �2þ v ðUÞij � v�ðUÞj

� �2� �s

ð10Þ

where d�i and d�i are, respectively, the FPIS and FNIS for the ith sys-tem (airport).

Step 5: Obtain the closeness coefficient (CC), and then rank theorder of airport SMS elementsA CC is used to determine the ranking order of all airports once

the d�i and d�i for each airport have been calculated. The CC of the ith

airport is defined as:

CCi ¼d�i

d�i þ d�i; i ¼ 1;2; . . . ;m: ð11Þ

The value of CCi lies in the interval of (0,1), which implies thatan airport (Ai) is closer to the FPIS (A⁄) and farther away from theFNIS (A�) as the value of CCi approaches 1. Therefore, using thecloseness coefficient, we can easily determine the rank order ofall airports and select from them the best one.

4. Empirical study and results

Based on the objective of the research, the airport SMS perfor-mances of TPE, KHH, and TSA international airports were evaluatedby experts in the empirical study. Before the empirical survey ofairport SMS performance, this research confirmed the SMS imple-mentation plans of TPE (Taoyuan International AirportCorporation (TIAC) 2012), KHH (CAA, 2012a), and TSA (CAA,2012b). The SMS implementation plan is a realistic strategy that

Table 3Analysis of Pearson correlation for airport SMS components.

Components C1 C2 C3 C4

C1 1.0000 0.1292 �0.0216 0.5822– (0.6210) (0.9342) (0.0142)

C2 0.1292 1.0000 0.6088 0.2215(0.6210) – (0.0095) (0.3929)

C3 �0.0216 0.6088 1.0000 0.2952(0.9342) (0.0095) – (0.2499)

C4 0.5822 0.2215 0.2952 1.0000(0.0142) (0.3929) (0.2499) –

78 Y.-H. Chang et al. / Safety Science 75 (2015) 72–86

meets the organization’s approach to managing safety while sup-porting effective and efficient delivery of service (ICAO, 2009a).

To present the practical airport SMS implementation of targetairports, stage two of the survey, the SMS manuals of TPE (TIAC,2012), KHH (CAA, 2012a), and TSA (CAA, 2012b) were sent withthe stage-two questionnaires to 17 experts. These two stages ofexpert questionnaire surveys were completed between September8 and October 30, 2012. The experts who completed them work forthe airline industry, government, and academic institutions; theiraverage working experience was 17 years. To understand theactual operation of an airport SMS and to verify the findings ofresearch at stage two, in this study the top SMS managers at TPE,KHH, and TSA international airports were interviewed betweenMarch 6 and 8, 2013. The average working experience of each ofthe top SMS managers interviewed was more than 20 years.

4.1. The weight of the airport SMS

The first-stage expert questionnaire focused on two parts:determining the interactive network of the airport SMS compo-nents, and, using the ANP method, obtaining the weights of com-ponents and elements.

The results of stage one were processed using the ANP steps(Azimi et al., 2011). At this stage, the construction of a networkdependency of the airport SMS components was based on review-ing the SMS manual, interviews with experts, Pearson correlationcoefficient analyses (Hsu, 2009), and Spearman rank coefficientanalyses. Depending upon the real operations of each SMS compo-nent, this study defined the inner loops by the nature of the feed-back of SMS elements. For example, elements e21 and e24 arefeedback to component C2, which indicates that component C2

has an inner loop (Fig. 3). The result of the Pearson correlationcoefficient analysis shows that all components were positively cor-related, except for the insignificant relationship between C1 and C3.The most significant correlation was between C2 and C3

C1: Safety policy and objectives

e11 Management commitment and responsibilitye12 Safety accountabilitye13 Appointment of key safety personnele14 Coordination of emergency response planninge15 SMS documentation

C2: Safety risk management

e21 Hazard identificatione22 Safety risk assessment systeme23 Safety risk mitigation strategiese24 To implement, track and monitor the safety risk mitigation

Goal: Airport SMS Performanc

Airport SMS Performance Ev

Fig. 3. The dependency network of the a

(p = 0.0095) and the next was between C1 and C4 (p = 0.0142)(see Table 3).

