This book describes the performance of an airplane during an entire flight that includes take-off, climb, cruise, descent, and landing. It provides a succinct theory of aerodynamics, keeping the mathematics to a minimum. It analyzes lift and drag from both the vorticity point of view, and the pressure distribution point of view. Various forms of drag are considered, including compressibility drag. Jet engines are briefly described, including the various allowed thrust ratings. The theory provides the basis to analyze the requirements for optimum performance regimes during all the stages of the flight mission for minimum fuel and/or minimum cost, such as optimum climb, cruise, maximum range, long range cruise, and descent speeds. Optimum rate of climb, altitudes, rate of descent, etc. are also described. The book includes an original chapter on aircraft stability and Mach excursions in the operating range. Climb and descent are analyzed, including optimum speeds, rate of climb, rate of descent, etc. Take-off and landing are analyzed, which includes the nomenclature of the concepts for the various segments and speeds for both. In an appendix are provided some more elaborate mathematical expressions used in aerodynamics. The book is intended for pilots, airline personal, students in aeronautics, and to people having a general interest in aviation. The book reflects the author's practical experience of flying for three decades as an active aircrew member for EI-Al, the Israel Airlines.