EXCDS Waving goodbye to paper strips: managing the end of an era in Europe’s busiest airspace

A radar screen. A headset. A telephone. Paper. A pen. For the past 60 years or so, these have been the core tools air traffic controllers in the UK have relied on to keep the skies safe and aircraft moving. But, as of earlier this year, two of those tools gradually disappeared from the last of our control rooms– the London Terminal Control Centre at our Swanwick Operations Centre.

Pete Dawson, General Manager of Swanwick Operations explains: “It might seem hard to believe, given how busy our skies are, but pen and paper have been an essential part of a controller’s tool kit right up until the last few months”.

“They’ve been the primary means by which Controllers record the instructions provided to a pilot and track a flight’s progress as it transits through the UK’s airspace. Altitude, heading, speed – all of this has been manually recorded on a printed flight strip. Until now, that is.”

Over the first half of 2018, the London Terminal Control Centre, which manages the traffic in to and out of London’s five international airports and across the South East of England, retired its pens and replaced them with an electronic system called EXCDS, developed and used by our friends across the water, NAV CANADA.

The need for change

When we talk about busy skies, we are talking about more than 2.5 million flights passing through the UK every year. Only the United States and China have a larger aviation network than the UK, an incredible fact really given the size of airspace managed by the UK compared to many others.

“More than 370 destinations are served from our relatively small island”, explains Pete Dawson. “And traffic records are being broken almost week by week, with winter months – traditionally a quieter time for air travel –now feeling like summer months did a few years ago.

In 2017, we handled more than 2.5 million flights. Of those, almost 51% entered or left one of the airports managed by controllers at our London Terminal Control Centre.”

Keeping track of the instructions given to a pilot is a fundamental part of air traffic management. Whilst work is already underway on more advanced systems that will connect with aircraft and automatically record aircraft movements and trajectories, recording that information manually has always been an essential part of safely and efficiently managing our busy skies.

For every flight, a paper strip could have up to 10 instructions written on it. In addition, controllers might have to make up to four calls to each other to coordinate that flight as it passes through the airspace en route to its destination. All of this adds to a controller’s workload and helps define total airspace capacity, which is in part a direct result of the volume of aircraft they can be ‘working’ at any one time.

ExCDS will provide our controllers with automated flight data management information via new touch-screen controls installed in the operation. However, while it automates some processes and reduces the need for manual coordination between controllers working in different positions, it will still rely on controllers to manually input much of the information they currently write on paper strips about the instructions they’ve given to an aircraft. This increased electronic coordination is essential in order to help controllers to manage with the ever-increasing demands on the UK’s congested skies."

- Chris Edwards, Transition Manager for London Terminal Control and a former TC Air Traffic Controller

Preparing for change

Preparing controllers for a change of this sort is a huge undertaking that requires years of planning and engagement – with controllers, engineers, training teams, software manufacturers, our airline and airport customers, the regulator, the Government and more. Airspace is a critical piece of infrastructure but it’s also invisible to most, with everyone generally expecting it to be ‘open’ and functioning at full capacity 24 hours a day, 7 days a week, 365 days a year. This presents a huge challenge when working out how to plan for a significant change like this.

“Balancing the need to take controllers out of the operations room for training alongside the need to manage record levels of traffic is really tricky”, explains Chris Edwards. “We need to ensure controllers have had sufficient training such that when they come to use the new system in a live operational environment, they’re confident and able to safely handle real-life volumes of traffic. However, training requires controllers to have time outside of the operations room, but we have to balance that with the need to have sufficient numbers working the skies in order to keep people moving.”

Preparing controllers for a change like this is vital. Paper strips have been used in air traffic control since its origin, and the way controllers interact with and manage their paper strips is deeply ingrained in the way they think at a subconscious level, and even in their fine motor movements.

”Close collaboration between the teams through the early feasibility and definition phases allowed us at NAV CANADA to understand NATS’ high-level requirements to ensure EXCDS met their unique needs. From Ottawa, we then made all the software updates to satisfy NATS’ human-machine interface requirements (the part of EXCDS that controllers interact with).”

