Integration of the “Constant Radius ARC to a Fix” (RF) navigation leg type into NextGen

Air transportation system authorities throughout the world are becoming increasingly focused on improving the efficiency of air operations to enhance the safety and capacity of their systems and also respond to environmental concerns, all while meeting the demands of the increasingly large traveling public. A critical component to improving efficiencies within air transportation systems is the implementation of a performance-based navigation (PBN) concept. That concept leverages the navigation and performance capabilities of the aircraft by structuring the airspace such that the aircraft can maneuver efficiently with minimal fuel expenditure from takeoff to landing. The US Next Generation Air Transportation System (NextGen) and Europe's Single European Sky Air Traffic Management (ATM) Research Initiative (SESAR) are focused on a PBN design for future airspace operations. One key element of those future airspace designs is a specific aircraft navigation capability that allows the aircraft to traverse over the ground on a fixed ground path consistently, predictably, and reliably while turning. That capability is referred to as a "Constant Radius ARC to a Fix (RF) navigation leg. When incorporated into an instrument procedure design, the RF leg is used by the aircraft's flight management computer system (FMS) to consistently fly the turn over the same ground track. This accommodates avoidance of environmentally sensitive areas or other restricted airspace and also provides for the flexibility to shorten the time and miles traveled by the aircraft thus reducing fuel burn and emissions. Over the past few years, the RF leg has been available only to specially qualified operators and aircraft. However, recent innovative action by the FAA and its aviation industry partners are promoting the RF leg for incorporation into public instrument procedure designs so that all segments of the industry can take advantage of the operational enhancements realized by instrument procedures containing the flexible RF leg. This paper describes the RF leg, how it can be implemented into instrument procedure designs for use by the aircraft navigation systems and the benefits to current and future air transportation systems when it is made available to all aviation segments.