Controlling Sydney: every second counts

As the country’s air navigation service provider, Airservices Australia is working closely with the airport, airlines, operators and the community to achieve operational and environmental efficiencies using the existing infrastructure. Airservices is also introducing new airborne and ground-based systems to handle predicted future growth of air traffic at the airport.

Considered as the gateway to Australia, Sydney Airport is the country’s busiest in terms of total passenger numbers and aircraft movements. Air traffic controllers handled 309,918 movements, equating to almost 36 million passengers passing through the airport’s international and domestic terminals during the 2010-11 financial year.

On the shores of Botany Bay, approximately eight kilometres south of the city’s central business district, the airport is closely scrutinised by the community it services. The airport’s three runways are restricted by a curfew (between 11pm and 6am) designed to provide noise amelioration to a population of four million in the greater Sydney area. All bar two current flight paths track over heavily populated urban areas.

A typical Sydney day can involve around 900 aircraft movements and at times demand reaches the capacity of a capped (by Federal legislation) 80 movements per hour, particularly when poor weather sets in.

Airservices has a number of new technologies, systems and management procedures in use, or poised for introduction, at Sydney to maximise movement efficiencies, while at the same time working to reduce the burden of aircraft noise on the community. These include a Precision Runway Monitor (PRM), Wide Area Multilateration (WAM), Advanced Surface Movement Guidance and Control System (A-SMGCS), Ground Based Augmentation System (GBAS), Collaborative Decision Making (CDM) program and the Long Term Operating Plan (LTOP).

The airport’s two parallel north-south orientated runways (16L/34R and 16R/34L) handle the majority of movements annually. Designed to provide safe and practical parallel runway operations when weather conditions prevent independent visual approaches, the PRM is a highly accurate surveillance system that allows qualified pilots to accept reductions in lateral separation standards during an instrument landing system (ILS) approach.

At the heart of the system is a high resolution radar providing a very fast update rate for display to a specialist PRM controller monitoring each approach. A 'No Transgression Zone' (NTZ) with a width of 610 metres/2,000 feet is established between the parallel approach paths to provide a suitable safety buffer between aircraft on adjacent ILS approaches.

Using PRM, aircraft can be processed independently of any traffic on the adjacent approach track, whereas air traffic control would otherwise apply a 2 nautical mile staggered separation between aircraft on parallel ILS approaches. The PRM is vital in maintaining airport capacity and reduces air traffic delays by as much as 80 per cent in poor weather.

The recent introduction of wide area multilateration (WAM) at Sydney will ultimately replace PRM. WAM is an extension of the multilateration technology currently being introduced as part of the advanced surface movement guidance and control system (A-SMGCS). In addition to supporting independent parallel runway operations in instrument metrological conditions, WAM will also provide a backup to secondary surveillance radar.

The introduction of A-SMGCS in May 2010 gives surface movement controllers in Sydney Tower the ability see and identify every aircraft and vehicle across all runways and taxiways. The A-SMGCS program improves situational awareness by providing a ‘radar-like’ picture of what is happening on the ground on a screen in front of the surface movement controller in the tower cab.

Distances from the tower can make visual monitoring more challenging, particularly during bad weather and at night. A-SMGCS, through the collection of surveillance data from multiple sources including surface movement radar, multilateration, Automatic Dependant Surveillance Broadcast (ADS-B) and terminal area radar, offers better conflict detection for controllers while improving the reliability and efficiency of airport operations.

Airservices is in the final phases of evaluating the use of a satellite-based precision approach and landing system at Sydney Airport as a future replacement of ILS. The Ground Based Augmentation System (GBAS) is a critical component of Australia's next-generation air traffic management infrastructure and will help better manage airport delays, aircraft fuel burn and noise.

On 23 November 2006, a Qantas 737-800 conducted the world’s first GLS (GNSS Landing System) approach, under visual conditions, at Sydney using a prototype GBAS. Since then the airline has flown more than 2,500 GBAS-supported approaches and trained over 700 pilots on GBAS operations. Pilots have consistently reported that GBAS provides extremely smooth and stable guidance and in coming years over 50 per cent of Qantas’ aircraft fleet will have GBAS capabilities installed.