Based on the results in step one, this study combined the rela-tionships of components, and developed the dependency networkof the airport SMS (Fig. 3). According to the output of the relativeweight matrix using super decision software, there were threecomponents (C2, C3, and C4) that provided the feedback for theinner dependency network, and there were five interrelations forthe airport SMS components: C1 and C2, C1 and C4, C2 and C3, C2

and C4, and C3 and C4.This study used geometric means (Saaty, 1980) to deal with the

responses of the experts from step 1 to step 4. Because the superm-atrix (Table 4) covers the whole network (Fig. 3), the columns inthe limited supermatrix represent the final priority. Based on theaverage of all the responses of the experts under a component oran element, the result can be or may be over-exaggerated by valuesmuch larger than those of the geometric mean. Consequently, theresults based on the average in the pairwise comparison may beoverestimations. However, the overall ranks for components areunchanged; only the elements under the components haveminor changes in rank. The weighted rankings of the airport SMScomponents from high to low are: Safety risk management (C2)

C4: Safety promotion

e41 Safety culturee42 Training and educatione43 Safety communicatione44 Safety competency and continuous improvement

C3: Safety assurance

e31 Safety performance monitoring and measuremente32 The management of changee33 A non-punitive safety reporting systeme34 Continuous improvement of the SMS

e Evaluation in Taiwan

aluation in Taiwan

irport Safety Management System.

Table 4The limiting supermatrix for the airport SMS components and elements.

Comp C1 C1 C1 C1 C1 C2 C2 C2 C2 C3 C3 C3 C3 C4 C4 C4 C4

Comp Elem e11 e12 e13 e14 e15 e21 e22 e23 e24 e31 e32 e33 e34 e41 e42 e43 e44

C1 e11 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066 0.1066e12 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505 0.0505e13 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540 0.0540e14 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287e15 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287 0.0287

C2 e21 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276 0.1276e22 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638 0.0638e23 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884e24 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884 0.0884

C3 e31 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679e32 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227 0.0227e33 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320 0.0320e34 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255 0.0255

C4 e41 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568e42 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679 0.0679e43 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568 0.0568e44 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339 0.0339

Comp, components; Elem, elements; C, component; e, element.

Y.-H. Chang et al. / Safety Science 75 (2015) 72–86 79

(0.3682), Safety policy and objectives (C1) (0.2685), Safety promotion(C4) (0.2153) and Safety assurance (C3) (0.1480). The top five AirportSMS elements are: Hazard identification (e21) (0.1276), Managementcommitment and responsibility (e11) (0.1066), Safety risk mitigationstrategies (e23) (0.0884), To implement, track, and monitor the safetyrisk mitigation (e24) (0.0884), and Safety performance monitoring andmeasurement (e31) (0.0679). The details of overall weighted rank-ings in elements, the rank of elements within a component; therankings of all components are shown in Table 5.

4.2. Evaluating airport SMS performance

In stage 2, linguistic assessments were used to evaluate airportSMS elements using fuzzy numbers, and then the elementswere rated. This study used fuzzy TOPSIS (Chen, 2000) to evaluate

Table 5The rankings of weights for airport SMS components and elements.

Component Elements Lim(Ge

C1: Safety policy andobjectives

e11 Management commitment and responsibility 0.1

e12 Safety accountability 0.0e13 Appointment of key safety personnel 0.0e14 Coordination of emergency response planning 0.0e15 SMS documentation 0.0

C2: Safety riskmanagement

e21 Hazard identification 0.1

e22 Safety risk assessment system 0.0e23 Safety risk mitigation strategies 0.0e24 To implement, track and monitor the safety riskmitigation

0.0

C3: Safety assurance e31 Safety performance monitoring andmeasurement

0.0

e32 The management of change 0.0e33 A non-punitive safety reporting system 0.0e34 Continuous improvement of the SMS 0.0

C4: Safety promotion e41 Safety culture 0.0e42 Training and education 0.0e43 Safety communication 0.0e44 Safety competency and continuousimprovement

0.0

* Geometric mean.

the SMS performances of TPE, KHH, and TSA international airports.We used CGD (Yager, 1980) to defuzzify and then to identify thebest and the worst values to obtain the FPIS and FNIS fuzzy sets.The distances of FPIS (d�i ) and FNIS (d�i ) are shown in Table 6.

