NATS’ introduction of Pairwise separation at London Heathrow marks a breakthrough in aviation efficiency, increasing landings and reducing CO2 emissions through more precise aircraft spacing, with future developments promising further environmental benefits.
In August 2025 NATS introduced Pairwise separation at London Heathrow, a world-first refinement to the Intelligent Approach arrival‑spacing tool that has delivered measurable improvements in on‑time performance and emissions, according to a NATS press release. The six‑month analysis cited by NATS shows a 3.2% increase in average landing rate between 06:00 and 10:00, a 6.2 percentage‑point rise in arrivals with no delay, a 19.6% fall in average delay per arrival and a 19.3% reduction in average CO2 emissions from airborne holding.
Pairwise changes how final‑approach separation is determined. Rather than sorting aircraft into broad wake‑based categories, Pairwise uses the specific characteristics of each aircraft type to apply more granular separations between particular pairs of aircraft, allowing controllers to safely tighten spacing for some combinations and thereby increase tactical runway capacity. According to NATS, that additional capacity has translated into improved resilience and efficiency during busy morning peaks at Heathrow.
The Pairwise deployment builds on a decade of operational experience with Intelligent Approach, the time‑based spacing suite developed by NATS in partnership with Leidos. According to Intelligent Approach marketing materials, the system has been in continuous operation at Heathrow since March 2015 and has previously delivered an average tactical gain of around two extra landings per hour in all wind conditions, a 1.5–2.5% improvement in punctuality and aggregate savings in final‑approach separation that extend the airport operating day by roughly 23.5 minutes. Leidos and NATS say the family of modules integrates with existing air traffic management systems and has won industry awards for transport innovation and Single European Sky contributions.
For airports seeking further fuel and emissions benefits, NATS and Leidos point to an emerging capability known as Curved Approach. Where Intelligent Approach currently supports predominantly straight‑in ILS approaches, Curved Approach is being developed to sequence arrivals that use Required Navigation Performance (RNP) , highly accurate, satellite‑based flight paths that can deliver substantial fuel and emissions savings but, in some deployments, have reduced runway throughput. Curved Approach aims to extend time‑based sequencing beyond the runway centreline into the terminal airspace, enabling controllers to manage multiple RNP and ILS streams via separation indicators on radar displays so that carbon savings do not come at the expense of capacity.
The companies characterise Curved Approach as an early‑stage but potentially transformative extension of the Intelligent Approach concept. Industry data and vendor material emphasise two complementary objectives: preserving the environmental advantages of RNP procedures while recovering the tactical throughput that fixed lateral trajectories can sometimes constrain.
For airport operators and air navigation service providers focused on industrial decarbonisation, the Heathrow experience with Pairwise underlines how finer‑grained sequencing logic can yield both operational and environmental dividends. The broader Intelligent Approach programme, backed by three decades of collaboration between NATS and Leidos, positions time‑based spacing and its forthcoming extensions as practical tools for airports seeking to reconcile capacity constraints with emissions‑reduction commitments.
- https://www.internationalairportreview.com/article/301495/intelligent-approach-delivers-on-time-boost-and-carbon-cuts/ – Please view link – unable to able to access data
- https://www.nats.aero/news/press-releases/nats-delivers-on-time-boost-and-carbon-cuts-with-world-first-at-heathrow/ – In August 2025, NATS introduced Pairwise separation at Heathrow Airport, a world-first in air traffic control. This innovation has led to significant improvements, including a 3.2% increase in the average landing rate between 6 am and 10 am, a 6.2 percentage point improvement in arrivals with no delay, a 19.6% reduction in average delay per arrival, and a 19.3% decrease in average CO₂ emissions from airborne holding. These advancements have enhanced operational efficiency and environmental sustainability at Heathrow.
- https://www.intelligentapproach.aero/about/ – Intelligent Approach is an arrival spacing tool developed by NATS and Leidos, designed to optimise the gaps between aircraft arriving at an airport. First deployed at London Heathrow in 2015, it has since been recognised as a multi-award-winning solution supporting airports worldwide. The tool integrates seamlessly into Air Traffic Management systems, offering a family of functional modules tailored to each airport’s unique needs, thereby maximising operational resilience and efficiency.
