Safety-Critical systems are systems whose failure would provoke injury or death to human beings. The Personal Air Vehicle (PAV) represents a new generation of small aircrafts being conceived to extend personal air travel to a much larger segment of the population proposing new concepts of interaction and communication in aviation. In this domain, communication is a critical factor especially regarding the communication of users with the vehicle through its interfaces. This paper presents a case study in which we model the communication structure of this type of system, aiming at supporting the design of interaction in safety-critical systems. The approach is based on Semiotic theory and artefacts. 465472China Association for Information Systems,China Information Economics Society,et al.,International Federation of Information Processing, WG8.1,National Natural Science Foundation of China,University of Reading(2007) Personal Air Vehicle, , http://cafefoundation.org/v2/pav_home.php, Accessed 23 MarchCordeiro, J., Filipe, J., The semiotic pentagram framework - A perspective on the use of semiotics within organisational semiotics (2004) Proceedings of the 7th International Workshop on Organisational SemioticsJohnson, C.W., (2003) Failure in Safety-critical Systems: A Handbook of Incident and Accident Reporting, , Glasgow University PressCarver, L., Turoff, M., Human-computer interaction: The human and computer as a team in emergency management information systems (2007) Communications of the ACM, 50 (3). , ACM PressSalles, J.P., Baranauskas, M.C.C., Bigonha, R.S., Towards a communication model applied to the interface design process (2001) Knowledge-Based Systems, 18, pp. 455-459Liu, K., (2000) Semiotics in Information Systems Engineering, , Cambridge University PressBaranauskas, M.C.C., Salles, J.P., Liu, K., Analysing communication in the context of a software production organisation (2002) 4th International Conference on Enterprise Information Systems, pp. 202-209. , Kluwer Academic PublishersHarrison, M., Aspects of human error: A brief introduction (2004) Workshop on Human Computer Interaction and Dependability, , http://www.laas.fr/IFIPWG/Workshops&Meetings/46/03-Harrison.pdf, Accessed 26 April 2006Guimarães, M.S., Baranauskas, M.C.C., Martins, E., A communication-based approach to requirements elicitation for safety-critical systems (2007) Proceedings of 10th International Conference on Organisational Semiotics ICOSGuimarães, M.S., Baranauskas, M.C.C., Martins, E., Communication-based modelling and inspection in critical systems (2008) 10thInternational Conference Enterprises on Information Systems, , INSTICC Press, PortugalGuimarães, M.S., Baranauskas, M.C.C., Martins, E., Interaction in critical systems: Conquests and challenges (2007) 9th International Conference Enterprises on Information Systems, pp. 170-175. , INSTICC Press, PortugalPalanque, P., Paterno, F., Fields, R., Designing user interfaces for safety critical systems (1998) CHÍ98 Workshop, , ACM PressBonacin, R., Simoni, C.A.C., Melo, A.M., Baranauskas, M.C.C., Organisational semiotics: Guiding a service-oriented architecture for e-government (2006) 9thInternational Conference on Organisational Semiotics, pp. 47-58Stamper, R.K., Social norms in requirements analysis - An outline of measur (1993) Requirements Engineering Technical and Social Aspects, , Academic PressSalles, J.P., O modelo fractal de comunicação: Criando um espaço de análise para inspeção do processo de design de software (2000) Tese de Doutorado, , Universidade Federal de Minas GeraisYoung, S.D., Quon, L., (2006) Aviation Safety Program, Integrated Intelligent Flight Deck, , http://www.hq.nasa.gov/office/aero/nra_pdf/iifd_tech_plan_c1.pdf, technical plan summary. Accessed 26 may 2006Stamper, R.K., (1973) Information in Business and Administrative Systems, , John Wiley and Sons Inc, New YorkHewett, T.T., Baecker, R., Card, S.K., Carey, T., Gasen, J.G., Mantei, M.M., Perlman, G., Verplank, B., Curricula for human-computer interaction (2007) ACM SIGCHI, , http://sigchi.org/cdg/cdg2.html, Accessed 12 may 2007Baranauskas, M.C.C., Schimiguel, J., Simoni, C.A.C., Medeiros, C.M.B., Guiding the process of requirements elicitation with a semiotic approach (2005) 11thInternational Conference on Human-Computer Interaction, 3, pp. 100-111. , Lawrence Erlbaum IncLiu, X., (2001) Employing Measur Methods for Business Process Reengineering in China, , PhD dissertation. University of Twente, Enschede, Netherlands