Eq. (10) was used to obtain the CC value by calculating the sumof the FPIS (d�i ) and FNIS (d�i ) distances (Table 6). The CC value tellsthe distance of the SMS performance from the FPIS or FNIS: if theCC value is high, the distance is close to the FPIS and the perfor-mance is good, and vice versa. In this study, the overall rankingof the SMS elements performance evaluation by CC value wasTPE, KHH, and TSA (Table 7). The government and academic assess-ments were the same in the order: TPE, KHH, and TSA. The airlineindustry ranked the three airports differently (in descendingorder): TSA, TPE, and KHH (Table 8).

itingo*)

OverallRanking

Rank withincomponents

Totalweight

Rank ofcomponents

066 2 1 0.2685 2

505 11 3540 10 2287 14 4287 14 4

276 1 1 0.3682 1

638 7 4884 3 2884 3 2

679 5 1 0.1480 4

227 17 4320 13 2255 16 3

568 8 2 0.2153 3679 6 1568 8 2339 12 4

Table 7Overall assessment of the ranking of airport SMS elements performance evaluation.

Airport TPE KHH TSA

CC 0.7082 0.3810 0.2954Rank 1 2 3

TPE, Taoyuan International Airport; TSA, Songshan International Airport; KHH,Kaohsiung International Airport; CC, closeness coefficient.

Table 6The distances of airport SMS elements from FPIS and FNIS.

dð~v ij; ~v�j Þa Airports (by FPIS) dð~v ij; ~v�j Þ

a Airports (by FNIS)

Elements TPE TSA KHH Elements TPE TSA KHH

e11 0.0000 0.0409 0.0416 e11 0.0416 0.0073 0.0000e12 0.0450 0.0515 0.0000 e12 0.0103 0.0000 0.0515e13 0.0037 0.0000 0.0037 e13 0.0000 0.0037 0.0000e14 0.0000 0.0125 0.0125 e14 0.0125 0.0000 0.0000e15 0.0000 0.0274 0.0274 e15 0.0274 0.0000 0.0000e21 0.0287 0.0000 0.0150 e21 0.0000 0.0287 0.0346e22 0.0150 0.0150 0.0000 e22 0.0000 0.0000 0.0150e23 0.0000 0.0226 0.0226 e23 0.0226 0.0000 0.0000e24 0.0000 0.0104 0.0000 e24 0.0104 0.0000 0.0104e31 0.0000 0.0080 0.0354 e31 0.0354 0.0276 0.0000e32 0.0117 0.0000 0.0107 e32 0.0016 0.0107 0.0000e33 0.0201 0.0000 0.0150 e33 0.0000 0.0201 0.0053e34 0.0000 0.0017 0.0184 e34 0.0184 0.0191 0.0000e41 0.0000 0.0267 0.0601 e41 0.0601 0.0334 0.0000e42 0.0000 0.0190 0.0190 e42 0.0190 0.0000 0.0000e43 0.0000 0.0225 0.0094 e43 0.0225 0.0000 0.0134e44 0.0000 0.0074 0.0199 e44 0.0199 0.0127 0.0000

d�ib 0.1242 0.2655 0.3107 d�i

b 0.3015 0.1635 0.1303

FPIS, fuzzy positive ideal solution; FNIS, fuzzy negative ideal solution; TPE, TaoyuanInternational Airport; TSA, Songshan International Airport; KHH, Kaohsiung Inter-national Airport.

a dð~v ij; ~v�j Þ is the distance between airport fuzzy set and FPIS, and dð~v ij; ~v�j Þ is thedistance between airport fuzzy set and FNIS.

b d�i is the sum of distance for dð~v ij; ~v�j Þ, and d�i is the sum of distance fordð~v ij; ~v�j Þ.

Table 9The specific ranking of airport SMS components.

Components/CC value rank TPE KHH TSA

C1: Safety policy and objectives 0.9873 0.9417 0.9576Rank 1 3 2C2: Safety risk management 0.4293 0.3749 0.6155Rank 2 3 1C3: Safety assurance 0.6056 1.0000 0.5377Rank 2 1 3C4: Safety promotion 1.0000 0.3287 0.1572Rank 1 2 3

TPE, Taoyuan International Airport; TSA, Songshan International Airport; KHH,Kaohsiung International Airport; CC, closeness coefficient.

80 Y.-H. Chang et al. / Safety Science 75 (2015) 72–86

For component 1, TPE was first with a CC value of 0.9873; forcomponent 2, TSA was first with a CC value of 0.6155; for compo-nent 3, KHH was first with a CC value of 1.0000; and for component4, TPE was first with a CC value of 1.0000 (Table 9).

4.3. Interviews with experts and summary

To understand the actual operations of the airport SMS, and toverify the results of this research, three top SMS managers, eachwith more than 20 years of working experience at TPE, KHH, orTSA international airport, were interviewed in March 2013. Basedon the specific SMS components, the interviews and discussionsare summarized below.