- Stephan Radatus, Manager, ATC Commercial Systems Engineering, NAV CANADA

Whilst using digital interfaces for task management is unlikely to be a particular challenge for many, using them in a fast-paced, safety-critical environment is a different matter. This is where the work of Human Factors specialists comes in. They worked alongside the controllers and NAV CANADA to ensure that the system that went in to the London Terminal Control Centre suited that specific team and operational environment.

“Extensive user testing and structured safety assessments enabled us to understand how the controllers would use EXCDS in real-life scenarios”, explains Lisa Aldridge, Senior Human Factors Specialist at NATS. “This showed us where the HMI needed refining to ensure the tool was clutter free and fast enough for controllers to use.”

Making sure controllers were involved in the development of the tool was key to securing the support of the operational community.

Learning from past experience

Pete Dawson explains: “There had been previous attempts to introduce an electronic flight system in to London Terminal Control in the past but, for a variety of reasons, it had never been seen through. Making sure that controllers were involved in the planning and development phase of the project, as well as in shaping the final design of the system, was a really important part of the process.”

To this end, a core team was set up with controllers at the heart of it. Al Hambly, a terminal controller with 18 years’ experience, acted as the lead controller on the project team. It was his role to engage with his colleagues, listen to their feedback and feed it in to the design team to ensure the changes required were being reflected.

“The design process was very challenging as paper and pen operations were extremely versatile and intuitive for the user, speed of data entry and overall situational awareness were specific concerns we needed to address. Although some aspects of the design were less efficient than paper strips, new capabilities such as electronic coordination and automatic strip distribution more than made up for the shortfalls. People were naturally resistant to this level of change, but now they have had a chance to consolidate, the majority of users would never go back.”

Getting the tool right and the controllers prepared for its introduction was a vitally important part of the project. But internal preparations were only one element of planning for an effective transition; the other was engaging with external partners – particularly our airline and airport customers.

Collaborating for change: an industry-wide approach

Airlines are never going to like it if you tell them there are going to be delays, understandably, but they like it even less if you tell them there aren’t going to be delays and then there are"

- Andrew Burke, Customer Affairs Manager at NATS

“Introducing a new system like this is not something we can or would want to do in isolation”, explains Pete Dawson. “One of the things we had to do in the early stages of the project was to think about how we’d introduce this new system, what the likely impact would be on our customers and their passengers , and to then think about how we could minimise that impact as much as possible.”

One of the first decisions taken was to engage the airlines at a really early stage of the planning phase, more than 18 months in fact before the first deployment. This provided a chance to bring our customers into the planning process: “To explain why we were making the change – the rationale for introducing the new system, to brief on what we thought some of the challenges might be along the way, and to discuss possible ways we could work together to mitigate any potential disruption”, adds Dawson.

The introduction of iTEC, a separate but equally significant system used by Area Controllers, at our Prestwick Centre in 2016, had caused some unforeseen delays. The fact that this delay hadn’t been predicted made it harder for airlines to plan in advance and to mitigate the impact on their operations. “We were determined to learn the lessons from that experience”, adds Andrew Burke, “and to make sure the airlines were as involved in the planning process as they could be”.

He continues: “We wanted to have a really open, honest and mature conversation with our customers that briefed them on what was coming and to make sure they were engaged and felt part of the transition process. At the end of the day, they are our customers and the services we provide are there to enable them to transport their customers – the flying public – safely through the UK’s busy skies”.

One element of this engagement was the plan for deploying the system in to the operation. A critical part in planning for the safe introduction of EXCDS was to recognise that, despite all the training that controllers could undertake on the tool outside of the operations room, nothing can quite replicate its use in real live operations.

To recognise this, a transition plan was devised that would both provide controllers with the safety net to grow confidence using the tool in a safe way, whilst also minimising the disruption across the operation.

Chris Norsworthy, who headed the deployment of EXCDS and helped devise the transition plan: “Our Human Factors team determined that controllers using EXCDS should begin to do so managing only 80% of the traffic they would normally manage. This was deemed a safe level at which controllers would be able to safely manage the traffic levels using EXCDS in their initial few days, with the traffic levels gradually increasing first up to 90% after 10 days and then back to 100% after 20 days.”

Whilst these might sound like modest reductions, a 20% cut in traffic across the entire London Terminal Control operation would have a significant impact – causing major delays and possibly even cancellations.

