Scrapping the North Atlantic tracks thanks to Aireon space-based ADS-B

Just a few months ago air traffic controllers were able to shrink the spacing between aircraft flying on the Organized Track Structure routes across the North Atlantic Ocean. Now those same controllers are considering scrapping the tracks completely, ending a decades-long practice of aircraft management in favor of more efficient routings.

Upgrading to more efficient aircraft or switching to biofuels or batteries could lower emissions significantly, but will be costly and may take decades to achieve. Simple tweaks to flight paths are far cheaper and can offer benefits immediately. This is important, because lower emissions from aviation are urgently needed to reduce the future impacts of climate change.

– Professor Paul Williams, an atmospheric scientist at the University of Reading

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The Organized Track Structure (OTS) consists of a set of planned routes coordinated by the UK’s NATS and NAV CANADA, the two groups responsible for managing aircraft as they cross between North America and Europe. Up to a dozen OTS routes are set, potentially changing twice daily to account for traffic patterns. Each flight is allocated to one of the tracks and must maintain that path, even if it is not the most efficient routing for the aircraft. This was born out of necessity in an era where the planes could not be well tracked once they started their crossings. They would be slotted into a crossing and expected to maintain that position, ensuring they did not interact with all the other planes making the trip.

Thanks to Aireon’s space-based ADS-B tracking system, however, NATS and NAV CANADA now know where all the planes are all the time. This allowed for spacing to shrink from roughly 40 nautical miles to just 14nm. This reduced separation requirement allows more planes to fly the most optimal tracks available on any given day, but there is still room to improve. Now the controllers are ready to test the next step in the evolution of traffic management.

Under the new plan the OTS tracks will not be published. There will be no assignments made. Rather than slotting flights into the tracks controllers will allow airline dispatchers to set their own, ideal paths across the ocean.

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As explained by Jacob Young, NATS’ Manager Operational Performance, “[I]n the coming weeks, on days when the traffic levels allow, no tracks will be published either west or eastbound and the airlines will be asked to flight plan based entirely on their optimum route, speed and trajectory.”

This represents a massive operational shift for the airlines and controllers alike, but it was always part of the plan since the Aireon system entered service. And while there is little to celebrate with the current downturn in global air traffic it does help accelerate this testing process.

With just 500 daily flights rather than 1,300 in a typical peak travel period the planning and coordination for OTS track-free days is significantly easier for all parties. So is analysis of the resulting data.

The optimized routes will reduce flight distances by about 200km on average according to a study published in Environmental Research Letters last week. This impacts not only travel time, but also fuel burn and emissions. The cuts are not game-changing in terms of operating efficiency today, but every little bit helps. And the benefits established now will be compounded as traffic levels rebound.