C1: Safety policy and objectives (Overall ranking: TPE, TSA, andKHH)

Table 8Group assessment of the ranking of airport SMS elements performance.

Group Airline industry Governments a

Airport TPE KHH TSA TPE

CC 0.4128 0.4071 0.6481 0.6863Rank 2 3 1 1

TPE, Taoyuan International Airport; TSA, Songshan International Airport; KHH, Kaohsiun

Safety policy provides the foundation for SMS (FAA, 2012).Stolzer et al. (2008) pointed out that senior managers by devotingattention, time, and resources to SMS, are important for ensuringthat SMS is efficiently implemented. TPE is the top-ranked airportexcept for C1 (Safety policy and objectives) and e13 (Appointment ofkey safety personnel) (Tables 5 and 6). It means that the perfor-mance of e13 is closely related to the nature of government-ownedincorporated airports (TPE) and governmental and civil-militaryairports (KHH and TSA). The flight operations division staff mem-bers of all three airports were trained in SMS at the Taiwan CAA’sAviation Training Institute, and the seed training for the KHH andTPE for the SMS course is regularly held at the Singapore AviationAcademy. KHH ranked first for element e13, and TPE and TSA bothranked second. This result agrees with the actual performanceevaluation of e13 by the experts.

C2: Safety risk management (Overall ranking: TSA, TPE, and KHH)

The ICAO stated (2009) that ‘‘airport safety administrators shallbe appointed based on a combination of reactive, proactive, andpredictive methods of safety data collection in identifying areasof hazard’’. In the present study, we found that all three airportsfollowed the ICAO’s suggestions about conducting risk manage-ment evaluations, not only because it is written in the SMS manual,but also because it is necessary in regular daily operations. Ourresearch for part two showed that when an airport’s surface andterminal areas (such as runway repairs or terminal construction)are under construction, more risk management is needed.

Based on the interviews, we learned that the TPE Fight Opera-tions Division and Air Traffic Control (ATC) Department will con-duct runway inspections (ICAO, 1983) twice a day during off-peak hours during the runway-repair period from June 2013 toFebruary 2014. It is known that the damage to TPE’s runways isrelated to its SMS risk-management performance, its service qual-ity, and the interaction of its stakeholders. Moreover, TPE’s Opera-tions Control Center (OCC) integrates the information of airsideand landside to the related divisions to quickly respond withappropriate movement announcements.

TSA is ranked first in C2 performance, which indicates a quickresponse to the requirements of airport users, as well as stable run-

rea Academic area

KHH TSA TPE KHH TSA

0.6357 0.2672 0.8723 0.3112 0.10622 3 1 2 3

g International Airport; CC, closeness coefficient.

Y.-H. Chang et al. / Safety Science 75 (2015) 72–86 81

way surfaces without construction. The KHH SMS group hassmoothly embedded the safety concepts into its daily work byholding regular airport SMS committee, pilot, runway safety, andapron safety meetings.

C3: Safety assurance (Overall ranking: KHH, TPE, and TSA)

For component C3, an airport SMS staff ‘‘shall practice the man-agement of change (e32)’’ (ICAO, 2009b) ‘‘and A non-punitive safetyreporting system (e33)’’ (FAA, 2007). KHH is ranked first for thiscomponent. KHH’s SMS practice is ‘‘Local Culture-based’’ (e.g., per-sonally reminding each other about safety and being concernedabout all stakeholders in the airport); all the stakeholders arerespected and assisted (e.g., at the many meetings with pilotsevery quarter).

TPE’s SMS practice is ‘‘The participation of flight safety and secu-rity for all citizens’’; all stakeholders are the best monitors to watchany risk and to track the movement of improvement. In particular,with respect to human factor management, TPE uses the safetyrecords of employees to control the approval of their workinglicenses; TSA uses the same methods to reduce events caused byhuman factors. In the external and internal safety audits, TPE andKHH follow the airport SMS operations manual, and TSA practicesthe CAA’s inspection operations. Based on the airport SMS imple-mentation for C3, the results are consistent with the overall ranking.

C4: Safety promotion (Overall ranking: TPE, KHH, and TSA)

An organization should continually promote safety as a corevalue with practice, safety education, and safety culture (Stolzeret al., 2008). For this reason, the results of performance evaluationsreflect an airport’s sustainable operations, particularly in safetyeducation for seed-instructor training: TPE and KHH participatein a routine training program for seed instructors held at Singa-pore’s Aviation Academy. All flight operations related to new per-sonnel have an SMS course at the CAA’s Aviation TrainingInstitute. TSA creates safety risk notifications for the surface dri-ver’s license exam, which not only provide instant SMS notificationchannels, but also encourage all stakeholders to inform the TSAsafety office and flight operations center of safety risks.

