Effect of Adding Gateways on Air Traffic Flows Over the North Pacific Ocean

The North Pacific (NOPAC) oceanic airspace has a high traffic demand between Asia and North America, and its capacity is limited by the non-radar air traffic control environment. Improvements in satellite-based navigation and datalink services have resulted in a reduction in the aircraft minimum separation standard from 185.2 km (100 NM) to 42.6 km (23 NM); moreover, with the adoption of more capable systems, airspace design and flight operations are being modified to take advantage of the lower minimum separation. The NOPAC airspace is currently being restructured based on the 42.6 km (23 NM) standard. However, the “gateway” points between the oceanic and radar-controlled airspaces continue to be at 111.1 km (60 NM) intervals in the Japanese airspace. In this study, we seek to design a gateway configuration that improves efficiency for both individual flights and the oceanic airspace. Concretely, we propose additional gateways to exploit the 42.6 km (23 NM) standard. We conducted a fast-time simulation study to examine the effect of additional gateways using three models of the adjacent NOPAC airspace, viz., a baseline configuration with three parallel oceanic airways at 92.6 km (50 NM) intervals and the existing gateways, and two configurations with our proposed gateway alignment: four parallel airways at 46.3 km (25 NM) intervals reflecting current NOPAC restructuring plans, and a proposed free route airspace (FRA) model without fixed airways. The results showed that increased flight-planning flexibility due to the addition of gateways and the removal of fixed airway constraints allowed for more optimal flight routes with lower fuel consumption and flight time; thus, the FRA model provided the highest average fuel benefit for individual flight routes. However, flights choosing optimal routes tended to favor a small number of gateways, thereby increasing the concentration of westbound traffic in NOPAC. Nonetheless, the overall fuel benefit derived from the selected routes outweighed the penalties incurred from the necessity of cruising at lower-than-planned altitudes for deconfliction.