A-CDM: Globally interoperable and mutually beneficial

Picture the scene. A Boeing 747 has just arrived at the end of a long journey from Hong Kong or Los Angeles, taxis from the runway to an airport terminal and then is unable to park on its allocated stand. The captain sheepishly comes onto the PA system and announces to passengers that a stand isn’t available – but in fact, there’s still handling equipment on the desired stand left from the previous flight. Or, the stand entry guidance system hasn’t been switched on. Or, the ground crew have been sent to the wrong stand. Passengers are tired and want to get off, the aircraft’s engines are still running and precious minutes in turnaround time are wasted, leading to delays on the return flight, and mounting costs for airlines.

Passengers at Heathrow Airport though, will be enjoying smoother arrivals and departures from this autumn thanks to the introduction of a new initiative at the airport known as Airport Collaborative Decision Making (A-CDM). All airport partners at Heathrow now have access to the same information and a shared view of the airport, the first airport in the UK to implement this, meaning that delays due to lack of communication and coordination will become a thing of the past.

A-CDM is an exciting joint initiative between airlines, ground handlers, NATS and BAA Heathrow. The partners in the scheme work together efficiently and transparently to share data, resulting in everyone at the airport having the same view of the operation. This means that accurate, timely and consistent decisions can be made by all involved in running operations at Heathrow.

Last year, Heathrow passengers faced longer delays than users of other large European airports. Heathrow’s two runways handle around 90 flights an hour, more than any other two runway airport worldwide, and meaning that the airport constantly has to find innovative solutions to a lack of spare capacity. With access to the shared data, air traffic controllers at Heathrow will be able to improve the departure sequencing for flights, saving taxi time, fuel, emissions and money.

On the continent, Munich was the first airport to introduce a similar programme, leading to a 10% drop in taxiing times and con­sequently lower emissions from planes on the ground. Several other airports have already followed suit. Going forward, A-CDM is a key part of the future Eurocontrol Single European Sky ATM Research (SESAR) project and the European air traffic management organisation is enabling implementation of similar schemes throughout European Civil Aviation Con­fer­ence airports.

At Heathrow, we handle over 477,000 flights a year – extremely close to the per­mitted capacity of 480,000 on our existing two runways. This means that any small delay, for example, because of weather related reasons, can have a disproportionately large knock on impact. A-CDM can help in such situations by identifying where potential bottlenecks might occur and allowing the airport to take early action. During times of adverse conditions, A-CDM will become crucial to maximise available remaining capacity, to pass information to partners in anticipation of disruptions (for example, closing a runway for snow sweeping or de-icing) and to help recovery. We want there to be predictability and reliability in operations, otherwise our position is under threat from competitors such as Paris Charles de Gaulle and Frankfurt. Furthermore, Heath­row will benefit in the longer term from more airports becoming A-CDM compliant, which will create a powerful network capability and resilience.

Our experience with A-CDM began back in 2003, and has progressed year on year. Landing times are now displayed within a minute, accuracy has improved, and with this information airlines and ground handling companies are able to adjust their planning accordingly. The whole process is overseen by a steering group, which includes the Airport Operators Committee of airlines, and Airport Users Committee comprising ground handlers, as well as representatives from NATS and BAA.

Earlier this year we completed an upgrade of our own IT systems, and introduced a web based portal designed by American software company Pegasystems. Our portal now pro­vides a situational awareness map of the airfield, and displays information other org­ani­sations have entered about their own pro­cesses, whilst seeing what other airport companies are doing. This allows everyone to see a unified picture of what is going on at the airport. If any part of the turnaround process is going slowly, then alerts can be issued and others concerned with the turnaround can modify their plans accordingly.

For example, an airline can see ‘at-a-glance’ details of stands; planes taxiing around Heathrow; first and last baggage arrival times and crucially, the difference between the estimated and actual arrival times. Our hope is that such a detailed system means that airlines and ground handling companies know best where to deploy resources at any one time and should mean an end to messages from the captain such as ‘we are waiting for a new slot time, air traffic control advise that this should be in 50 minutes time.’

This summer we also introduced a departures element to the software, increasing the efficiency of stand availability. Whilst it might not seem that departures are as important, often stand buffer times mean that aircraft cannot get onto stands quickly enough after the previous plane has left and often stands are not assigned until the last minute. The departures portal reduces the amount of time that needs to be allowed, and means that airport companies can now track the progress of the flight they are handling, from the time when the plane is on final approach, through baggage handling, catering and resupplying the plane, all the way to the point of departure.

The benefits of A-CDM do not end on the ground. Going forwards, we will be able to provide Departure Planning Information (DPI) to Eurocontrol, specifically to their Central Flow Management Unit (CFMU) in Brussels. CFMU will use the information contained in a DPI transmission to manage European airspace more efficiently. Air traffic control slots can be adjusted across Europe, and arrival airports notified if a plane is running late or early on the ground at Heathrow.

At the heart of A-CDM at Heathrow is an in­crease in accuracy in updating departure times. Prior to CDM being introduced, we relied on less accurate estimated off-block times supplied by the airlines or handling agents. This was communicated to CFMU, and a standard 20 minutes taxiing time for Heathrow added. The estimated departure time was too vague and the taxi time too generic – especially when you think of the factors that can affect taxi time. Just a short list could include parking positions, runway in use, aircraft type, push-back method, remote de-icing, traffic density and weather.

Now, A-CDM partners submit a more precise Target Off-Block Time (TOBT). The TOBT represents the time when the aircraft will be prepared, fully boarded and ready to leave the stand. In the next phase of the A-CDM project, the controllers in the Heathrow tower will then assess the airport-wide situation and release a Target Start Up Approval Time (TSAT), which will be passed on to the pilot, flight crew and handlers. This will enable an accurate take off time to be calculated by adding realistic expectations of taxi time to the TSAT. This is the information that is relayed in the DPI message to CFMU, and from there to all of Europe’s air traffic control organisations and airports.

NATS have estimated that under normal operating circumstances, on an average day running with average demand, two minutes taxi time could be saved by using TSATs. At busy times, it is possible that this could be up to five minutes. This helps decrease emissions and noise associated with waiting in the taxiways and holding points.

If all major airports in Europe adopted A-CDM, as an early enabler to the SESAR programme, twice as much airspace capacity could be delivered, with a 10% reduction in environmental impacts and a 50% reduction in costs – all of which is good news for the passengers of Heathrow and across Europe.

This new, exciting scheme is just the beginning. Importantly, we continue to reach out to stakeholders at Heathrow to learn more about A-CDM and encourage them to change their operating procedures to fully incorporate the new techniques. We will continue to develop the software portal to support this. Communication to the myriad partners at Heathrow is key to the success of the project. All the partners at Heathrow are learning together and will help each other to improve their operations as they process these results. With A-CDM, all the airlines and other com­panies at the airport can see exactly where each others’ planes are and what stage of the process they are at. It’s not a case of competition, as if one plane has a delay here that has a knock on effect on the rest of the day’s schedule.

In summary, we will see better use of existing infrastructure (our stands and gates) and reduced congestion. Our airlines will see improved situational awareness and will begin to see improved efficiency and predictability. Air traffic controllers will see improved planning and flexibility. Ground handlers are seeing increased predictability with a reduced amount of activities performed in a hurry. Europe-wide, air traffic demand is better calculated. A-CDM is truly globally interoperable and mutually beneficial to the aviation industry.