For component C4, airport safety culture is the core value forsafety improvement. TPE emphasizes the responsibility of all citi-zens for safety; KHH smoothly and efficiently executes daily dutieswith a local safety culture; and TSA’s safety culture is to respond toits users’ needs in a fast and timely manner.

The overall ranking on Airport SMS performance evaluation is:TPE, KHH, and TSA. The SMS manuals at the three airports have beencompleted; TPE’s and KHH’s SMS teams follow the directions of theICAO SMS manual. The C3 and C4 operations have not yet been imple-mented at TSA, particularly under the e31 (Safety performance moni-toring and measurement) requirements. TSA uses the Taiwan CAA’sairport auditing system to replace external auditing and self-audit-ing. Based on the results of the overall ranking, the content of theinterviews confirm the actual practices of the three airports.

Moreover, TSA is both a civil and a military airport, whichmeans that it has different surface management systems for theTaiwan CAA and the military; for example, the A, B, and C gapsfor a military taxiway are different from those of a civil taxiway.However, considering the overall SMS performance from the avia-tion industry’s viewpoint, TSA ranks first because it emphasizes theinteraction between stakeholders and the airport SMS group. Thisis because TSA’s SMS group emphasizes quick assistance to usersin its safety culture.

Finally, the overall performance ranking for the three airports isconsistent with the actual relationship between C2, C3, and C4. In

reference to TSA’s being third in the overall ranking, even thoughit responds quickly to users and its risk management operationsare efficient, its implementation of C3 and C4 operations affectsits airport SMS performance ranking. Based on the different nat-ures of government-owned incorporated and governmental andcivil-military airports, a modern airport must efficiently respondto the dynamic requirements when an airport’s surface and termi-nal areas are under construction, and the different properties of anairport can affect the implementation of safety policy and safetyculture. For example, in TPE’s SMS performance of C2, the moreongoing that surface construction is, the more risk managementis needed, not only in the human factor management system, butalso in airport facilities to prevent foreign object damage (FOD)caused by an object-littered surface under construction.

5. Conclusions and suggestions

Airport safety management is important for the aviation indus-try. This research intended to establish airport SMS componentsand elements to evaluate international airport SMS performanceby reviewing the SMS manuals of the ICAO, Taiwan CAA, and U.S.FAA. The results of this research are based on a questionnaire sur-vey and interviews with experts. In the first stage, the airport SMSweights and weighted rankings for components and elements weredetermined using the ANP. The rankings of components from highto low were: C2 (Safety risk management), C1 (Safety policy andobjectives), C4 (Safety promotion), and C3 (Safety assurance), andthe top four elements were e21 (Hazard identification), e11 (Manage-ment commitment and responsibility), e23 (Safety risk mitigationstrategies), and e24 (To implement, track and monitor the safety riskmitigation).

Because the weighted rankings of individual SMS componentsin stage one were different, it was necessary to compare the SMSperformance of these three airports in stage two using fuzzy TOP-SIS. We found that, under component C1, the overall performanceranking (in descending order) was TPE, TSA, and KHH; under C2,it was TSA, TPE, and KHH; under C3, it was KHH, TPE, and TSA;and under C4, it was TPE, KHH, and TSA.

The overall SMS performance ranking of the three internationalairports was TPE, KHH, and TSA, by both the weighted-average andthe fuzzy TOPSIS methods. Using the grouping view under the Gov-ernment and Academic Expert areas, the ranking was identical.However, from the airline industry’s viewpoint, the ranking wasTSA, TPE, and KHH. To verify the results obtained from the stage-two questionnaire survey, we also conducted face-to-face inter-views with the top SMS managers at these airports after thestage-two survey. The major findings from these interviews aresummarized below.

Under C1, the performance ranking was TPE, TSA, and KHH.Based on the nature both of government-owned and of civil-mili-tary and governmental airports, modern airports must efficientlyrespond to the requirements of the stakeholders. In addition, dif-ferent airport properties can affect the implementation of safetypolicy and safety culture. Under C2, the more frequently construc-tion of the surface and terminal areas occurs, the more attention isneeded for risk management under the dynamic and uncertain sit-uations in airport SMS operations. We found that the C2, C3, and C4

components are related.Under C3, the overall performance ranking was KHH, TPE, and

TSA. This is the result of actual practice in external- and self-audit-ing of SMS operations at TPE and KHH, while TSA uses the TaiwanCAA’s airport auditing, which results in a different SMS safety pro-motion aspect. To sustain airport operations, it is necessary to pro-mote safety education. Under C4, the performance ranking was TPE,

82 Y.-H. Chang et al. / Safety Science 75 (2015) 72–86

KHH, and TSA, because TPE and KHH participate in regular interna-tional training programs for seed instructors to improve airportsafety management capability.

