<div class="htmlview paragraph">With the increasing complexity of modern combat aircraft flight control systems, the flight trials phase of an aircraft development programme has become much more of an aircraft and systems model validaition exercise. This requires a highly integrated ground and flight test programme with accurate models of the aircraft and its systems and new analysis techniques to enable rapid and effective validation of these models.</div> <div class="htmlview paragraph">This paper describes recent experience at British Aerospace Warton on a number of aircraft programmes which has resulted in the development of effective real lime analysis techniques. These techniques provide the ability to perform in-flight model validation and are currently being used in the EF2000 development programme at Warton.</div>