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Ouranos I.,Hellenic Civil Aviation Authority | Ouranos I.,Technological Educational Institute of Crete | Ogata K.,Japan Advanced Institute of Science and Technology | Stefaneas P.,National and Kapodistrian University of Athens
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

The Timed Observational Transition System (TOTS)/CafeOBJ method is a version of the OTS/CafeOBJ method for modeling, specification and verification of distributed systems and protocols with real time constraints. In this paper we report on a case study from the field of source authentication protocols, TESLA protocol, to show the application of the method to such complex systems. We prove that our model of the protocol satisfies that the receiver does not accept as authentic any message unless it was actually sent by the sender. To verify the property we have used several other invariants which include timing information. To our knowledge, this is the first time that the method has been applied to the formal analysis of such a complex protocol. © 2012 Springer-Verlag. Source


Ouranos I.,Hellenic Civil Aviation Authority | Stefaneas P.,National Technical University of Athens
Studies in Computational Intelligence | Year: 2014

We sketch some first steps towards the definition of a protocol algebra based on the framework of behavioural algebraic specification. Following the tradition of representing protocols as state machines, we use the notion of Observational Transition System to express them in an executable algebraic specification language such as CafeOBJ. This abstract approach allows defining several useful operators for protocol reasoning and proving properties of them using theorem proving techniques and CafeOBJ term rewriting machine. The proposed protocol algebra is inspired by the module algebra and the hierarchical object composition technique. © 2014 Springer International Publishing Switzerland. Source


Malakis S.,Hellenic Civil Aviation Authority | Kontogiannis T.,Technical University of Crete
International Journal of Aviation Psychology | Year: 2012

An observational field study was carried out to examine the degree that refresher training in air traffic control can account for the demands of real-world emergencies. The refresher-training exercises of 21 teams of en route controllers were observed and a number of real incidents were analyzed at a major European Area Control Centre. Expert controllers were observed handling 53 simulated emergencies and abnormal situations during their annual refresher training and their companion team resource management course. The training curriculum was found to be technically oriented. Responding to emergencies was practiced in scenarios less representative of real situations where the controllers do their job in the context of many interruptions, flight crew deviations, and unrecovered errors. Results indicated a substantial gap between formal training requirements and operational demands. An advanced safety training course is proposed on the basis of cognitive task analysis to increase the cognitive fidelity of simulations and focus on cultivating taskwork and teamwork skills. © 2012 Copyright Taylor and Francis Group, LLC. Source


Kontogiannis T.,Technical University of Crete | Malakis S.,Hellenic Civil Aviation Authority
Accident Analysis and Prevention | Year: 2012

A recursive model of accident investigation is proposed by exploiting earlier work in systems thinking. Safety analysts can understand better the underlying causes of decision or action flaws by probing into the patterns of breakdown in the organization of safety. For this deeper analysis, a cybernetic model of organizational factors and a control model of human processes have been integrated in this article (i.e.; the viable system model and the extended control model). The joint VSM-ECOM framework has been applied to a case study to help safety practitioners with the analysis of patterns of breakdown with regard to how operators and organizations manage goal conflicts, monitor work progress, recognize weak signals, align goals across teams, and adapt plans on the fly. The recursive accident representation brings together several organizational issues (e.g.; the dilemma of autonomy versus compliance, or the interaction between structure and strategy) and addresses how operators adapt to challenges in their environment by adjusting their modes of functioning and recovery. Finally, it facilitates the transfer of knowledge from diverse incidents and near misses within similar domains of practice. © 2012 Elsevier Ltd. All rights reserved. Source


Kontogiannis T.,Technical University of Crete | Malakis S.,Hellenic Civil Aviation Authority
Cognition, Technology and Work | Year: 2013

The continued growth of civil aviation and the introduction of new air traffic management systems have increased the complexity of the system, hence requiring more adaptable patterns of control and coordination. There is a need to look deeper into the patterns of control, the transfer of control and coordination across boundaries or sectors and the adaptation to unexpected scenarios that may contribute to 'loss of control' events. To this end, this article elaborates on the extended control model (Hollnagel and Woods 2005) and complements a functional description of the air traffic control (ATC) system with several strategies required in 'being in control' of the joint cognitive system. Reviews of the literature, field studies and observations of performance in ATC have been used to model 'loss of control' events as problems in adapting control strategies in order to (1) maintain control of actions, (2) transfer control, (3) coordinate and (4) choose new modes of functioning and recovery when control breaks down. These control aspects are useful for debriefing controllers after critical events and identifying system performance flaws that can provide input to ergonomic interventions, such as the design of new air traffic management systems, decision aids and role allocation. © 2011 Springer-Verlag London Limited. Source

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