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A new airspace for the future

Our airspace has successfully kept the skies safe for more than 70 years. A structured route network, much like roads or railways but in 3D, it allows millions of aircraft to fly through our skies every year. But our airspace is now in urgent need of modernisation.

Why do we need to modernise?

For as long as the flights in UK airspace can be managed safely, modernisation might not seem like a pressing issue. But safety isn’t the problem. Our airspace hasn’t undergone any significant redesign since it was first mapped in the 1950s, but the aircraft flying through it are very different and more efficient – and there are a lot more of them. It was never envisaged that our airspace would need to cope with the volume of flights – over 2.5 million a year – that it does today.

Since 1950, annual air traffic movements in and out of UK skies have increased by more than 1,000%. From the ground, we can’t see the congestion in the skies, so most of us don’t think about the impact it has on our journeys. But the air is no different from the roads we use to travel every day! We would certainly expect delays on the school run, on our daily commute and trips to the supermarket if the number of vehicles on the road increased so much without significant upgrading.

Our airspace is fundamental to the UK economy and for keeping our island nation connected with the rest of the world so it is essential aircraft can fly expeditiously in and out of the UK. To keep aircraft safe, we build in delay when the airspace gets too busy. While today’s flights experience only around 10 seconds of air traffic control delay, it is forecast that by 2030 passengers could face delays of more than 30 minutes .

Even if traffic levels don’t increase as predicted, doing nothing is not an option. Reducing aviation’s impact on the environment is important to NATS and our customers. The proposed changes will end arrival stacking as we know it, enable improvements to continuous climb and descent profiles, shrink the noise footprint on the ground and burn less fuel. Collectively, these improvements will enable carbon emission savings we simply cannot achieve with today’s airspace structure.

How can we ensure that modernisation happens?

Airspace modernisation is now part of Government policy. In December 2018, the Government published its Aviation Strategy, which recognised the need to make flying ‘quicker, quieter and cleaner’. The Civil Aviation Authority’s Airspace Modernisation Strategy maps out the ways, means and ends of modernising our airspace. It sets out who is responsible for delivering change and highlights how aviation stakeholders, such as NATS, will be involved.

Since the publication of the Aviation Strategy, NATS has joined forces with organisations across the aviation industry, including a number of UK airports to launch Our Future Skies, an industry wide campaign which sets out to explain to the wider public why we need to modernise the route network which surrounds and connects our busiest airports.

A new independent body – the Airspace Change Organising Group (ACOG) – has been set up to ensure these vital changes happen.

ACOG will coordinate and support the delivery of transformational airspace change across the whole of the UK, bringing together the work of all the airports, which are responsible for changes to their departure and arrival routes up to about 7,000ft, and the higher-level network that they connect with, which is the responsibility of NATS. It includes some of the most complex airspace in the world, in South East England, as well as the airports supporting the growing economies of northern England, Wales and Scotland.

As well as the commercial aviation industry, it also draws in airspace users including the Military, who have large training areas all around the country, and General Aviation which includes both leisure and training activities.

Airspace in the South, including upper en-route traffic across England and Wales and low-level traffic around London and the South East, is managed by NATS’ Swanwick Control Centre in Hampshire. Traffic across Northern England, Scotland, Northern Ireland and over the North East Atlantic is managed by the Prestwick Control Centre, in Ayrshire.

What does 'modernising' airspace mean?

It means making our skies work more efficiently. One of the ways we can do this is to increase the systemisation of our airspace, reducing the need for interactions between aircraft and air traffic control. New technology at our control centres will enable this automation and allow controllers to safely manage more aircraft.

Improvements to the route network itself are vitally important to allow this increased systemisation. New technologies won’t realise their potential if they are deployed on an old network. New procedures will cover all phases of flight from take-off to landing and the introduction of a greater number of defined routes between airfields and the point aircraft exit, or enter, UK airspace. We have already deployed new technologies which help us manage aircraft arrival times while they are still hundreds of miles away from landing, which is saving many minutes wasted queueing in a holding stack to land. Further development of our queue management techniques will end stacking as we know it today.

