In 2015, airline tech giant Leidos and leading air navigation service provider NATS developed an incredible technology that changed how air traffic controllers were able to safely achieve a major increase in airport landing capacity without having to invest in new airport infrastructure. The approach was a simple one, but as with most game-changing improvements, no one had ever fully implemented it before.
Based on research and extensive data analysis, it was determined that the best way to combat disruptions was to introduce a time-based separation between planes. This was rolled out at Heathrow in 2015, and so far, it’s estimated to have reduced delays in strong headwind conditions by approximately 60%. It has had a positive environmental impact, saving around 47,000T of CO2 emissions and approximately 15,000T of fuel annually as well as reducing noise pollution by less aircraft in holding stacks.
Airport Technology caught up with Leidos principal engineer Richard Leonard to see just how this technology developed.
Yes. There is nothing else in the market at the moment that provides time-based separation. Heathrow is currently the only airport in the world that operates with it. Everywhere else applies fixed distance-based separation between aircraft.
Aircraft are grouped into Wake categories based predominantly upon their weight, ranging from light through to super heavy. Regulations stipulate that between a particular pair of aircraft you must apply a minimum separation ranging between three and eight miles. The minimum separation depends on the categories of aircraft – the larger the lead aircraft and the smaller the follow-on aircraft, the larger the gap must be. Between something like an A380 (super-heavy) and a Beech (light) aircraft, you would have to have eight miles between them. This is Distance Based Separation and does not take into account meteorological factors, which can allow closer safe spacing.
Instead of using this model like everyone else does, we use the same underlying set of rules, but calculate exactly what the winds are actually doing all along the approach path at that point in time, and use that information to safely separate the aircraft by a fixed time interval rather than a fixed distance. For example, four miles spacing between two aircraft at a steady 160 knots approach speed will take 90 seconds to fly under normal headwind conditions. But with a strong headwind on the approach path, it takes longer to fly the same distance so capacity is lost resulting in delays and increased airborne holding which creates extra CO2 emissions.
With time-based separation, we dynamically adjust the distance separation for the prevailing wind conditions, maintaining a safe time interval between the aircraft. So the distance spacing between aircraft in headwinds is reduced but the time interval stays the same as it would be in lighter wind conditions. This recovers most of the lost capacity enabling the environmental and delay savings. The system also uses the latest wake vortex separation standards (RECAT EU) which optimize the required spacing between different categories of aircraft adding to the benefits.
In the case of Heathrow, the savings provide additional tactical landing capacity equivalent to nearly 30 minutes more landings which also adds to the resilience of the operation and reduces the likelihood of running the operation later into the night period.
How was the Intelligent Approach technology developed?
We used our experience of approach spacing tools coupled with the extensive research performed by NATS as our starting point. In the first month or so, we concentrated on defining the user requirements and ensuring our proposed development was what the Air Traffic Controllers would feel confident in adopting. We use this knowledge in conjunction with the NATS research to implement the changes in an agile iterative development cycle, demonstrating capabilities as we went.
The agile process allowed the team to refine the user requirements and arrive at the solution that had been designed by controllers for controllers so it was something that they actually wanted.
What impact does the Intelligent Approach have on day-to-day operations for air traffic control?
It provides a more efficient operation. We perform all the calculations and give them to both Terminal Control and the control tower at the airport. We provide them with an on-screen indicator which shows the safe separation distance to be applied between a pair of aircraft. We have found that just having that indicator on the screen, even in still winds, improves the efficiency of the operation overall.
Since we began operation, there have been no tactical cancellations due to headwinds. The steady improvement in efficiency and improved resilience to headwinds has led to less aircraft needing to be stacked, resulting in a major reduction of CO2 emissions, and also means that Heathrow can achieve 2 more landings per hour making the operation more resilient.
Do you see this technology advancing further?
Yes, IA is a family of tools with a continuous development roadmap adding features as user demand arises. Currently we are in the process of making some significant improvements. The first one of these is to introduce what is called pairwise separations. Rather than using the current 6 broad Wake categories where an Airbus A333 (heavy) followed by a Boeing 763 (lower-heavy) needs four miles between the two of them. Pairwise uses the individual aircraft types thus allowing the Wake separation to be tailored more precisely, using this example, this can be safely reduced to 3NM miles.
Are there other airports using the Intelligent Approach?
We’re working with Nav-Canada for Toronto Pearson airport and with LVNL the Dutch ANSP for Schiphol airport, both of which are due to go live in 2021. In all honesty, this technology has the breadth and depth to be a global solution.
With the inevitable change in air transport, will Intelligent Approach IA still be relevant?
While there will be changes in the operational patters of transport it is inevitable that air transport will form part of the world transport infrastructure but there will be a focus on value for money and environmental issues. In that respect, Intelligent Approach will aid development by maximizing the use of existing airports with minimal infrastructure investment and maximum focus on fuel saving leading to reduction in CO2. In addition, the capacity gains allow airports the flexibility to grow capacity in their peak and most profitable hours which will help their economic recovery and profitability.
Is the installation process simple and does it require new hardware?
It has always been the intention that IA should be easy to integrate with anyone’s existing systems. As such, the software is modular with standard interfaces for both the data input and the output to the display systems. We can either run it virtually, using a private cloud or physically on two servers. So it is a very small footprint from an engineering perspective. Installation of the application is a simple automated process, which requires very little user interaction.
