When a man faces the prospect of his imminent execution, said Samuel Johnson, his mind concentrates wonderfully. Although quoting someone who was originally referring to capital punishment might seem extreme, try telling that to Heathrow’s air traffic control personnel.

Working in Europe’s busiest airport involves a deft concatenation of talents as teams work round the clock to deliver a seamless flow of arrivals and departures in and out of the hub’s five terminals – unless, of course, they wish to see a horde of irate holidaymakers descend upon the control tower.

Essentially, says Jon Proudlove, this has been the pattern of operations at Heathrow Airport for the past ten years. In his capacity as the general manager for the National Air Traffic Control Service (Nats), the company contracted by Heathrow to manage its air traffic services, Proudlove is accountable to the airport for making sure that the flow of arrivals and departures is as seamless as it could possibly be.

"These are two of the busiest strips of concrete anywhere in the world, and about 99% of our available capacity is declared and used on a daily basis," he says. "While other airports have the luxury of having headroom and resilience within their operations, that’s not the case with Heathrow. Any kind of perturbation to the schedule leads to a disrupted day. Here, every second counts."

Fine margins

Yet, despite these pressures, air traffic control at Heathrow has managed to squeeze another flight in. Since March, Vietnam Airlines has occupied the first new slot on the airport’s roster since 1996. For such an oversubscribed hub, that’s the equivalent of finding £50 stuffed down the back of the sofa, and it’s all down to Heathrow’s incorporation of the Strategic ACM software into its flight-planning regime.

At its core, ACM is nothing more than a simulator. Flight personnel at Heathrow feed information on the daily pattern of arrivals and departures into an in-built database, and they then rely on the program to make scheduling projections as to what the typical state of affairs at the airport might look like in a week, month or year’s time.

On the face of it, making new decisions based on old information seems little different to how Heathrow previously managed its scheduling regime, but Mark Burgess begs to differ. As head of air traffic management and flight performance for the airport, he is adamant that ACM has allowed Heathrow to find space in its schedule it never knew it had.

"What we wanted and what we got in the system was the ability to do things far quicker, and in a more intelligent way that allows much more time to be used focusing on the analysis and the decision-making," he says.

That process not only involves the creation of new capacity, but the quick adaptation of the schedule to the changes individual carriers want to make to their own arrivals and departures as well.

"The airlines fine-tune their schedule," explains Burgess. "There is a core schedule that we agree with the carriers based off of their wish lists, but within that, there’s an awful lot of movement. They’re looking at leaving five minutes on one side or five minutes on another, which in itself doesn’t sound significant; at an airport like Heathrow, however, that can impact the schedule dramatically."

This is largely down to the management of spacing between aircraft on the runway. For example, a large plane like a Boeing 767 will require a set amount of time in which to land and taxi, while a smaller aircraft like a Learjet will need be spaced further behind. Pinpointing the time between when these planes will take off and land is the key to either maintaining an efficient schedule or seeing the notification boards within Heathrow’s five terminals light up with news of delays or cancellations.

For years, staff at Heathrow achieved this by making complex mathematical projections of a day’s schedule several months in advance. However, the addition of Strategic ACM has allowed the ATC department to more effectively reconcile the capacity limits of the airport with the desires of the carriers by letting them see the impact of their suggested alterations within hours. It’s a world away from the previous system.

"Before we had the software, the whole runway-scheduling process at Heathrow could take anywhere up to two to three months of meetings with airline stakeholders," says Proudlove. "The whole process now basically involves one day of the airlines gathering at Heathrow, submitting their wish lists and our running up to dozens more scenarios that can better explore the full implications on the airport of what these companies are asking for."

Full speed ahead

Use of the program has also prepared Heathrow for the possibility of planning even further ahead than previously thought possible.

"We’re very much at the start of our journey with ACM," says Burgess. "At the moment, we’re involved in what we call strategic capacity planning, still a matter of months before the date of operation. Now, we’ve moving into the margin of a matter of days – what we like to call ‘pre-planning’. That takes into account data like weather forecasts and predicts, in a short period of time, how that is going to affect the scheduling. We’re working very closely with Nats on what a real-time operation will look like."

That’s thanks to the capabilities of ACM’s historical scheduling database. The more data is uploaded, the more complex and accurate the projections. "Previously, we were only able to base our decision-making on a very small set of study days," says Proudlove. "Now that we have a platform that is loaded with new data every day, we have a significant list of precedents upon which to base our decision-making. We can now more easily schedule for what we think might be a foggy day or a very windy day."

It’s made Proudlove hopeful that the lessons learnt at Heathrow could easily be applied to other hubs. "Given that it’s been demonstrated that the ACM tool can be successfully deployed at Heathrow, then it absolutely could be used at other airports," he says. "At that point, you’d need to be loading the local rules and variances that you see at those airports into the platform, but it certainly has demonstrated its capability."

"And the message we’ve had sent back to us from numerous airlines operating out of Heathrow is that they are really buying into the changes that we’re making in the schedule from the way the new analysis is conducted," adds Burgess. "It’s allowing them greater flexibility in their operations that we wouldn’t be able to give them without the capabilities provided by ACM."

Finite resource

Ultimately, though, no matter how effective ACM is in finding space in the schedule for extra flights, it remains a palliative measure. Two factors continue to maintain that impenetrable ceiling on Heathrow’s capacity, one of which is the lack of available coordination with their colleagues in Europe.

"It’s interesting that the future need of a single European sky is already needed at Heathrow as soon as possible," says Proudlove. "This is really the whole reason why we’re pushing the boundaries of technology and capability with ACM."

The other, unsurprisingly, is the lack of capacity in the schedule that spurred the adoption of ACM in the first place. At one of the busiest airports in the world, the lack of a third runway is becoming intolerable, at least among its staff. While Sir Howard Davies, the chair of the independent Airports Commission assigned by the government to find a viable solution to Heathrow’s capacity problems, has recommended its construction, there is still a long way to go before this might be enacted, never mind opened.

The situation recalls Johnson’s adage on mortal deadlines: although Heathrow has concentrated its mind wonderfully, and will continue to do so for some time yet, some form of denouement is inevitable.

"We’re operating at 98% capacity already, and we’ve been doing that for the past decade," says Burgess. "Despite that, we are continuing to increase traffic. In 2014, we had something close to 73.4 million passengers use Heathrow’s facilities. That was our busiest ever year, and that number is set to grow even more through the use of thinner and bigger aircraft. Yet the fact remains that our capacity, in the end, is limited."