Evaluating the Benefits of Accepting Cruising Flight Levels That Are Not in Compliance with the Hemispherical Rules in the Pacific Airspace

The hemispherical rules require that eastbound flights should use odd thousands flight levels (FLs) and westbound flights should use even thousands FLs. Though these rules improve safety, they could also negatively impact flight efficiency by, for example, reducing the available FLs that can be used to improve efficiency. With improved surveillance and communication capabilities in oceanic airspace, it is possible to use the FLs that do not comply with the hemispherical rules (non-complying FLs). The paper investigates whether doing so in the Pacific airspace could bring benefits to airlines and air traffic controllers. Our analysis showed mixed results. We found that fuel savings would increase as more flights accept non-complying FLs. If all flights accept non-complying FLs, the annual total fuel savings could reach 12.2 million gallons within the Oakland and Anchorage Flight Information Region (FIR). Depending on the price of Jet-A fuel, the monetary value of these fuel savings ranges from 11.25 to 25.66 million dollars. However, we also found that the annual total travel time inside the two FIRs would increase by about 2,070 flight hours. In addition, the workload of air traffic controllers and pilots may also increase as more flights accept non-complying FLs.