Aircraft engines and airframes have traditionally dominated the function and performance of aircraft. Whilst engines and airframes are still huge considerations in aircraft design and operation, more and more of the functionality of modern aircraft is provided by avionics systems. Critical functions such as automatic flight control, situational awareness, navigation, communication and identification are examples of functionality provided via avionics systems. This book aims to provide a complete coverage of modern avionics systems in a structured fashion to support the work of professional engineers, technicians and aircrew. The book has been written to allow engineers and other technical people to gain an appreciation and understanding of the discipline. Additional references are provided at the end of each chapter to support further reading and investigation as required. The structure of the book is such that it makes an ideal companion to flight manuals used by aircrew to understand their aircraft. Whilst flight manuals describe a particular aircraft and its systems, this book explores the avionics systems more generally and in more detail.