Based on the findings of this research, we suggest the following:(1) establish the airport SMS performance evaluation system bygovernment administration and share safety management experi-ences from top-ranked airports; (2) share the safety informationusing the Taiwan CAA’s safety events database, and conduct safetyconferences for airport SMS staff, airlines industry managers, andacademics; (3) improve the efficiency of airport SMS, evaluationscales, and report writing by implementing component C2 (Safetyrisk management), which can contrast with the ICAO Annex 13: Air-craft accident and incident investigation (ICAO, 2001a) and Doc9859: Safety Management Manual.

To support more quantitative information in the findings of thisresearch, future research should focus on safety events, the analy-sis of the root causes of airport surface maintenance, and statisticalanalyses of airport safety event data to help improve safety quality.The findings of this research can provide aviation authorities, air-port administrators, and airline companies in Taiwan with a direc-tion for safety risk management and for the allocation of materialsand resources to conduct safety training in order to preventunwanted aviation events from occurring.

This study incorporated the unified ICAO and Taiwan CAA reg-ulations to develop airport SMS components and elements.Because the scales of international airports are different, sharing

� Safety riskassessment and

safety data between airports is informative for the aviation indus-try, government, and academic experts to prevent accidents fromoccurring. In addition, safety data standardization is helpful forexchanging international safety information. As is well known,Safety risk management is the heart of an airport SMS; therefore,the standardization made using ICAO regulations and the EuropeanCoordination Centre for Accident and Incident Reporting Systems(ECCAIRS) is necessary, and Safety assurance is the feedback forall systems because safety information can always be updated. Fur-thermore, Safety promotion is not only for the airport SMS system,but also for the airport SMS stakeholders, which include the airlineindustry, passengers, and airport personnel; thus, the Safety policyand objectives of the airport SMS system can be followed andupdated using data from the inner and outer stakeholders.

Acknowledgments

The authors are grateful to the referees and an associate editorfor their constructive comments and suggestions on the originalmanuscript so that the paper is more readable and valuable. Thefirst author’s research was supported by MOST-103-2410-H-006-053-MY3, Taiwan, the second author’s research by NSC-101-2410-H-006-010-MY2, Taiwan, and the third author’s research byNSC-101-2118-M-006-004, Taiwan and the Department of Statis-tics, The University of Georgia, USA.

Appendix A. Airport SMS components and elements for requirements

ICAO Annex14 (2009b)

UK CAA CAP 168(UK CAA, 2011)

Australia CASA AC139-016 (CASA, 2005)

U.S. FAA AC 150/5200-37 (FAA,2007)

� Safetytraining andeducation

Canada TCCAAC 300-002 (TCCA, 2009)

1. Safety policy andobjectives

1. Safety policy andobjectives

AN EIGHT-STEP PROCESS AS IT RELATES TO

THE OPERATION OF AN AERODROME

1. Safety policyand objectives

1. Safety managementplan

� Managementcommitment andresponsibility

� Managementcommitment andresponsibility

1. Policy

� Safety policy � Safety policy

� Roles, responsibilities

� Safetyaccountabilities

� Safetyaccountability

2. Management accountability

� Safetyobjectives

� Non-punitivereporting policy

� Appointment of keysafety personnel

� Appointment of keysafety personnel

3. Establishing a process tomanage risks

2. Safety risk

management

and employeeinvolvement� Communication

objectives, and goals

� Coordination ofemergencyresponse planning

� Performance

� Coordination ofemergencyresponse planning� SMS documentation

4. Setting up a reporting systemto record hazards, risks andactions taken

3. Safetyassurance

� Safety planning,

� SMS documentation

2. Safety risk

5. Training and educating staff

4. Safetypromotion

measurement� Management review

2. Safety riskmanagement

management

6. Auditing the operation andinvestigating incidents andaccidents

� Safetypromotion

2. Document management� Identification and

� Hazardidentification

� Hazardidentification

7. Setting up a system to controldocumentation and data

maintenance of

� Safety riskassessment andmitigation

mitigation

3. Safety assurance� Safety performance

8. Evaluating how the system isoperating

3. Safety assurance

applicable regulations

� SMS documentation

� Safety performancemonitoring andmeasurement

monitoring andmeasurement� Management of

change

� Management ofchange

� Continuousimprovement of the

� Records management

� Continuousimprovement of theSMS

SMS

3. Safety oversight� Reactive processes� Proactive processes� Investigation and

analysis� Risk management

Y.-H. Chang et al. / Safety Science 75 (2015) 72–86 83

Airport SMS components and elements for requirements (continued)

