Anyone flying between North America and Europe at FL330 and below may do so outside the North Atlantic’s Organized Track Structure (OTS) starting March 1, giving operators the flexibility to file a random route plan and choose any trajectory that suits them thanks to Aireon’s real-time satellite-based ADS-B surveillance system.
The OTS serves as an invisible multi-lane “motorway” that connects Europe and North America. Each day, UK NATS and Nav Canada create up to 12 tracks for westbound and eastbound traffic, designed to take advantage of the day’s jet stream and give airlines an efficient route across the ocean. The tracks provide a predictable operating environment for both ATC and aircraft operators, but the concept hasn't changed much since its inception in the 1960s.
However, the system’s evolution took a giant leap with the 2019 introduction of ADS-B to monitor North Atlantic air traffic. According to UK NATS operational performance manager Jacob Young, the method has allowed NATS to safely reduce separation distances from about 40 nm to 14 nm, offering aircraft more speed and trajectory flexibility. As a result, more flights have taken advantage of the best routes, but still while flying within an OTS environment.
While UK NATS and Nav Canada have long aspired to move away from the traditional OTS system in favor of satellite-based surveillance, doing so during the Covid pandemic—as transatlantic traffic at its nadir in 2020 dropped to as little as 200 flights a day instead of the usual 1,300—made for what Young called a substantially more straightforward proposition for the air traffic service providers and the airlines.
In a February 3 blog, Young called the last three years “the most transformational” in the history of North Atlantic air traffic operations. Last March 9, UK NATS organized no westbound flight tracks across the North Atlantic for the first time since at least the 1960s as it prepared to accelerate the possible disbandment of the OTS. The ability to fly outside the OTS route structure as of March 1 marks the next step in the ATC organizations’ effort.
“Even though there have never been any restrictions on flight planning in relation to random routes crossing the OTS, some airline operators have internal systems or procedures that prevent them from filing across OTS tracks with active flight levels,” explained Young. “This change means anyone operating at those levels will have the flexibility to file a random route plan and choose the trajectory that suits them.”
The ability to fly non-OTS tracks will result in considerable fuel savings and a dramatic reduction in CO2 emissions, according to a 2021 research paper appearing in the scientific journal Environmental Research Letters. According to the study's findings, the use of wind-optimized tracks would reduce North Atlantic flight times considerably, even compared with today’s most efficient ATM tracks.
The study concluded that using time optimization could result in a 0.7 to 16.4 percent reduction in air distance through each daily wind field, depending on flight direction and chosen ATM track. Considering the 3,833,701 seats provided between New York and London in 2019 and the amount of CO2 an economy-class return flight between those two cities generates according to ICAO calculations, the use of air-distance-optimized routing results in a 1.7 percent annual reduction in CO2 for westbound flights and a 2.5 percent reduction for passengers flying east. That amounts to a total savings of 6.7 million kg of CO2 over 91 days.
