Enhancing NextGen RNAV Capabilities: Human Performance Evaluation of NRS Waypoint Nomenclatures

Abstract

As part of the Next Generation Air Transportation System (NextGen) initiative, a redevelopment of the high-altitude airspace is underway to realize the benefits of area navigation (RNAV) capabilities. Three nomenclatures were evaluated as possible alternatives to the current waypoint nomenclature used in the Navigation Reference System (NRS). A part-task study was conducted to assess if speed of NRS waypoint location on an en route chart, speed of flight management system (FMS) entry, number of FMS entry errors, and NRS waypoint reroute use were different among the nomenclatures tested. Overall preference was also assessed.

Notes

1. ¹Traditionally named RNAV waypoints are referred to as RNAV waypoints throughout the article to distinguish them from NRS waypoints.

2. ²NRS waypoints are used exclusively within the United States, but during their development it was assumed that other countries might chose to adopt them as well. This is no longer expected to happen.

3. ³Numbers and letters indicating latitude and longitude are not associated with the current latitude and longitude numbering system and are used solely in the NRS grid. See Boetig and Timmerman (2003) for information about how numbers and letters were assigned to lines of latitude and longitude, respectively, in the NRS grid.

4. ⁴Because ARTCC identifiers are of use to one set of users (air traffic control [ATC]), we wanted to assess at least one alternate nomenclature that included them. Doing so, however, required that the within-state numbering system be accomplished with only two characters, which does not yield enough remaining numbers in a five-character nomenclature to accommodate the future expansion of the grid beyond 99 waypoints per state.

5. ⁵In normal operations it would be considered unusual for ATC to ask a pilot to reroute themselves; however, to assess if pilots would use NRS waypoints in a weather reroute situation, we asked pilots to choose their own reroute.

6. ⁶Density was only used as a variable in the waypoint finding task. This variable was controlled and used as a counterbalance measure to ensure waypoints were similarly difficult to find across the four nomenclatures. NRS waypoints were located in one of three different densities based on the number of “bits„ of information within a 1 inch radius of the NRS waypoint on the en route chart.

7. ⁷Participants were allowed to select more than one nomenclature type when asked if any nomenclatures were easier or harder.