Copenhagen’s new tower: advanced solutions to exceptional challenges

When in 1716, the Danish Empress Katharina drove up to the top of the Round Tower at Copenhagen’s Trinitatis church in a horse-drawn carriage with her husband Peter the Great, she set a certain precedent in remarkable tower transport operations. But 291 years later the tradition has been maintained, when one of the world’s most advanced airport ATC towers came into operation on time, on budget and with all systems working as specified.

The new Copenhagen/Kastrup tower came on-line at 1am on 29 December 2007 as part of a 50-programme upgrade of Denmark’s entire air traffic management (ATM) system called DATMAS, the Danish Air Traffic Management System. As well as the Copenhagen/Kastrup tower, DATMAS incorporates a new en-route and approach control centre and new tower/approach systems for Billund and Roskilde airports.

Traffic is growing steadily at Kastrup; despite the cancellation of many hundreds of SAS Dash Q400 flights in November as a result of landing gear problems. The airport handled 21,409,526 passengers in 2007, an increase of 2.5% over 2006. The old control tower was built in 1971 and at just 36 metres was struggling to give controllers the full 360 degree view of the airfield; a complete view of traffic on runway 22L, for example, was not always possible.

Copenhagen/Kastrup is the largest intercontinental hub for SAS and long-term trends point to even higher rises in passenger and aircraft numbers. For this reason, the decision was taken in 2001 to replace the old ATC control tower and separate ramp operations facility with a single new structure, equipped with advanced ATM systems, to give the airport the necessary improvements in safety, capacity and efficiency for the foreseeable future.

Airport towers offer a unique series of challenges for transport planners and for the Copenhagen facility the challenges were particularly interesting.

First was the problem of height. The ideal is to go as high as possible to give controllers the best possible view of the airfield, covering 12 square kilometres from Kastrup in the north, to Dragør in the south. At Copenhagen/Kastrup the tower is close to the sea and with stratus clouds scudding in low over the waves, it took some time to find the optimum level for the control room. “The way we did it was take controllers up in a helicopter, to look at the airfield layout from different levels to ensure we had an interrupted view without having to go too high”, said Lars Bech Madsen, Deputy Director General of Operations at Naviair, Denmark’s air navigation service provider (ANSP) and the organisation responsible for specifying and managing the entire DATMAS programme.

“One of our biggest challenges was to make sure that the air traffic controllers working in the tower don’t get seasick. That is a major problem in several of our neighbouring countries. However, we have tested the tower thoroughly, and it will provide air traffic controllers with the best possible view, but it won’t make them seasick,” said Halldor Ragnarsson from building contractors E. Pihl & Søn. The stabilisation operation was achieved with the addition of 50 tonnes of steel plates to the top of the structure, to ensure that the frequency of the building’s movement in the wind was well within the safety margins.

Then there was the challenge of materials. Kastrup is a constrained airport, which means the amount of metal on the outside of the structure had to be kept to an absolute minimum, as it could have interfered with the ILS signals. This was a particular challenge when it came to providing the right ambient light for controllers looking on to the airport apron through the huge windows. Instead of using metal materials within the glass, to provide the optimal shading levels, the tower features 80 blinds, with a computer-controlled pre-selected management system to ensure the correct ambient light levels at all times. “We computerised the system because we didn’t want controllers spending all their time raising and lowering the blinds to achieve the optimum light levels,” said Lars Bech Madsen.

Naviair is responsible for all aircraft movements in the airport, while the airport operates the gates. It was also a challenge to integrate the airport and ATC systems within a single space, because the responsibility of equipment is split between Naviair and the airport. The airport operates the ground movements radar, navaids, metrological equipment and runway lights, while Naviair operates all ATC equipment.

The new tower was designed from the start to integrate these separate operations within a combined control room. This has been built on two levels, with ATC operations on the upper level and apron ground control below. There is now a total of 240 square metres of space for all controllers – a considerable increase over the former facilities.