Earlier this year, the first production GBAS to receive Federal Aviation Administration system design approval, the Honeywell SLS-4000 precision landing system, was installed at Sydney. Acceptance testing of the new system was carried out in August prior to a three-month test and evaluation period due to commence in November. Airservices will then apply to the Civil Aviation Safety Authority to have GBAS Category I (CAT-I) operations approved for use at Sydney during the first half 2012.

Airservices is also developing tools for the Collaborative Decision Making (CDM) program at Sydney and at other capital airports. CDM has the potential to improve air traffic management through improved sharing of information and data between airlines, airport operators, ground handlers and air traffic control. CDM can be applied to all air traffic management processes, from long-range schedule planning to tactical decisions related to ground delay programs.

This exchange of information will allow all users to be aware of constraints, issues and the needs of other industry stakeholders with the overall goal to create a more knowledgeable and participative aviation community. CDM partners can participate to a level that suits their operations and information requirements. However, in order to maximise the benefits users are encouraged to participate in the sharing of information.

The first stage of CDM sees the replacement of Airservices Central Traffic Management System (CTMS) with a new advanced system capable of managing pre-tactical air traffic flows at multiple airports simultaneously. The Metron Traffic Flow (MTF) system is scheduled for implementation at Sydney in late November. The MTF will provide significant benefits such as reduced airborne holding, and consequently reduced fuel burn and environmental emissions.

Critical to the efficient operation of the national airspace system and managing the impact of aviation on the environment, the steps taken to increase efficiency using all of these processes will be in harmony with current Australian standards and practices, while providing sufficient room for the development of local procedures. While every movement matters and every second counts, over many movements the seconds add up to create additional capacity that in turn can reduce delays and offer more capacity.

Airspace usage takes into account the effect of aircraft noise on the community. Sydney Airport has had a unique framework in place for noise sharing since 1996. The Long Term Operating Plan (LTOP) for the airport aims to ensure as many flights as possible operate over Botany Bay or non-residential areas. When this is not possible, for weather or other operation-related issues, LTOP is designed to share the noise burden of aircraft over residential areas as equitably as possible. Airservices reports to the community on its compliance against the plan quarterly, with detailed reports published on their website.

Under the LTOP there are up to 16 different runway configurations, or modes, which are available to share noise around the community. LTOP targets include the majority of aircraft movements, some 55 per cent, operating to the south over water, with 17 per cent of movements to the north, 15 per cent to the west and 13 per cent to the east. Constricted by wind conditions, Airservices uses LTOP as part of its daily operating procedures and can mean up to four mode or runways changes throughout a day’s operations.

The architecturally iconic control tower at Sydney, commissioned in 1996, is currently Airservices’ most modern in way of technology. Four brand new control towers are currently being constructed at airports in Melbourne, Adelaide, Broome and Rockhampton and will be fitted with a new suite of operator consoles fitted with the latest systems, hardware, networking and communications technology.

The new tower technology will provide each tower controller station with up to four customisable touch screens capable of displaying electronic flight strips, operational information, weather, terminal area information and where available, surface surveillance radar data. This technology will be progressively rolled out to Airservices remaining 24 towers, including Sydney, as they are refurbished or rebuilt under its extensive tower replacement and refurbishment program.

While the future for aviation at Sydney is one of continuing growth and competition, it comes with increasing complexity and congestion, greater community expectations, challenges of airspace use and the need for stronger environmental controls. Overall, air traffic growth in Australia is expected to grow at a rate of 2.8 per cent, per annum, over the next 20 years. When compounded, year on year, this growth represents an increase by almost 60 per cent by 2030. Airservices recognises the need for significantly greater co-operation among aviation industry players and sees its role as connecting the Australian aviation industry to deliver world best industry performance if the complex challenges of future growth are to be managed and met.