The Aircraft Engineering Principles and Practice Series provides students, apprentices and practicing aerospace professionals with the definitive resources to advance their aircraft engineering maintenance studies and career. This book provides an introduction to the principles of communications and navigation systems. It 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. The book systematically addresses the relevant sections (ATA chapters 23/34) of modules 11 and 13 of part-66 of the EASA syllabus. It is ideal for anyone studying as part of an EASA and FAR-147 approved course in aerospace engineering.