The U.S. Department of Transportation’s Federal Aviation Administration (FAA) released on July 22, 2003, a "Roadmap for Performance-Based Navigation." This roadmap will allow the development of air traffic procedures pilots can use with onboard technology to navigate to any point in the world, using only geographic coordinates.
"With its high degree of precision, required nav- igation performance, or RNP, allows us to fly more planes, more closely and more safely than ever before," says FAA Administrator Marion Blakey. RNP and area navigation (RNAV) are navigation capabilities that exploit an aircraft’s onboard technology to fly more accurate and predictable flight paths to and from an airport, increasing navigation accuracy and flight path predictability.
RNP and RNAV airspace and procedures– with increasing aircraft use of GPS– will form the foundation for moving toward a satellite-based air traffic management system in the U.S. within two decades.
The FAA will work collaboratively with the aviation community to implement these procedures and to provide near-term operational benefits for users. As air transportation growth resumes in the next few years, RNP will help prepare the FAA and industry to meet increased demand and improve efficiency.
The RNP roadmap, which the FAA delivered within a year, identifies steps and milestones that will transition the U.S. airspace system from today’s reliance on airways running over ground-based navigation aids to a point-to-point navigation concept that takes maximum advantage of advanced automation capabilities aboard aircraft. The roadmap’s implementation timetable is divided into three periods:
The near term, between 2003 and 2006;
The midterm, between 2007 and 2012; and
The far term, between 2013 and 2020.
The near term will mark a beneficial change in operations, as the FAA implements a first set of public RNAV and RNP procedures in all phases of flight. Also in the near term, the FAA will continue to develop enabling criteria and guidance for more advanced RNAV and RNP operations.
In the domestic en route environment, the FAA will, in the near term, publish the first RNAV routes based on a series of waypoints that are charted and included in navigation databases (aircraft and ground systems). These designated routes will provide flexibility and efficiency in the airspace. Use of RNAV and RNP in the terminal domain optimizes airspace design through better use of arrival and departure corridors. Standard terminal arrivals and standard instrument departures that apply RNAV and RNP improve safety, capacity and flight efficiency. These procedures reduce the risk of communication errors for pilots and controllers and take advantage of 3-D flight management by the aircraft system.
For the approach segment, the FAA has committed to providing vertically guided approaches to all runway ends that support IFR operations. New and modified procedures, in the near term, will apply techniques such as offset final approach course, step-down fixes, varying angles of descent, and linear obstacle clearance surfaces. These procedures will mitigate obstacle and environmental constraints at certain locations and lower existing minima, in particular for the more maneuverable aircraft.
In the near term the aviation community is faced with a mixed-capability environment. As a result of current aviation economic conditions, additional investments in avionics capabilities by many operators will not be forthcoming in the immediate future, except to the extent that they are included as standard equipment on new aircraft. So a mixture of RNAV and non-RNAV capability will continue for several years. Starting in the midterm, aircraft capability enhancements by various operators may resume, especially as they formulate business cases and strategies based on benefits.
The situation faced in the near term presents opportunities as well as challenges. There are opportunities to provide benefits to those aircraft owners and operators who have invested in advanced capabilities and training and who expect to participate in new procedures. Those operators with less capability will not realize the specific benefits but will continue to enjoy their current level of service and may benefit from reduced congestion.
The FAA and industry must assess global differences in air traffic operations, ground infrastructure and services in terms of their effect on standardization of aircraft capability. They need a consensus on how to achieve operationally feasible airspace and procedure solutions when and where mixed equipage exists. The FAA is committed to providing benefits to operators who are capable of performance-based navigation without adversely impacting non-capable operators. This involves ongoing benefits, tradeoffs and policy considerations. The FAA and industry will update the road-map periodically, based on the evolution of aircraft capabilities, lessons learned and key decisions.
Jeffrey T. Williams manages the FAA’s Required Navigation Performance Division, ATP 500.