CDM

For Australia, some airports and route pairs have considerable congestion during certain periods of the day. Air traffic congestion at Sydney Airport is well known. Of Australia’s 4.2 million annual air traffic movements, one-third occur within the Brisbane-Sydney-Melbourne triangle. The Melbourne-Sydney route is the fifth busiest in the world while the Sydney-Brisbane route rates seventh.

Perth Airport, meanwhile, regularly has up to 102 flights looking to depart within a three hour period on Tuesday, Wednesday and Thursday mornings due to high demand fly-in/fly-out (FIFO) charter demand. This includes 60 aircraft looking to depart in the first hour, yet the capacity of the airport and ATM infrastructure can only accommodate 40 departures per hour. Australian air traffic movements are forecast to grow at around five per cent per annum.

“During certain periods of the day the Melbourne-Brisbane-Sydney triangle is as congested as the busiest in Europe and North America.”

Jason Harfield, executive general manager ATC notes: “During certain periods of the day the Melbourne-Brisbane-Sydney airspace triangle is as congested as the busiest in Europe and North America. At these times user demand exceeds the ability of the ATM system to provide a service without increasing delays.”

Airservices’ National Operations Centre (NOC), located in Canberra, is a significant CDM mechanism that strategically addresses capacity issues as well as transcontinental route planning. Responsibilities of the NOC include providing strategic and pre-tactical flow management for major airports, facilitating and publishing transcontinental flex tracks, fitting training or non-standard operations into the traffic mix, being the communication coordination point for airport or airspace emergency services and finally, providing NOTAM and pilot briefing services. A forecaster from the Bureau of Meteorology (BOM) is a member of the team, to incorporate next-day weather forecasts into route planning and airport capacity determination. Forecasters also assess the impact of significant weather on real-time system capacity. The NOC has a team of approximately 12 people per shift.

Flex tracks deliver significant operational cost savings to airlines. Jennifer Birdsall, Airservices NOC Line Manager, describes the process of providing these tracks.
“Flex tracks enable airlines to gain substantial fuel savings by flying routes that take advantage of prevailing wind conditions. They are provided for east-west routes and for night time operations. A number of alternative flex track routes have been previously nominated by airlines. We prepare the flex tracks based on the forecast weather conditions for the following day, while complying with rules of the TAAATS ATM system. Flex tracks are published to airlines twice a day via NOTAM, presenting both a word and pictorial description of the route.”

Previously, flow management had been airport specific with major airports having dedicated flow control positions. These positions used the Maestro flow management software that is incorporated into the TAAATS system. However, this system only enabled the flow controllers to understand the traffic situation within their own area control centre not the control centres or at significant airports. Following its establishment in 2008 the NOC operated the Central Traffic Management System (CTMS) tool to provide strategic planning to assist flow control for Sydney and Perth airports. CTMS was replaced with an advanced flow management system called Metron Traffic Flow in March 2012. Metron is scheduled to be introduced at Brisbane Airport in December this year and Melbourne in 2013.

Information for Metron is added direct by airline users as well as NOC staff. Julianne Collingridge, Airservices NOC supervisor, explains: “Airlines load their next-day flight schedules into Metron each evening. Two systems are used to receive these flight schedules. Qantas, Virgin and Jetstar have a direct interface to Metron software from their operational IT platform to upload their schedules. Other airspace users provide schedule information via a web interface, again the evening prior.”

Concurrently, the Metron system is uploaded with weather forecasts for the next day, enabling predictions about the runways and flight profiles that will be flown. Software algorithms have been written to reflect the time associated with each phase of flight that will occur with each weather scenario. Performance characteristics of the various aircraft types are also incorporated. This provides the arrival and departure rate that will be available.

Metron then processes the proposed flight schedules with the predicted arrival and departure rate. A simulation of the proposed traffic situation is undertaken to assess the balance between traffic demand and ATM system capacity.

“The outcome of this process is that departing aircraft are assigned an operating time, while arriving aircraft are given a target arrival time. In the case of more than one aircraft seeking the same time, Metron randomly chooses the order and places other aircraft into slots as close as possible to their requested time.”

