As part of the FAA’s Next Generation Air Transportation System (NextGen) initiative, a redevelopment of the high altitude airspace is underway to fully realize the benefits of RNAV navigational capabilities. In an effort to correct the imbalance between the current relatively inefficient airspace design and the capabilities of more modern aircraft (i.e. RNAV), several years ago the FAA created the High Altitude Redesign (HAR) Program to address these concerns above 18,000 feet MSL. The Navigation Reference System (NRS) and NRS waypoints were developed though this program and have been operational since 2005.

NRS waypoints are RNAV waypoints which form a grid through the intersection of lines of latitude and longitude. Currently totaling around 1,600 waypoints, they are deployed in all 20 ARTCCs throughout the continental United States; current density is one waypoint spaced every 30 minutes of latitude and every 2o of longitude. NRS waypoint names consist of two letters followed by two numbers and a final letter (ex. KD54U). Although this waypoint nomenclature is identical in length to traditional RNAV waypoints, their unique construct provides some degree of geographical awareness once trained on the system. In the example above (KD54U), the waypoint is located in the US (K), in Denver ARTCC airspace (D), and located at the intersection of latitude line 54 and longitude line U on the NRS grid.

Although currently the waypoints number around 1600 and are only operational at FL180 and above, the system was originally design for future expansion to 6600 and operation to the surface if desired. Even with the amazing navigational flexibility that the NRS provides, its usage since deployment has been less than expected industry wide. While further expansion is being considered, our research group has been tasked with a study to examine the NRS to determine if there are human factors considerations that need to be addressed as NextGen applications become implemented and the NRS continues to become more widely used.

Phase 1 of this three phase research project is complete and focused on human factors issues with the current NRS grid system and waypoints. Our findings are detailed in a report (http://human-factors.arc.nasa.gov/ihs/flightcognition/Publications/NRSStudyPhase1ReportFinal31110.pdf ). Check back later for information discovered during phase 2 currently underway (mitigation strategies for the issues identified during phase 1) and phase 3 (human factors issues associated with expansion of the NRS grid).

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