Oceanic Flight

User Preferred Routes (UPRs)

User Preferred Routes are customer designed for each individual flight in order to meet the specific needs of the aircraft for that flight, including fuel optimisation, cost-index performance, or military mission requirements.

UPRs are calculated based on factors such as forecasted winds, aircraft type and performance, convective weather and scheduling requirements.

UPRs are frequently used in oceanic flights where limited air traffic control operations previously required that aircraft fly on fixed routes. The implementation of ground and airborne improvements such as automatic dependent surveillance and other technologies have contributed to the enhancements in UPRs.

When UPRs are used to optimise fuel consumption the savings in greenhouse gas emissions can be substantial. For example, in 2008 Air New Zealand projected that, despite a number of operational restrictions, the implementation of UPRs between New Zealand and Japan would yield a total annual saving in fuel burn of 1,090,000 kg or, based on International Air Transport Association's figures for emissions, 3,444,400 kg less CO2 emissions.

Dynamic Airborne Reroute Procedures (DARP)

A coordinated oceanic in-flight procedure designed to take full advantage of updated atmospheric conditions. Typically, flight plans are filed well before an aircraft's departure time. Frequently, new upper wind forecasts are available after the flight plan is filed or the aircraft departs.

Dynamic Airborne Reroute Procedures allows aircraft to adjust their present position to a new point in order to realise savings in fuel or time. This is coordinated by the airlines with the flight crew, and sent to air traffic control as a request to change route from the aircraft.

When fully realized, the DARP can provide significant savings in fuel and emissions. A recent Air New Zealand sample analysis concluded that 58% of all flights from Auckland to North America resulted in an average fuel burn reduction of 453kg per flight, or roughly 1431kg of CO2 emissions.

Performance Based Navigation (PBN) Separation Reductions

Improvements to communications, navigation, surveillance and air traffic management systems have enabled major separation reductions in the oceanic environment.

Depending on the required navigation performance (RNP) each aircraft can have different separation standards and target levels of safety, this is called performance based navigation.

When equipped with the necessary automatic dependant surveillance technology, aircraft meeting the RNP can be safely separated at much closer distances than aircraft that do not meet the requirements.

Qualified aircraft navigating in airspace where these separation reductions have been implemented achieve significantly greater efficiencies and this is reflected in lower fuel burn and reduced emissions.

Reduced Vertical Separation Minima (RVSM)

Improvements in the modern fleet of aircraft, new procedures and monitoring requirements have all allowed for a reduction of vertical separation between aircraft operating at certain heights. This standard, known as Reduced Vertical Separation Minimum, allows the vertical spacing of qualified aircraft to be reduced from 2000ft to 1000ft in airspace where the standard has been implemented.

Oceanic RVSM allows aircraft to fly closer to fuel efficient altitudes, and execute smaller climbs, which require less fuel.

Flexible Track Systems

In an oceanic environment where the use of UPRs is not feasible, flexible track systems can provide a more efficient alternative than fixed air traffic services routes.

Flexible tracks allow an aircraft to ride the winds on long distance flights. Published every day they provide airlines with 'non-fixed' air traffic routes that are optimised for the weather conditions and can deviate from the normal fixed or direct routes by hundreds of kilometres. This system is designed to laterally separate aircraft from one another to accommodate high traffic density. Flexible tracks have been proven to improve flight time and reduce fuel usage.