The availability of unmanned air vehicles: a post-case study

An Unmanned Air Vehicle (UAV) is an unmanned remotely controlled, small air vehicle, it has an important role in antisurface warfare. This implies ove r-the-horizon detection, classification, targeting and battle damage assess ment. To perform these tasks several UAVs are needed to assist or interchan ge with each other. An important problem is to determine how many UAVs are needed in this respect. The answer depends on the characteristics of the UA V and its mission. The UAV availability problem is very complex and the usu al method to solve such a problem is simulation. A disadvantage of simulati on is that it can be very time-consuming. Hence it is not very suitable for sensitivity analysis. Moreover, since simulation gives mere approximations and is not very generic, theoretical insights are hardly gained. In this p aper we show how such a complex problem can still be tackled analytically b y using a basic model from reliability theory, viz., a l-out-of-n system wi th cold standby, ample repair facility and general life time and repair dis tributions.