Large and complex infrastructures as industry plants and hospitals are vulnerable to natural, man-made disasters, and causality events. In this paper, we present a solution addressing the guiding personnel during maintenance and/or emergency conditions. The aim is to reduce the time needed to react and to cope with organization and maintenance support, while facilitating communication, and indoor / outdoor navigation. The solution is based on the formalization of protocol, the modelling of knowledge for navigation, the algorithms and the development of a mobile application and corresponding server device for integrated indoor/outdoor navigation. The navigation algorithms are based on low costs mobile sensors and Adaptive Extended Kalman Filter. The solution has been validated and tried out within a large medical infrastructure, thus demonstrating the validity of the identified modalities and procedures, measuring the advantage from both qualitative and quantitative aspects. The indoor navigation solution has been compared with other former solutions based on classical Kalman and dead reckoning. Keywords maintenance and emergency management, mobile emergency, indoor / outdoor navigation.