NATS has achieved a 20% reduction in average arrival delays at Heathrow Airport following deployment of Pairwise separation technology in December. The system, part of the Intelligent Approach arrivals spacing tool developed with Leidos UK, calculates aircraft separation based on individual aircraft characteristics rather than traditional weight categories.
Analysis of six months of operation shows arrivals with no delay improved by 6.2 percentage points compared to the same period in 2024. Average landing rates during peak morning hours increased by 3.2% from 39.32 to 40.57 arrivals per hour. Carbon dioxide emissions decreased by 18,600 tonnes during the evaluation period.
Pairwise represents a departure from traditional separation standards that rely on six aircraft weight categories. The technology uses specific characteristics of individual aircraft types to calculate safe minimum separation distances. According to NATS, this enables air traffic controllers to reduce separation between certain aircraft pairs while maintaining safety standards.
The system builds on the existing Intelligent Approach platform, which NATS first deployed at Heathrow in 2015. That technology uses dynamically calculated time-based separation and has reduced headwind delays by more than 60% while saving over 45,000 tonnes of carbon dioxide annually.
Gary Harman, head of punctuality and air traffic management at Heathrow, said the technology delivers measurable improvements despite capacity constraints. “Heathrow is operating at capacity and innovations like this are a way to improve punctuality and resilience while reducing our impacts.”
Brendan Kelly, head of queue and capacity management solutions at NATS, described the deployment as delivering value for Heathrow and airline customers. “While there are lots of factors that can influence operational performance, these interim benefits paint a positive picture of the value it is delivering.”
Graham Emmons, managing director for civil operations at Leidos UK & Europe, said Pairwise improves existing runway capacity utilization. “We’re improving the use of existing runway capacity and delivering operational and environmental benefits – contributing to smoother airport operations, reduced fuel burn for airlines, and more punctual journeys for passengers.”
The technology has contributed to Heathrow becoming Europe’s most punctual major airport this year. Peak-time landing rate improvements have added operational resilience by minimizing delay impacts during disruptions.
NATS has deployed Intelligent Approach at Toronto Pearson, Amsterdam Schiphol and Gatwick airports. The company announced a contract with Saudi Air Navigation Services in May to introduce the technology at three Saudi airports. Pairwise has been shortlisted for National Transport Awards in the Digital and Technology Excellence category.
NATS developed Pairwise separation research as part of the Single European Sky Air Traffic Management Research Programme.
