Jacek Skorupski

Multi-criteria group decision making under uncertainty with application to air traffic safety

There are many methods for solving problems of multi-criteria group decision making under uncertainty conditions. It is quite often that decision makers cannot formulate unequivocally their individual preference relations between variants. Analysing the causes of a serious aircraft incident is an example where a group of experts is required to have a very detailed yet interdisciplinary knowledge. Obviously, each expert has only a fraction of such knowledge. Hence, experts can make fuzzy evaluations when they are not sure about them or it is not possible to gain full knowledge. There is a need for a method that in such a case takes into account the strength of preference expressed in the significance of each criterion. Both the significance of criteria and the scores assigned to variants can be represented using fuzzy expressions. The proposed method reflects the problems of decision making when both objective (represented using non-fuzzy expressions) and subjective (represented using linguistic expressions) criteria, are involved. The proposed method enables to obtain a solution without having to conduct negotiations between decision makers. This is of advantage when there is a risk that some experts will be dominated by others. The method not only helps define a single preferred solution but also create the preference relation within a group. By applying this method, it is possible to reproduce the actual preference relations of individual decision makers. Presenting them to decision makers may induce them to change their evaluation of the weights of criteria or how they score variants.

A fuzzy system to support the configuration of baggage screening devices at an airport

We model baggage screening devices at an airport to evaluate their effectiveness.Fuzzy inference system to assist airport security manager was built.Evaluation of single X-ray device as well as entire equipment is possible.TIP images number and frequency influence the evaluation of the security system.Devices replacement strategy was evaluated for EPKT airport. An airport is a complex engineering system; it is composed of many elements interconnected with numerous internal relations with a strongly pronounced role of the human factor. One of the specific tasks carried out by the airport managing entity (AME) is to configure the airport security system (ApSS) so that to attain the expected level of confidence in the airport safety and security. This task consists in selection of infrastructure, technical equipment, allocation of personnel and financial means that are necessary to perform all functions of the ApSS. One of the aspects of the configuration of the ApSS is the allocation of available X-ray baggage screening devices searching for items prohibited for transportation. To make this allocation, we need to know how effective these devices are (in terms of detecting prohibited items). This assessment is dependent on several factors which are treated as linguistic variables and are input to fuzzy inference system: the ability to detect explosives, the number of detection lines, the effectiveness of the TIP (Threat Image Projection) system and the age of the machine. Some of these elements are difficult to objective assessment, as they are heavily dependent on the human factor or the information is uncertain or incomplete. So fuzzy ApSS analysis is proposed. The output from the fuzzy inference system is linguistic variable Device evaluation. The meaning of this variable is the ability to protect the aircraft against prohibited items. The proposed new method of assessing the airport baggage screening system involves the construction of a hierarchical fuzzy inference system. The usefulness of the method is exemplified for Katowice-Pyrzowice International Airport, for which an assessment of devices has been performed. The results show that not only allocation of specific devices for specific control points is important for the security of passengers. Also important are the locally accepted principles of their work, which so far are not specified by international regulations. This applies for instance to the selection of the number and frequency of TIP images. Experiments show that the proposed approach can be effective as part of an expert system for supporting the airport operator in configuring ApSS.

Air Traffic Incidents Analysis with the Use of Fuzzy Sets

In safety, reliability as well as risk analysis and management, information often is uncertain and imprecise. The approach to air incident analysis under uncertain and imprecise information presented in our paper is inspired by the possibility theory. Notably, in such analyses these are both: static and dynamic components that have to be included. As part of this work, static analysis of a serious incident has been performed. In order to do this, probability scale which is based on fuzzy set theory has been given. The scenarios of transformation of incident into accident have been found and their fuzzy probabilities have been calculated. Finally, it has been shown that elimination of one of premises for transformation of the incident into accident significantly reduces the possibility of this transformation.

Managing the process of passenger security control at an airport using the fuzzy inference system

A model for assessment of passenger security control efficiency was created.Human factor and the technical factor were taken into account collectively.Hierarchical fuzzy inference system was used and implemented.Passenger security control efficiency was determined in real conditions.Method and software for airport management support was developed. Elements of air transport infrastructure as well as passengers and aircraft are constantly at risk of terrorist attack. One of the most important preventative methods is the security control of persons and baggage at airports. Managing this process requires finding a compromise between high capacity of the terminal and the high effectiveness of the security control. The purpose of this study is to show the applicability of an expert system, which assists security managers in deciding how to organise the security screening process. Due to the important role of the human factor, the need to use experts opinions and the high uncertainty and imprecise nature of information, the developed model and computer tool FUPSCA (FUzzy Passenger Security Control Assessment) uses the fuzzy sets theory and a fuzzy inference system. Its use allows us to adjust the operating parameters of the security screening checkpoint, namely the WTMD sensitivity, number of employees and the frequency of manual controls, to the current level of terrorist threat. As a result of the study it was found that if we want to achieve higher security control effectiveness we should first increase the WTMDs sensitivity and only then increase the frequency of additional manual controls and not the other way round. Of course the FUPSCA system provides specific, quantitative answers. In the future it will be necessary to manage the operation of the passenger security control system using multi-criteria evaluations of: capacity, effectiveness, passenger comfort. FUPSCA will be able to effectively support this process.