ICAO Annex14 (2009b)

C1 Safety policy and

UK CAA CAP 168(UK CAA, 2011)

Australia CASA AC139-016 (CASA, 2005)

U.S. FAA AC 150/5200-37 (FAA,2007)

Canada TCCAAC 300-002 (TCCA, 2009)

4. Safety promotion

4. Safety promotion � Training and

education

� Training and

education

� Training, awareness

� Safetycommunication

� Safetycommunication

and competence5. Quality assurance

4. Training

� Quality assurance

6. Emergency

preparedness

� Emergency

preparedness andresponse

Appendix B. The definitions of airport SMS components and elements

Components

Elements Definition

e11 Management commitment andresponsibility (ICAO, 2009b)

1. Safety policy shall be in accordance with international andnational requirements, and shall be signed by the accountableexecutive of the organization

2. The safety policy shall reflect organizational commitmentsregarding safety; shall include a clear statement about theprovision of the necessary resources for the implementation of thesafety policy

3. The safety policy shall include the safety reporting procedures;shall clearly indicate which types of operational behaviors areunacceptable; and shall include the conditions under whichdisciplinary action would not apply

4. The safety policy shall be periodically reviewed to ensure itremains relevant and appropriate to the organization

objectives (ICAO,

2009b)

e12 Safety accountabilities (ICAO,2009b)

1. The certified airport shall identify the accountable executive who,irrespective of other functions, shall have ultimate responsibilityand accountability, on behalf of the certified aerodrome, for theimplementation and maintenance of the SMS

2. The certified airport shall also identify the accountabilities of allmembers of management, irrespective of other functions, as wellas of employees, with respect to the safety performance of the SMS

e13 Appointment of key safetypersonnel (ICAO, 2009b)

1. The certified airport shall identify a safety manager to be theresponsible individual and focal point for the implementation andmaintenance of an effective SMS

e14 Coordination of emergencyresponse planning (ICAO, 2009b)

1. The certified aerodrome shall ensure that an emergency responseplan that provides for the orderly and efficient transition fromnormal to emergency and the return to normal operations

2. The certified aerodrome is properly coordinated with theemergency response plans of those organizations it must interfacewith during the provision of its services

e SMS documentation (ICAO, 2009b) 1. The organization shall develop and maintain SMS documentation

15

describing(1) The safety policy and objectives(2) The SMS requirements, the SMS processes and procedures, and(3) The accountabilities, responsibilities and authorities for

processes and procedures, and the SMS outputs2. The certified aerodrome shall develop and maintain a Safety

Management Systems manual (SMSM), to communicate itsapproach to the management of safety throughout theorganization

(continued on next page)

84 Y.-H. Chang et al. / Safety Science 75 (2015) 72–86

The definitions of airport SMS components and elements (continued)

Components

Elements Definition

C2 Safety riskmanagement (ICAO,2009b)

e21 Hazard identification (FAA, 2007)

1. Hazard identification shall be based on a combination of reactive,proactive and predictive methods of safety data collection

2. The hazard identification stage considers all the possible sourcesof system failure which should include:(1) The equipment (example: construction equipment on a

movement surface)(2) Operating environment (example: cold, night, low visibility)(3) Human element (example: shift work)(4) Operational procedures (example: staffing levels), and(5) Maintenance procedures (example: nightly movement area

inspections by airport electricians)(6) External services (example: ramp traffic by Fixed-Base

Operator (FBO) or law enforcement vehicles)

e22 Safety risk assessment system(FAA, 2007)

1. The airport operator shall estimate the level of risk such as byusing the predictive risk matrix (see Fig. 3). Risk is the compositeof the predicted severity and likelihood of the outcome or effect(harm) of the hazard in the worst credible system state

e Safety risk mitigation strategies THE RISK LEVELS USED IN THE PREDICTIVE RISK MATRIX CAN BE DEFINED AS:

