Tech towers

INTAS is part of the National Towers Program that will ultimately replace or refurbish all 28 control towers that Airservices operates across Australia. The first phase involved constructing four new control towers that were representative of all tower ‘types’ ie, Melbourne, Adelaide, Broome and Rockhampton, and equipping them with INTAS technology. Timing for the replacement or refurbishment of other locations is still to be finalised. Jason Harfield, EGM ATC explains: “In 2008 Airservices commenced a program to systematically refresh its asset base. As part of this program we identified a need to build new control towers. Sydney was our most recent control tower, constructed in 1998, but others were much older. For example Essendon was built as temporary structure for the 1956 Olympics and is still in use today. It is not possible to replace or upgrade all towers simultaneously, so we plan to smooth out the asset replacement program and get to a point where we are replacing a tower every two years, or so. The building program for stage 2 has not been finalised, however, we expect a new control tower for Sydney to be next due to the extensive airport development work that is being planned.”

Mr Harfield adds: “While en route and approach operations have received significant technology enhancement this has not been the case for control towers.”

A typical control tower has meteorology, communications, airfield lighting equipment, system monitoring and ATIS equipment housed in large fixed consoles situated toward the centre of the cab. Other specialist equipment such as radar displays, strip printers, display boards with paper flight progress strips, are placed on top, inside or near the console.

INTAS project manager Jason Hosmer outlines the problem: “An international control tower requires up to 30 systems to meet operational requirements. Controller positions in the old control towers can have three-four screens, each with a separate keyboard and mouse. Unbelievably a control tower position that we observed in the United Kingdom had seven screens and seven mice.”

Mr Harfield adds: “Space in control towers with centre consoles is tight. The existing tower systems are not really integrated into the Eurocat ATM system, therefore manual intervention is required to input data.” Air traffic controllers still have to write flight progress strips for local operations plus record transactions on the strip. They are also required to receive and send data using various systems. The tower clutter problem has been exacerbated by the introduction of advanced surface movement guidance and control systems (A-SMGCS) already at Melbourne and Sydney, with systems planned to be operational at Brisbane in the first quarter of 2013 and Perth during the second quarter of 2013.

In contrast, INTAS involves self contained controller workstations located around the perimeter of the control tower cab. Placement of controllers on these operational positions is flexible, depending on the traffic flow, whereby controllers can change workstations when needed, such as to gain a better view of aircraft using a crossing runway. INTAS involves having only four monitor screens in each workstation with control by touch screen or a single keyboard and mouse. Inputs from the various computer and control systems are consolidated in an equipment room beneath the cab and directed to the cab through workstation servers. All system components supporting INTAS now fit into three racks.

The core of INTAS is the tower data management system (TDM), built upon an existing product called EXCDS. EXCDS was developed by Nav Canada, the Canadian ANSP, which has commercialised a range of ATM products that were initially developed for its own use.

Mr Harfield briefly outlines the reasons for the choice: “This product was developed by air traffic controllers, therefore it has a high level of acceptance for our controller workforce. It is also scalable to meet the range of operational requirements that we have in Australia.”
Further development of the ‘off-the-self’ version of the TDM has taken place following the contract signing.

As Mr Hosmer explains: “Our INTAS contract required an integrated TDM solution to be developed by SaabSensis/Nav Canada. During the design phase Airservices adopted the Nav Canada development roadmap to introduce a java version of EXCDS to achieve and enhance the integration capabilities. The integrated solution developed for INTAS has been incorporated into Nav Canada’s internal release path and is now being sold commercially. It is also beginning to be rolled out through Nav Canada’s control tower organisation”.

Airservices control towers can be grouped into four segments based on the nature of operations and traffic levels, which are major international, capital city, regional and Capital City Class D towers (formerly named GAAP). INTAS systems at all locations will include TDM, operational data management systems (ODM), electronic surveillance system (ESS) for air situation displays and voice switch command control system (VCCS). Major airports also have A-SMGCS incorporated into ESS for ground surveillance as part of INTAS.
Sensis is the prime contractor and performs the role of overall integrator of the INTAS system. It has previously been contracted by Airservices to supply the A-SMGCS solution at major airports. The integration challenge, involving a large number of systems from different suppliers, is significant. It has also involved developing an interface between INTAS and the Thales Eurocat ATM system.
Eurocat provides the information for the air situation display, as well as being the single repository of flight data information for the TDM. The air situation display shows aircraft arriving, departing or operating in the vicinity of an airport. As with other radar displays, an aircraft symbol is assigned a label detailing the call sign, level and speed. Depending on the surveillance systems available at an airport, the air situation display will present aircraft information that is based upon radar (PSR and/or SSR), ADS-B and/or multi-lateration. When an aircraft position is not able to be determined by a surveillance technology, most commonly at regional airports, a flightplan track will be displayed.