Analysis of Air Traffic Incidents using event trees with fuzzy probabilities

This paper presents a methodology for analysing Air Traffic Incidents based on an estimate of the probability of an Air Traffic Incident developing into an Air Traffic Accident (Air Traffic Incidents are officially defined as events which are dangerous but without a catastrophic impact). A new approach is presented as previous research in this area has focused more on defining accident occurrence probabilities. Access to detailed information on Air Traffic Incidents is limited and for this reason the methodology developed was based on Fuzzy Set Theory. Analysis was carried out using Event Trees leading from a real Incident to a hypothetical Accident with the probabilities of occurrence of the various scenarios being defined by fuzzy sets. The results of this analysis enable the calculation of the fuzzy probability of the Incident being transformed into an Accident. Performing this analysis, new measuring techniques for the comparison of fuzzy sets were developed and partially verified. The Case Study presented in the paper analyses a Serious Runway Incursion Incident. This Serious Incident is analysed for influencing factors such as: pilot and flight controller skill levels, airport traffic volume, weather conditions, airport procedures and airport geometry. Applying the methods presented in this paper enables an assessment of the effectiveness of Preventive Recommendations of Accident/Incident Investigation Commissions. Additionally, probability estimations can be developed for different incident situations allowing the identification of Security System Weak Points thus enabling appropriate proactive measures to be taken for their elimination. Fuzzy probability of a serious air traffic incident developing into an accident.New measures for comparing fuzzy sets and their properties.Events importance and sensitivity analysis of the incident.Analysis of the State Commission for Aircraft Accident Investigation recommendation.

Telematic Support of Baggage Security Control at the Airport

A key element of baggage security control at the airport is a human - the security screener. He/she performs some of the tasks remotely, and is supported by the telematic system, making the x-ray baggage screening. The aim of this paper was to analyze the dependence of the number of errors on the experience and the frequency of virtual threat images projection (TIP). The study was based on measurements under real conditions at the Katowice-Pyrzowice International Airport. In the framework of this research two basic types of errors made by security screeners were identified. The results show that the number of errors is dependent from both the experience and the frequency of the stimulus, represented by TIP images. As a result, it was possible to determine the boundary level of experience that entitles security screener to independent work. Also the recommended frequency of threat images projections was determined.

Airport Traffic Simulation Using Petri Nets

Airport traffic consists of aircraft performing landing, takeoff and taxi procedures. It is controlled by air traffic controller (ATC). To safely perform this task he/she uses traffic surveillance equipment and voice communication systems to issue control clearances. One of the most important indicators of this process efficiency is practical airport capacity, which refers to the number of aircraft handled and delays which occurred at the same time. This paper presents the concept of airport traffic modelling using coloured, timed, stochastic Petri nets. By the example of the airport with one runway and simultaneous takeoff and landing operations, the applicability of such models in analysis of air traffic processes is shown. Simulation experiments, in which CPN Tools package was used, showed the impact of the initial formation of landing aircraft stream on airside capacity of the airport. They also showed the possibility of its increase by changes in the organisation of takeoff and landing processes.

Methods of air traffic management in the airport area including the environmental factor

ABSTRACT In the modern approach to air traffic management (ATM), issues related to air quality and climate protection have led to the introduction of a growing number of new restrictions instead of having these issues be the objectives of actions taken. The aim of the study was to investigate whether it is possible to improve air quality while controlling pollution emission by introducing changes in the organization of air traffic control at the airport. For this purpose, mathematical models of emissions were created. These concern the movement of aircraft near the airport and emission of carbon dioxide and the spread of human health related substances emitted from a landing airplanes engine. The first case refers to the possibility of using different arrival procedures. The second case was to adapt the Pasquill formula by treating landing aircraft as a sequence of point-source emissions. As a result of applying the designed models and software tools, it was proven that both a change in the arrival trajectory and a change of the runway can contribute to a reduction of CO2 emission into the atmosphere. The emission maps created for different aircraft approach profiles show the ability to control the local concentration of harmful emissions. The study clearly shows that the current approach of maximizing throughput is not beneficial to air quality. ATM services should consider the use of other variants of air traffic organization, particularly during periods of reduced traffic.

Model of the Hierarchical Process of Managing the Approaching Air Traffic in the Terminal Area

Air traffic in the airport controlled area is carried out according to standard procedures. However, they are disturbed by random factors, so the traffic is stochastic in nature and requires ongoing monitoring by the air traffic controller that operates in the approach control sector (TMA). One of his/her goals is to form the landing aircraft queue so as to maximize the airport capacity. The task is difficult because there are multiple entry points to the TMA and many points at which the individual aircraft streams merge. The paper presents the model of the process of forming landing aircraft queue. The model has been implemented as a coloured Petri net. It has a hierarchical structure corresponding to the actual multi-level structure of the merging aircraft streams process. The study shows an example of modelling of the approaching air traffic consisting of aircraft landing at the Warsaw Chopin airport on the RWY 11 runway. The developed software system SECRAN can be used to support the approach controller in the planning process and in the current control of approaching air traffic in TMA area.

A fuzzy model for evaluating metal detection equipment at airport security screening checkpoints

Every passenger who travels by air is exposed to security screening. As part of this procedure, the passenger typically is screened by a walk-through metal detector. Such a device should effectively detect prohibited metal items while simultaneously ensuring adequate throughput at the security screening checkpoint. Therefore, it is necessary to evaluate both these factors when selecting an appropriate walk-through metal detector and its parameters. However, while it is easy to measure passenger throughput, it is much more difficult to determine the effectiveness of a detector, which is a subjective concept.This paper presents a quantitative method for evaluating the effectiveness of walk-through metal detectors. Since the evaluation is subjective and based on incomplete and imprecise input information, a fuzzy inference method is used, where the input values are expressed as linguistic variables. The research presented in this paper involved field measurements of the sensitivity of walk-through metal detectors and a survey of experts in order to correctly determine the detector sensitivity values. The model for evaluating walk-through metal detectors is implemented in FUGAS (Fuzzy Gate Assessment System), which was tested at the Katowice-Pyrzowice Airport in Poland. The experimental results demonstrate that a fuzzy inference system can be very effective at assisting airport managers in selecting and configuring the equipment used at airport security screening checkpoints.