This book focuses on achieving precision guidance and timely arrival in flight. The content comprehensively describes the civil aircraft flight guidance technology for four-dimensional trajectory-based operation. The main content of this book is the summary of the author's team's research work on flight management systems and flight guidance technology over the past decade, including flight plan analysis and transition path construction, four-dimensional trajectory planning and re-planning, high-precision flight guidance commands calculation, FMS landing system, etc. The theoretical methods described in the book have been verified by pre-research and practical engineering projects, which are of great theoretical significance and engineering application value. This book is used as a reference for engineers engaged in flight control, flight guidance, and flight management research, as well as Masters and Ph.Ds. in related disciplines.