The previous system required tower controllers to use flight information generated by both the Eurocat system along with manually prepared information about local traffic. Flight progress strips are prepared for all aircraft for controllers to record instructions and events. These strips are generated automatically when the aircraft’s flightplan is contained in the flight data system or, for local VFR flights, strips are hand written by the control tower staff. Therefore controllers were required to align locally generated information with that provided from Eurocat.

In contrast, INTAS requires that all aircraft are recorded electronically into the flight data system. Aircraft information is displayed electronically on the TDM in a similar format to that used on manual flight progress boards. Aircraft are recorded by strip colour depending on whether they are arriving (buff), departing (blue) or over-flights/specials (pink).

Up to three levels of information can be incorporated onto the electronic strips. Clearances issued to the aircraft are electronically recorded onto the strip using pop-up menus. Routine transactions, such as take-off time are recorded by touching the appropriate box on the electronic strip. Airports that have regulated operations involving standardised clearances ie, major international airports, are most easily addressed, often requiring only two levels to input required information onto the strips. Regional and GAAP airports that have a high number of local VFR operations require a greater number of levels to record necessary information on the strip.

Strips are automatically generated by the flight data management system, based on predetermined time parameters, when the controller needs to become informed of the aircraft. The TDM display groups aircraft depending upon their flight phase or route. At regional/GAAP airports, due to the high number of VFR aircraft and random operations, a revised INTAS screen configuration is used. In the place of an A-SMGCS display is an extended TDM, spanning two screens. This enables electronic strips to be displayed in a number of bays to represent operations on and around the airport.

In the old tower environment controllers were positioned side-by-side along the central console. When the responsibility for the control of an aircraft transferred from one position to another, a controller merely handed the paper strip to their colleague. In the new environment, controller workstations are not necessarily located in close proximity to each other and the transfer of responsibility occurs electronically from one TDM to another. Defining areas of responsibility for controllers around an airport in the ATM system, along with electronic transfer of responsibility, sees control tower operations becoming more similar to that undertaken by radar sectors.

Recording all aircraft information in the Eurocat flight data system also enables safety nets and alerts to be available for all aircraft.

Formerly this safety functionality could only be applied to aircraft whose details were recorded in the flight data management system, not for local VFR traffic that was manually recorded.

Work flow and business rules have been incorporated into the TDM logic which, as far as possible, will be applied by all control towers but with some adaptation to suit local operations.

Tower operations specialist Geoff Ross, explains: “Workflow and business rules determine the actions that can be performed by air traffic controllers for aircraft on particular routes and in specific weather conditions. For example we have established rules to allow the aerodrome controller to clear an aircraft for take-off, without prior approval of the departure radar controller, depending on the performance of the following aircraft, distance of aircraft on approach and weather conditions. This ‘auto release’ procedure reduces the coordination workload of the aerodrome and approach radar controllers.”

Underlying the development of workflow and establishment of business rules is defining the various modes of operation for an airport. An operational mode is selectable via a popup menu on the TDM which then activates a range of procedures that must be followed by the controllers. These procedures are written into the operational logic of the TDM. A controller’s actions are constrained by defining the information that can be entered onto the electronic flight progress strip, which reflects in the correct instructions issued to aircraft.

Selection of an operational mode also activates aerodrome systems. For example, nomination of CAT3 ILS mode automatically brings into operation different separation standards, procedures and various airfield lighting systems.

A Maestro flow management systems is currently incorporated into the Eurocat system. Airservices have recently acquired a Metron flow control system to better undertake capacity planning. These flow management systems interface into the Eurocat system, which sends data to the TDM to update/present information on electronic strips.

VCCS for each workstation is presented through the TDM. Two forms of display are available, either a short form window-presented on the display and activated by touch; or full functionality-accessed via the short form window. This VCCS system enables communications functions to be assigned to any workstation so that operational roles to be combined when reduced staffing is adopted in periods of low traffic.