- https://www.leidos.com/markets/aviation/intelligent-approach – Leidos, in partnership with NATS, developed Intelligent Approach, a suite of adaptive controller tools including the world’s first implementation of time-based separation. This technology enables air traffic controllers to optimise aircraft arrival sequences, increasing runway capacity and reducing delays. It also contributes to environmental sustainability by decreasing fuel consumption and emissions through improved predictability and reduced airborne holding. The system has been recognised with awards such as the Institute of Engineering and Technology (IET) Transport Award and the Single European Sky (SES) Award.
- https://www.intelligentapproach.aero/provensolution/ – Intelligent Approach has been in continuous operation at Heathrow since March 2015, delivering significant operational benefits. These include an average tactical capacity gain of 2 aircraft landings per hour in all wind conditions, an improvement of 1.5-2.5% in airport punctuality, and an average saving of over 1,410 seconds per day in arrival separation on final approach. This equates to extending Heathrow’s operating day by 23.5 minutes, enhancing operational resilience and efficiency.
- https://www.intelligentapproach.aero/partnership/ – NATS, the UK’s leading air navigation services provider, and Leidos, a leading technology provider, have collaborated for over 30 years to develop Intelligent Approach. This partnership combines NATS’ operational expertise with Leidos’ engineering and technology excellence, resulting in a groundbreaking airport solution. Intelligent Approach was first deployed at London Heathrow in 2015, marking the world’s first implementation of time-based separation, and has since been recognised as a multi-award-winning arrival spacing tool supporting customers globally.
- https://www.intelligentapproach.aero/provensolution/ – Intelligent Approach has been in continuous operation at Heathrow since March 2015, delivering significant operational benefits. These include an average tactical capacity gain of 2 aircraft landings per hour in all wind conditions, an improvement of 1.5-2.5% in airport punctuality, and an average saving of over 1,410 seconds per day in arrival separation on final approach. This equates to extending Heathrow’s operating day by 23.5 minutes, enhancing operational resilience and efficiency.
Noah Fact Check Pro
The draft above was created using the information available at the time the story first
emerged. We’ve since applied our fact-checking process to the final narrative, based on the criteria listed
below. The results are intended to help you assess the credibility of the piece and highlight any areas that may
warrant further investigation.
Freshness check
Score:
9
Notes:
The narrative is based on a press release from NATS, dated August 2025, detailing the deployment of Pairwise separation at Heathrow Airport. This press release is the earliest known publication of this specific information. The content has been republished across various reputable outlets, including CANSO ([canso.org](https://canso.org/nats-delivers-on-time-boost-and-carbon-cuts-with-world-first-at-heathrow/?utm_source=openai)) and Aerospace Testing International ([aerospacetestinginternational.com](https://www.aerospacetestinginternational.com/news/nats-delivers-on-time-boost-and-carbon-cuts-at-heathrow.html?utm_source=openai)). The presence of the press release indicates a high freshness score.
Quotes check
Score:
8
Notes:
The narrative includes direct quotes from NATS and Leidos UK representatives. These quotes appear in the original press release and have been consistently used in subsequent publications, indicating they are not exclusive to this narrative. The consistent wording across sources suggests the quotes are reused, which may affect originality.
Source reliability
Score:
10
Notes:
The narrative originates from NATS, a reputable air traffic service provider, and is corroborated by multiple reputable outlets, including CANSO and Aerospace Testing International. The consistent reporting across these sources enhances the reliability of the information.
Plausability check
Score:
9
Notes:
The claims about the deployment of Pairwise separation at Heathrow and its benefits are supported by multiple reputable sources, including NATS’ own publications and industry analyses. The reported improvements in on-time performance and reductions in carbon emissions are consistent with the capabilities of the Pairwise system as described in these sources.
Overall assessment
Verdict (FAIL, OPEN, PASS): PASS
Confidence (LOW, MEDIUM, HIGH): HIGH
Summary:
The narrative is based on a recent press release from NATS, detailing the deployment of Pairwise separation at Heathrow Airport. The information is corroborated by multiple reputable sources, and the claims made are plausible and supported by evidence. The content is accessible without paywalls and is of a factual news report nature. The use of direct quotes from the press release suggests some content reuse, but this does not significantly impact the overall assessment.