Collingridge highlights the process of assigning delays. “The aim of Metron is for traffic demand not to exceed ATM capacity. When demand exceeds this capacity a ground delay is most commonly issued to aircraft, except that we do not issue ground delays to international flights, since these flights can mostly adjust their arrival times during the en-route phase,” she added.
Following the determination of arrival times and departure slots, a conference call is held between the NOC and airline operational representatives. This conversation highlights significant weather and traffic issues that are expected the following day. Any changes to the assigned slot times are not undertaken directly by the NOC. Instead the NOC will facilitate a discussion between different organisations to see if agreement for a swap can be reached. Arrival and departure time assignments are finalised at 0130 UTC. Changes to departure slots, once finalised, need to be managed by the appropriate control tower.

During the course of the day the NOC monitors the active traffic demand, ATM capacity and weather conditions at towered airports. Information is displayed on individual consoles as well as large displays visible to all NOC operators. Colour coding of information is used to highlight when traffic or weather parameter conditions enter a critical zone such as low cloud or excessive crosswind causing a reduced arrival and departure rate. Traffic simulations are performed as needed throughout the day to assess the impact of unpredicted events. Revised arrival and departure rates are then reflected in a recalculation of the arrival times. When needed these changes are alerted and explained to airline users via conference calls throughout the day.

The NOC maintains a real-time view of aircraft enroute to both Sydney and Perth. For Sydney this extends for 2,600nm from the airport. Although the view for Perth only extends for 800nm it encompasses the majority of resources traffic that originate from remote areas of Western Australia. These views enable an assessment of the necessity to assign delayed arrival times to aircraft that are already on the enroute phase. Applying an enroute delay early assists aircraft adjust their flight profile to meet an amended arrival time. Amendments to the target arrival time are coordinated with the flow controllers responsible for Sydney and Perth, who manage the interaction with the aircraft.

The introduction of Metron has significantly reduced airborne delay. At Sydney these airborne delays have reduced from 20-30min on a ‘bad’ day with parallel operations, to under three minutes on average. Delays are now mostly absorbed enroute or on the ground.

Ground delays for FIFO services to/from Perth have caused some concern. Some FIFO airlines have adherence to schedule performance measures in their contracts with resources companies. There are instances of FIFO operators discounting the restrictions imposed by the flow management system to ensure that their contract obligations are met. There are other examples where airlines have chosen to get airborne from a remote airport, rather than remain on the ground and be affected by adverse weather. In circumstances when the departure slot or target arrival times are not adhered to, air traffic controllers have defined procedures that are applied. Aircraft are advised of their breach and when necessary airborne delays are effected i.e., radar vectoring or holding patterns.

Metron is also changing, in part, the role of air traffic control. Harfield explains: “In the past air traffic control has involved the tactical management of aircraft to resolve traffic flow congestion. With Metron, air traffic flow management moves into pre-tactical and makes greater use of movement planning to solve congestion ahead of the flight. This increases the traffic handling capacity of our air traffic controllers.”

The NOC and application of the Metron flow management system are starting points for a significant change to the way in which airlines, airports and Airservices conduct their operations with one another. Harfield explains: “Previously when the capability of the ATM system could reasonably comfortably meet aircraft demands, our focus was on improving the efficient use of airspace. This allowed airports, airlines and air traffic control to operate relatively independently with structural inefficiencies able to be absorbed. Now with greater demand, there needs to be a mind shift about how we work together. We now need to conceptualise the ATM system as a network that manages and interacts with other operational networks.”

Airlines have considerable experience in managing network operations. They understand the impact of a delay or disruption at hub airports or to some backbone services on their flight schedules and the movement of passengers on connecting services.

Airservices is gaining experience and understanding about adopting a network view and applying necessary systems and procedures. A joint CANSO/Boeing report in 2012 highlighted this evolution: “ANSPs need to change from directing to managing flights. They also need to perform the role of broker by bringing together airlines and airports to implement new efficiency initiatives as well as undertake strategic planning of operations.” As ANSPs, like Airservices, require and receive greater information from airlines, maintaining equity in service access and protecting commercial confidences, when dealing with a variety of competing organisations, is essential.