The ODM provides a single front end display to consolidate an extensive array of equipment provided by many different suppliers. Information accessed through the ODM includes: aerodrome data and serviceability-such as online aerodrome charts and NOTAMs; AFTN messages; weather radar and data; airfield lighting; and emergency alarm monitoring. Controllers are able to update information transmitted via digital ATIS as well as perform controls on cabin equipment such as sunblinds, task lighting and door access.

An electronic image of the aerodrome and essential equipment is displayed on the ODM. This display highlights when a runway is not available for use by aircraft. It also presents areas of unserviceability on the airport as well as the operational status of airfield lighting. Of particular importance is the presentation of the operational status of stop bars (in operation at Melbourne and Sydney), whose operation regulates entry onto runways, preventing unauthorised incursions.

Airservices custom designed the workstations, with tThe same workstation design to be used in all locations and for all operational positions. Seven workstations, located around the perimeter of the cab will be installed at major towers. Other towers may have as few as three workstations.

Operational air traffic control staff have been used in the development of workstations, workflow and business rules. Jason Hosmer explains this design philosophy: “The workstations were developed internally from scratch taking account of the equipment to be installed and aerodrome operations. We visited a number of international sites and noted their best features. Air traffic controllers representing a variety of airports were then brought together in working groups. This process enabled us to decide upon the design functionality and ‘look and feel’ of both the workstations and the TDM, with a view that they could be applied nationally. We tried to replicate existing tower operations into INTAS, as much as possible. By replicating most existing operations we have been able to reduce controller training time on the new system.”

Due to the complexity of the project, INTAS development activities involved a large number of Airservices personnel with a range of skills sets. In addition to the 10 people in the core project team, a further 170 people have been involved in activities like operational working groups, engineering evaluations, technical system installations, safety case evaluations, human factor analysis, preparing new operational documentation or providing training.

INTAS provides a number of operational benefits. The use of electronic data and easy access to information will allow controllers to reduce the heads down time, enabling them to concentrate more on observing aircraft, which should lead to improved situation awareness. Further, spending less time on ‘low value’ tasks such as strip writing will likely increase their traffic handling capability.

Having aircraft data recorded electronically and stored within the flight data system, means that workload issues can be managed by both the tower and radar sectors. The electronic recording aerodrome data provides greater information about airport operations, which can be used to enhance airport efficiency.

One of the most interesting aspects of INTAS is as a forerunner of future ATM systems that will be introduced into Australia. The TDM, having all data recorded electronically and fully integrated into the Eurocat flight data processing system, provides a foundation for the exchange of aviation data across many organisations.

Jason Harfield describes how the management of data is now being conceptualised: “Control towers, along with other elements of the ATM system, now need to be considered as nodes that provide and receive system information. Future ATM systems involve a number of entities who provide and receive information, such as the various elements of the air traffic control system, airlines, aircraft operators and individual aircraft.” This information is both tactical, ie updated with the progress of the flight, or strategic, ie used for schedule planning, flow management and flight planning. Information exchange is a foundation for future ATM initiatives to meet traffic growth projections, while reducing user costs for services.

Responsibilities of air traffic controller positions in the control tower are likely to gradually evolve. Automation and associated business rules are likely to see more scope being given to the aerodrome (or runway) controller to be responsible for the initial separation of departing aircraft, without requiring the approval of the radar controller. Removing the need for manual and repetitive coordination enables the traffic handling capabilities of air traffic controllers to increase.

The clearance delivery and surface movement control positions are likely to become more strategic and more closely support the aircraft handling operations of the airport company. In the future, the greater use of pre-start ground delays is expected. To manage this process efficiently, real time information will be provided to airlines and airport companies detailing the available aircraft departure times. The tower ground positions will assist this planning management by ensuring aircraft start, taxi and arrive at the runway hold point in the correct order at the required time. New sophisticated guidance systems are becoming available that defines an aircraft’s taxi route between the runway and its allocated gate. These taxiing systems are integrated with docking guidance and airfield lighting systems (typically provided by airport companies) along with A-SMGCS and the flight data management system (provided by the air traffic service provider). This gate information is sourced from the airport company and emphasises the reliance on data exchange between the two entities.

In all INTAS represents a step-change in tower technology.