The heart of the tower operation is the integrated suite of ATC systems, which make the Kastrup/Copenhagen tower one of the most advanced of its kind in the world. While architecturally an airport tower is a landmark for the airport and the ANSP, it is the systems inside which really define how successful the infrastructure providers will be in delivering the new safety, capacity and efficiency improvements required for the future. Airports are now recognised as being probably the most important bottleneck to future aviation growth within Europe – so the success of an airport tower in maximising the airport’s limited capacity has crucial continental, as well as national, implications.

Our main challenge was to produce a system which would meet the needs of controllers, but which could also be delivered by the contractor.

The key question facing any organisation looking to replace its legacy ATM systems is: how far should innovation be pushed? After all, a new generation of ATM tools based on exciting technologies such as ADS-B, data-link and internet protocols, offer major potential improvements in surveillance, navigation and communications capabilities and efficiency levels. The last decade of the twentieth century, within the ATM community, was notable for the impressive number of ambitious systems replacement programmes, which came in many years late and many millions of dollars over budget.

“In the old ATC tower we had many different systems running on separate screens, each from different suppliers,” said Lars Bech Madsen. “We needed to integrate many of the separate functions so we could see, for example, the status of the runway lights and the ground movement radar on the same screen.”

Identifying aircraft and airport vehicle movements, identities and intent, is particularly challenging at Kastrup because of the complex and constrained arrangement of runways, taxiways and apron areas.

“Kastrup is a relatively small airfield but with a high number of operations,” said Bent Fog, Naviair’s Director, Technical Maintenance. “The apron area is close to the crossing runway, there’s not much space and the taxiing area is complex and crowded. Over the last few years we have gone from three traffic peaks a day to five.”

The airport’s two main parallel runways, feature approaches and departures over the sea. When a cross wind picks up speed and intensity (as it does seven or eight days a year, on average) aircraft are switched to the single crossing runway, which takes them directly over the city centre and reduces the airport’s take-off and landing capacity by around 50%.

The operating philosophy behind the tower systems has therefore been to specify and integrate the most advanced technologies available – but only if they have already been successfully implemented elsewhere. Each ATC controller’s work-station comprises a DATMAS ATM radar display, a combined ground movement radar and airfield lighting display, a Naviair Integrated Tower Operation System (NITOS) which automates the coordination of flight data movements between runways, taxiways, terminals and apron and is integrated with the airport’s own automated systems, a voice communications system based on Park Air digital radio technology and an advanced airfield information system.

Within the ATC tower room there are five available workstations (with the different displays based on height movable tables), of which three are operated at any one time.

The core DATMAS technology is based on a Thales system, which has been recently supplied to Sweden and Ireland. Controllers and experts from these countries were an integral part of the process of fine-tuning the system.

The NITOS airfield flight data processing system is based on a NAV CANADA tower system, which has recently been installed in Canadian airports and at London’s three busiest hubs. One of the characteristics of the system is the replacement of paper flight data strips with electronic touch-sensitive display screens. According to NAV CANADA: “This significantly reduces the need for voice communications among controllers and replaces the traditional method of using paper strips to keep track of air traffic. It increases efficiency by ensuring an instantaneous sharing of relevant flight information between workstations within the tower, and between the tower, airport and terminal control, permitting more efficient management and use of airspace and airport capacity.”

Implementing NITOS at Copenhagen has been another formidable challenge – especially as the schedule from contract award to operation was a very tight two years.

The new tower systems first became operational in October 2007, “shadowing” the systems in the old towers. At the start of 2008 the process of ramping up DATMAS operations to 100% capacity began and full operating status is planned for the start of April.

Reference

1. Source: http://klr.dk/CPH/UK/Newsroom/ News/2004/A+landmark.htm

About the author

Morten Dambæk was born on 28 May 1952. He achieved a Masters in Law from the University of Copenhagen and has worked in the aviation industry since 1978 when he was a Legal Advisor with the Danish Civil Aviation Administration (DCAA). Since then he has held several positions within the DCAA, including; Director of Air Transport, Deputy Director General with responsibility for Safety Regulation and Deputy Director General with responsibility for Air Navigation Services. In August 2001 he was appointed Director General of Naviair. Mr Dambæk is also new chairman of the EC3 (European CANSO CEO Committee).