More landings, lower emissions: NATS new ATC aircraft spacing system delivers at Heathrow
August 14, 2025
NATS, the UK air navigation service provider, has hailed the success of an aircraft separation procedure at London Heathrow Airport, which it says has cut delays and maximised the number of aircraft movements at the constrained London airport.
The pioneering air traffic control technique introduced at Heathrow is delivering improved punctuality, reduced carbon emissions and greater resilience to disruption, according to the newly released NATS figures.
NATS began using ‘Pairwise’ separation at the west London hub in December 2024 as part of the Intelligent Approach arrivals spacing tool developed with Leidos UK.
Controllers were given the tools to determine the minimum safe distance between aircraft based on the performance characteristics of each specific type, rather than the traditional six weight-based categories.
By tailoring separation to individual aircraft, NATS says it has been able to safely shorten the gap between some arrivals, improving runway throughput and reducing airborne holding.
Intelligent Approach, first introduced at Heathrow in 2015, uses dynamically calculated time-based separation to cut headwind delays and reduce emissions.
Its adoption at other major airports, including Toronto Pearson, Amsterdam Schiphol and Gatwick, has delivered similar operational improvements. The system is also being prepared for deployment at three airports in Saudi Arabia following a contract signed earlier this year.
Delays reduced at Heathrow Airport
An analysis of the first six months of operations compared with the same period in 2024 shows the proportion of flights landing without delay has risen by more than six percentage points, the average arrival delay has fallen by almost 20%, and CO2 emissions are down by 18,600 tonnes.
At peak times, Heathrow managed to accommodate an extra landing aircraft every hour.
In fact, between January and May 2025, Heathrow’s peak morning landing rate between 06:00 and 10:00 rose from an average of 39.32 arrivals per hour in the same period of 2024 to 40.57, an increase of 3.2%.
The proportion of flights arriving without any delay improved from 17.84% to 24.04%, a gain of 6.2 percentage points.
Average arrival delays fell from 5.55 minutes to 4.46 minutes, representing a 19.6% improvement.
Carbon emissions per flight also dropped significantly, from 1,240kg of CO2 to 1,000kg – a reduction of 19.3%.
Strengthening resilience during disruption
Heathrow, which is already operating at full capacity, has become Europe’s most punctual major airport in 2025 so far, with NATS crediting Pairwise for adding “tactical capacity” and strengthening resilience during disruption.
,“Making sure passengers arrive on time is fundamental to making every journey better,” says Gary Harman, head of punctuality and ATM at Heathrow “Working with NATS, we can already see the incremental improvements that Pairwise is helping to deliver.
“It’s no secret that Heathrow is operating at capacity, and innovations like this are a great way to improve punctuality and resilience while reducing our impacts.”
Brendan Kelly, head of queue and capacity management solutions at NATS, said: “Pairwise was another world first deployment for NATS and while there are lots of factors that can influence operational performance, these interim benefits paint a very positive picture of the value it is delivering for Heathrow and our airline customers.
“Our job now is to continue evaluating the tool to understand where we can deliver even greater operational and environmental benefits over the busy summer period and beyond.”
