Introducing the principles of communications and navigation systems, this book is written for anyone pursuing a career in aircraft maintenance engineering or a related aerospace engineering discipline, and in particular will be suitable for those studying for licensed aircraft maintenance engineer status. It systematically addresses the relevant sections (Air Transport Association of America chapters 23/34) of modules 11 and 13 of part-66 of the European Aviation Safety Agency (EASA) syllabus and is ideal for anyone studying as part of an EASA and FAR-147-approved course in aerospace engineering. Delivers the essential principles and knowledge base required by Airframe and Propulsion (A&P) Mechanics for Modules 11 and 13 of the EASA Part-66 syllabus and BTEC National awards in aerospace engineering Supports mechanics, technicians and engineers studying for a Part-66 qualification Comprehensive and accessible, with self-test questions, exercises and multiple choice questions to enhance learning for both independent and tutor-assisted study Additional resources and interactive materials are available at the book's companion website at www.66web.co.uk This new and updated third edition provides readers with an overview of the latest key technologies that underpin the functioning of safety-critical systems such as those used in flight management, reporting, navigation, and air traffic control.