Since 2015, London Heathrow Airport has been benefitting from Intelligent Approach, a suite of controller tools to optimise arrivals spacing, developed by NATS and Leidos.
Heathrow is the busiest airport in the world where arriving aircraft are separated using dynamically calculated time intervals, as opposed to set distances. This allows them to be adjusted in real-time to suit the prevailing wind conditions and help maintain the landing-rate.
The challenge
Heathrow is the world’s busiest dual runway airport. Scheduled to around 98% of maximum allowed capacity, up to 1,395 flights a day make use of what are two of the most efficient strips of concrete anywhere in the world. But the flip side of having such a full schedule is that any disruption – such as strong headwinds - can cause knock on effects that ripple through the day resulting in delays and cancellations.
During strong headwind conditions, aircraft fly more slowly over the ground resulting in extra time between each arrival. Having to maintain a set separation distance in those conditions therefore reduces the landing rate.
With headwinds being responsible for 160,000 minutes of delay every year, Heathrow engaged NATS to find a way of improving its operational resilience, boost on time performance and help deliver a better passenger experience, all whilst maintaining the highest levels of safety.
The solution
Together, NATS and Heathrow were the first in the world to separate arriving aircraft by time instead of distance. The Enhanced Time-Based Separation (eTBS) tool within the Intelligent Approach suite, dynamically calculates the optimum safe time interval between arrivals based on real-time wind data and the wake vortex category of aircraft.
In headwinds, when aircraft are flying more slowly over the ground, the distance between arrivals can be reduced, thereby recovering most of the lost capacity while not materially affecting runway separation between arrivals.
By also implementing the re-categorisation of Medium and Heavy aircraft, as enabled under RECAT-EU, , the available benefits have been enhanced and are particularly beneficial at major international airports such as Heathrow. Using another Intelligent Approach tool under development called eTBS Pairwise, we aim to realise further safe separation reductions based upon specific types of aircraft, not just the wake vortex category.
These tools have and will enable Heathrow to boost arrival punctuality and resilience, which reduces operational delays leading to more certainty for their passengers, and a reduction in both aircraft emissions and airborne holding.
Dale Reeson, Head of Airport Operations and Airspace, said: “eTBS has been a joint programme between Heathrow Airport and NATS and is a great example of the benefit of airport and air traffic control working together. “It has helped meet Heathrow’s flight punctuality goals – bringing noticeable benefits to the airport, airlines and passengers alike.”