Today, aircraft must fly from one radio-beacon, or VOR, to
another. This is typically not the most direct route, and results in a sort of
zig-zag flight path. With NextGen, navigation will be performance-based,
thereby improving how precisely an aircraft navigates to its final destination,
minimizing course deviation.
RNAV, or Area Navigation, is one of NextGen's improvements. It uses the Global Positioning System to define the fixed ground-based beacons as waypoints. Since the aircraft will not have to fly in-range of every beacon, more direct routing to the final destination will be possible.
RNP, or Navigation Performance, in combination with other NextGen technologies controls how much an aircraft deviates from its fixed flight path. This technology will make closely spaced parallel runway operations possible. In combination with time-based trajectories, aircraft will be able to make real-time adjustments in flight speed, based on changes to the flight schedule, weather conditions, or airspace/airport developments.
@BetterAirports