Many of the changes rely on using performance-based navigation standards (PBN). PBN is a modern aircraft satellite-based navigation system which allows aircraft to follow a route with precision and consistency. It allows us to make the most of today’s aircraft capability as well as reducing risk of delay by moving away from using legacy airspace structures which relied on ground-based navigational aids. Making the most of PBN also allows better management of noise for people who live near airports, as more routes can be designed in, which means they can be alternated to provide respite.

Improvements to our network design

Airspace modernisation is essential across the UK. However, the Government recognises that there is a particular need in South East England, where many of our busiest airports are concentrated. The London Airspace Modernisation Project (LAMP) will modernise the airspace structure over this area, introducing a complete redesign of the network above 7,000ft This new design will ensure the growing number of aircraft can be safely accommodated and will make flights more efficient to minimise environmental impact.

LAMP will be supported by the Swanwick Airspace Improvement Project (SAIP), which is already reducing the complexity of high-level operations over southern and central England by better managing traffic flows. This has been done by introducing new, and making better use of already existing, PBN routes.

Further north, the Prestwick Lower Airspace Systemisation Project (PLAS) will make changes to airspace covering the Manchester, Scottish and Belfast Terminal Control Areas as well as the airspace over the Irish Sea. Changes will include introducing standardised arrival and departure routes to reduce dependency on ground-based infrastructure. These routes will allow aircraft to follow designated routes between the runway and wider network.

Enhancing arrivals management

Improving how we manage arrivals is essential in order to modernise airspace. Continuous climb and descent operations will enable us to better manage noise for people near airports. These techniques will deliver environmental and economic benefits without compromising of modern aircraft. They are not new – in fact, they have been used successfully for decades – but at busy airports, they are not always achievable and there is always room for improvement.

If you’ve ever flown from Heathrow Airport, you will know that after take-off, you climb and then level off for a while before the engines surge again and you continue climbing to your cruise level. That level off is at about 6,000 feet and it’s because you are passing underneath an arrival holding stack, the base of which is at 7,000 feet.

Holding stacks are used at many of our busiest airports like waiting rooms for aircraft. Aircraft enter at the top of a stack and spiral down until they are directed onto final approach. Interestingly, stacking is not a symptom of inefficiency – the oversupply is an efficient way of making maximum use of landing slots at airports where arrivals can be scheduled to 99% capacity.

But they’re not a perfect solution. They are certainly not efficient - they burn more fuel and create more carbon emissions than they need to, and are noisy for the people who live beneath them. If we move the holding stack away, your departing flight will be able to climb straight to cruise level, burning less fuel and reducing its noise footprint on the ground.

Ongoing work to develop an arrival streaming capability will also reduce today’s reliance on holding stacks. Even with the most efficient network design, the ability to effectively manage arrival flows is limited without working with other air navigation service providers (ANSPs). Cross-border queue management makes it possible for controllers to ask the ANSPs responsible for the airspace which surrounds the UK, for example France and The Netherlands, to slow aircraft down when delay is predicted. This allows delays to be absorbed enroute, before aircraft enter UK airspace, rather than waiting to land in holding stacks.

This approach to queue management is fully operational at Heathrow and Gatwick Airports, with Heathrow offering a 350 nautical mile operational horizon, the largest for extended arrivals management in Europe.

Where are we now?

We’re using the latest in airspace design methodology to help us redesign airspace structures across the UK, working closely with airports to connect low-level designs. NATS is in an excellent position to redesign the airspace, having extensive experience as an air navigation service provider (ANSP) and access to a wealth of data.

We are currently working towards creating initial designs for our future airspace, which we will be consulting on. Check back for more information soon.

References

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/586871/upgrading-uk-airspace-strategic-rationale.pdf (page 7)