We are developing an aircraft Flight Plan Manager (FPM) that incorporates a variable autonomy plan repair algorithm and provides real-time trajectory adaptation in response to both performance degradation and traffic and weather conflicts. FPM reduces environmental impact, improves safety, and simplifies personal air vehicle (PAV) operation by coupling realistic performance and noise models with intuitive pilot interfaces and robust optimization algorithms. Enhanced situational awareness and detailed procedural guidance improve safety and reduce reliance on specialized pilot knowledge. Reuse of existing navigation and autopilot systems will minimize production cost. Our long-term goal is to develop and validate the models and methods that will make FPM part of every PAV cockpit.