In some ways incorporating a variety of airports into this network view presents a significant challenge. Their natural business focus is directed at passengers arriving or leaving the airport and management of commercial property. When the ATM system had surplus capacity and generally applied airborne delays, it enabled airports to operate quite independently from both the ATM environment and other airports. The increased use of ground delays means that more aircraft will be on the ground for longer periods. This places greater stress on the planning of gate availability and apron space. Ground delays and the use of flow control systems that consider airport infrastructure in the determination of the arrival and departure rate inevitably draws major airports into the ATM system.

Harfield provides an example: “Major taxiway work at Melbourne as part of the development of Terminal 4 will mean that aircraft need to spend more time on the runway to avoid this area. Not only will these works reduce the arrival and departure rate at Melbourne, they will also have a flow-back impact on operations at Brisbane and Sydney. We now need to recognise that the traffic handling capacity of one airport has a direct impact on other airports. Also that undertaking substantial works at major airports needs to be coordinated with Airservices as well as other airports.”

One of the significant challenges to improving total network capacity is the costly investment in airport infrastructure. A Deloitte (2011) report presents a cost benefit analysis for implementing the SESAR and NextGen system initiatives globally. It found a positive net present value (NPV) for industry-wide investment assuming the full system deployment occurred in 2026. A greater NPV occurred if deployment occurred in 2020, while lessening if the programs were delayed until 2030. Sectors expected to accrue benefits are airlines 31 per cent, general economy 30 per cent, passengers 34 per cent, and ANSPs/airports five per cent. The report did not include the costs associated with improving airport infrastructure such as additional runways, rapid exit taxiways and gate parking. It is noteworthy that the very high capital cost in airport infrastructure may result in limited financial return for airport companies. Without investment in airport infrastructure, airspace capacity enhancement initiatives will flounder.

The volatility in the airline industry makes longterm planning for airports and Airservices quite difficult. The decision horizon for airlines is much shorter than ANSPs and airports. While fleet replacement decisions can take place over a number of years, new airlines can enter the market with a few months’ notice and others leave almost immediately. Schedules can change on a daily basis. Furthermore, the business and operating models of the various airlines is quite disparate. Airservices and airports need to provide services and infrastructure to cater for these differences.

Underlying the Deloitte report is concern about the ability of the global ATM industry to implement generational system change. Most of the proposed operational concepts for post 2020 were published by the FAA in 1981! As the European and North American programs have progressed, significant issues about system complexity and funding have emerged. As a result, the intended implementation timelines are slipping. There is great reliance being placed on the ICAO ASBU program to achieve global adoption in a pragmatic manner.

Two major projects currently being undertaken by Airservices – the control tower INTAS program and joint civil/military ATM systems – will enhance CDM capability. Both are built on the premise that control towers and the ATM systems platform are nodes from which to provide and receive information from a variety of aviation users in real time.

Other developments such as the advanced guidance lighting control and management system currently being implemented at Changi Airport in Singapore provides a technological and operational bridge between ATM and airport systems. This system uses surveillance and flight data information to guide and provide separation for aircraft between the runway and gate. They interface with A-SMGCS and surveillance systems typically provided by ANSPs as well as lighting and gate management systems provided by airport companies.

Eurocontrol, following a study of seven airports during 2007, concluded that positive benefits arise from the implementation of airport-based CDM. Benefits accrue in four broad areas. Ground handling agencies have the opportunity to deliver an improved and lower cost service by receiving accurate aircraft and passenger movement data. Airport companies are able to optimise their use of infrastructure, such as improved tactical gate allocation. Up-to-date information also enables resources to be directed to areas to improve passenger throughput. Relevant information provided to passengers also improves the image of the airport. Aircraft operators are able to improve punctuality. (Eurocontrol reported in 2003 that CDM improved on-time departure by 15%, while late departures reduced by five per cent). The immediate and knock-on effects of delay are visible enabling these costs to be more tightly managed. Lower operating costs also occur, such as a 10 per cent reduction in taxi time. ATC obtain benefits through a more regulated traffic flow that increases the number of aircraft able to be managed by air traffic controllers. This increase in effective network capacity is estimated at four per cent.

CDM initiatives are already being implemented in Australia that are changing the way airports, airlines and Airservices interact. These initiatives will increase with the implementation of the joint civil/military ATM system.