Free Route Airspace (FRA) is a key part of modernising UK airspace. It allows pilots to fly their preferred trajectory between defined entry and exit points in specific areas of airspace, rather than following rigid, predefined Air Traffic Services (ATS) routes. While entry and exit points remain fixed, aircraft operating in FRA – above 24,500 ft – have greater freedom to choose their most efficient route, based on real-time factors such as weather and windspeed.

This flexibility enables airlines to plan fully optimised flight paths, reducing flight time, fuel burn and emissions. The result is a more efficient, responsive airspace system that benefits both the environment and the aviation industry.

Already deployed across West and Scotland, FRA is instrumental to efforts to reduce emissions. In Scotland alone, FRA is expected to reduce CO₂ emissions by 12,000 tonnes annually – the equivalent power used by 3,500 family homes.

To modernise how the UK manages flights at lower altitudes, airspace is being redesigned into a more structured, predictable system – known as Systemised Airspace. This involves the redesign of airspace below 24,500 ft into a systemised network of defined, structured flight paths. By establishing these routes, aircraft can safely fly closer together, increasing airspace capacity and enabling more direct and efficient journeys.

Systemisation reduces the need for real-time or “tactical” interventions from air traffic controllers (ATCOs). Instead, aircraft follow planned routes, allowing pilots to optimise their flight profiles for time and fuel savings. Although aircraft follow set paths, ATCOs will always continue to monitor traffic closely throughout the flight although they are now likely to have to issue fewer instructions to pilots.

Historically, UK airspace was shaped by the position of ground-based navigation beacons and the need for wide flight corridors to ensure safe separation. That legacy system had limited flexibility, precision and efficiency.

Performance Based Navigation (PBN) changes that. Using modern satellite navigation alongside traditional systems, PBN allows aircraft to follow tightly defined routes with pinpoint accuracy. This unlocks a range of benefits: more closely spaced flight paths which can be alternated to provide respite from noise for people on the ground, reduced need for air traffic control intervention, and better use of available airspace.

PBN is essential to systemising UK airspace. It enables continuous climbs and descents, more direct routing and safer, more efficient use of airspace. With PBN, aircraft will no longer need to level off to pass below holding stacks, cutting delays and fuel burn.

Queue and Capacity Management (QCM) plays a vital role in the modernisation of UK airspace by enabling more predictable and efficient aircraft arrivals.

Through the use of advanced technologies, such as arrival streaming, time-based separation, and demand balancing, QCM helps reduce airborne holding and shift delays into more fuel-efficient phases of flight – usually when aircraft are cruising at a higher altitude.

This supports systemisation and the implementation of Free Route Airspace by improving the accuracy of arrival predictions and enabling smoother, continuous descents. By reducing fuel burn, flight time, and CO₂ emissions, QCM contributes to the industry's target of net zero by 2050 and aligns with NATS' broader strategy to deliver a more sustainable and resilient air traffic management system.