23

(FAA, 2007)

1. High risk – unacceptable level of risk: The proposal cannot beimplemented or the activity continued unless hazards are furthermitigated so that risk is reduced to medium or low level

2. Medium risk – acceptable level of risk: Minimum acceptablesafety objective; the proposal may be implemented or the activitycan continue, but tracking and management are required

3. Low risk – acceptable without restriction or limitation

e24 To implement, track and monitorthe safety risk mitigation (FAA, 2007)

1. High risk – tracking and management involvement are required,and management must approve any proposed mitigating controls.Catastrophic hazards that are caused by:(1) Single-point events or failures(2) Common-cause events or failures, and(3) Undetectable latent events in combination with single point or

common cause events are considered high risk, even ifextremely remote

2. Medium risk – acceptable level of risk: the proposal may beimplemented or the activity can continue, but tracking andmanagement are required

3. Low risk – the identified hazards are not required to be activelymanaged, but are documented

C3 Safety assurance(ICAO, 2009b)

e31 Safety performance monitoringand measurement (FAA, 2007)

1. Safety assurance includes self-auditing, external auditing, andsafety oversight. Safety oversight can be achieved throughauditing and surveillance practices, given the diverse activities atcommercial airports

e32 The management of change (ICAO,2009b)

1. The certified aerodrome shall develop and maintain a formalprocess to identify changes within the organization which mayaffect established processes and services; to describe thearrangements to ensure safety performance before implementingchanges; and to eliminate or modify safety risk controls that areno longer needed or effective due to changes in the operationalenvironment

e33 A non-punitive safety reportingsystem (FAA, 2007)

1. The SMS should include a visible non-punitive safety reportingsystem supported by management

2. The safety reporting system should permit feedback frompersonnel regarding hazards and safety-related concerns

3. The SMS should use this information to identify and address safetydeficiencies. The safety reporting system may also identify andcorrect non-conformance to safety policy

Y.-H. Chang et al. / Safety Science 75 (2015) 72–86 85

The definitions of airport SMS components and elements (continued)

Components

Elements Definition

e Continuous improvement of the 1. The certified aerodrome shall develop and maintain a formal

34

SMS (ICAO, 2009b)

process to identify the causes of substandard performance of theSMS, determine the implications of substandard performance of theSMS in operations, and eliminate or mitigate such causes

C4 Safety promotion(ICAO, 2009b)

e41 Safety culture (FAA, 2007; TRB,2007)

1. It requires a commitment to safety on the part of seniormanagement. The attitudes, decisions and methods of operationat the policy-making level demonstrate the priority given to safety

2. In effective safety cultures, there are clear reporting lines, clearlydefined duties and well understood procedures

3. Personnel fully understand their responsibilities and know whatto report, to whom and when

4. Senior management reviews not only the financial performance ofthe organization but also its safety performance

e42 Training and education (ICAO,2009b)

1. The certified aerodrome shall develop and maintain a safetytraining programme that ensures that personnel are trained andcompetent to perform the SMS duties. The scope of the safety trainingshall be appropriate to each individual’s involvement in the SMS

e43 Safety communication (FAA, 2007)

1. The certified aerodrome shall develop and maintain formal meansfor safety communication that ensures that all personnel are fullyaware of the SMS, conveys safety-critical information, and explainswhy particular safety actions are taken and why safety proceduresare introduced or changed

2. Systems safety improvement will occur most efficiently if staffand employees are actively encouraged to identify potentialhazards and propose solutions. Some examples of organizationalcommunication are:(1) Safety seminars(2) Safety letters, notices and bulletins(3) Safety lessons-learned(4) Bulletin boards, safety reporting drop boxes, and electronic

reporting through web sites or email(5) A method to exchange safety-related information with other

airport operators through regional offices or professionalorganizations, and

(6) Airport web-based safety reporting system currently beingused by air operators

C4 Safety promotion(ICAO, 2009b)

e44 Safety competency and continuousimprovement (FAA, 2007; TRB, 2007)

1. The safety manager provides current information and trainingrelating to safety issues relevant to the specific operation of theairport. The provision of appropriate training to all staff,regardless of their level in the organization, is an indication ofmanagement’s commitment to an effective SMS. Safety trainingand education should consist of the following:(1) A documented process to identify training requirements(2) A validation process that measures the effectiveness of training(3) Initial (general safety) job-specific training(4) Recurrent safety training(5) Indoctrination/initial training incorporating SMS, and training

that includes human factors and organizational factors

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