“We had to find a way to avoid that scenario”, explains Norsworthy. The way this was achieved was to devise a staged transition, which broke the London Terminal Control operation down in to five sector groupings. Splitting the operation into five sector groupings gave us a few benefits. Firstly, it meant that only one fifth of the operation was operating at 80% capacity at any one time – four fifths were still at 100% capacity."

“Secondly, it meant that as the transitions went on, some controllers who were validated on more than one sector – which many are – had some operational experience using the tool already, which meant that they had greater confidence and could share their experience with their colleagues.

“Thirdly, it meant that feedback could be collected from each sector grouping, which tended to have similar characteristics. This meant feedback could be gathered as to how the tool was enabling controllers to manage specific operational characteristics unique to each sector. And finally, it meant that those sectors that weren’t going through their transition could, where capacity allowed, manage additional traffic, so aircraft that would normally have passed through the sector transitioning to EXCDS instead re-routed through a neighbouring sector.”

This is where collaboration with the airports and airlines really delivered benefit, both in advance of the transition and during it. Being open and transparent with our customers allowed them to plan and mitigate any impact of their passengers. We worked with them to develop plans for managing the flows of traffic flying through those sectors during the initial phases of each transition in order to minimise disruption to the flying public. During the initial days of each transition, we also had representatives from the airlines most likely to be affected at our operations centre so that they could keep up to date with each transition and communicate any operational decisions.

Geoff Kingston, Flight Planning Manager at easyJet welcomed NATS approach to the transition: “NATS were very honest with the delay modelling and what those delays would look like. It allowed us to sit down together and look at how we could manage those delays.”

He added, “in terms of involvement of the customer, we have to praise what NATS have done. The difference with ExCDS was that from day one that planning was happening collaboratively between airlines and NATS.”

But it wasn’t just the airlines which were integral to the process.

Wendy Howard-Allen, who led much of the detailed engagement with the airports and airlines on the transition plans, explains: “Working closely with the airlines, though vital, wasn’t enough on its own. We recognised that a transition like this required collaboration right across the industry and we also worked closely with our colleagues at the airports involved in each transition. This helped us to understand their particular challenges, the potential impact different scenarios for managing the reduced traffic flows would have on them and, through conversations with them and their airline customers, how best to mitigate the negative impact.”

Another element that was seen as vital to the engagement plan in advance of the transitions was how messages reached the public. One way to do this was via the media. We invited the media to visit and see first hand what was to be changed and how we would go about doing it – and we were honest with them about possible delays so they could help explain to the travelling public what the impact might be and why we were doing it.

This went hand in hand with the engagement with the airports and airlines, who of course have a more direct relationship and more direct communication with the flying public. Those airlines and airports were then able to use the information they had to either brief their passengers and customers directly and in advance of travel if they felt it necessary, and to brief their pilots so they could explain why there was a delay if one was experienced on the day. Whilst none of this of course reduced the duration of the delays experienced, it did at least mean that those unfortunately impacted by the transitions were more likely to have it explained to them why and that everything was being done to mitigate any negative impact.

A foundation for the future

With the five transitions now complete, EXCDS is fully operational and providing the benefits we envisaged.

Pete Dawson adds: “We’re proud of how our controllers, engineers, training teams, NAV CANADA and our airline and airport customers worked together to deliver EXCDS.

Delivering change in any industry is never easy, perhaps more so in a safety critical 24/7 environment but with growth expected over the coming years we can’t rely on the technologies of the past. We need to make changes and update the tools we use and the route network to ensure that people can get to where they want to fly, in a safe and timely manner.”

Whilst no-one likes hearing there are going to be delays, the reality is that making changes to a system that is expected to be active 24/7, 365 days a year requires some compromises. The EXCDS transition showed that collaboratively, we can do a lot to try and mitigate the impact. It doesn’t mean there won’t be delays, and we always regret any disruption that is caused to our customers and the flying public, but it does show that by working together, closely and openly, we can make the changes we need to make to ensure the UK has the airspace infrastructure it needs for the years ahead.

Over the coming years we have a significant programme of change to deliver that infrastructure to meet the traffic growth that is forecast. EXCDS was one step on that journey and shows that by working together we can deliver the air traffic management environment we need for the future.

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