Commercial aviation has matured rapidly since the introduction of gas-turbine engine technology. The investments required to develop new aircraft have increased exponentially. These investments include capital, human resources across a wide spectrum of competences, infrastructure and time. In this framework, the importance of operational aircraft performance is crucial because the existing technology is locked into a large fleet that is due to operate for several decades into the future. Airplane evolution is therefore inevitable and is proved in several case studies, both in the commercial and in the military world. The issues raised in this book will continue to dominate the debate; we expect considerable changes in the future, from the ATC, to aero-engine technology, to aircraft design, operations and demand management.

Each chapter has illustrated major issues in aircraft flight performance; conclusions have been drawn in each separate instance. To conclude, we wish to mention some key aspects of wider interest.

ROLE OF COMPREHENSIVE ANALYSIS IN AIRCRAFT PERFORMANCE. Performance is what sells an airplane; the ability to predict and verify performance parameters is key to the whole aircraft industry. We have emphasised the fact that the field of comprehensive analysis is not well developed (unlike rotorcraft engineering); the amount of reference data is relatively modest, as reported in the flight manual and in some type certificate documents. However, these data are often insufficient for an accurate engineering analysis. In this book we have attempted tomake advancements in this area and have proposed several numerical methods, validation strategies and sensitivity analyses that can improve the prediction of aircraft performance.