The Australian aviation industry is no stranger to change. We have adapted to new technologies throughout the years which has enabled us to continually improve the services we provide to Australian airspace users.
Until The mid ‘30s there was no formal air traffic control in Australia. Few aircraft carried two way radio equipment. Those that did could not communicate with Coastal Radio Stations or with the fledgling Aeradio organisation.
Director of Signals at RAAF Headquarters, Squadron Leader C.S. Wiggins joins Civil Aviation Branch to plan a system of Aeradio stations throughout Australia and New Guinea. Some 15 Aeradio stations were initially installed at principal aerodromes and along major air routes between Hobart and Salamaua.
Australia’s first Aerodrome Control Officers (ACO) are appointed at Archerfield, Mascot, Parafield and Essendon. Their function is to regulate air traffic at aerodromes, provide a meteorology service and advise pilots of cross-country flights.
The personal qualities required of ACOs were ‘mature age, discipline, power of command and level-headedness’.
Lacking radio communications, ACOs used visual signalling devices including the Aldis signalling lamp and Very cartridge pistol. At Essendon and Mascot they operated from rudimentary Control Towers on the rooves of the Aero Clubs.
From these towers hung red and cream cane balls, which were raised or lowered to indicate aerodrome conditions.
A signalling square located in front of the tower conveyed information on wind speed and direction and general aerodrome conditions.
Using a combination of red and green flare cartridges, and white or red signalling lights, they gave instructions to aircraft when to land, take off and taxi. These signals had an effective range of two miles.
Flight Checking Officers (FCOs) were introduced in 1940. Selected from experienced airline pilots they provided what would become known as a uniquely Australian aviation service, Operational Control.
Their duties were to check flight plans, ensure adequate fuel was carried, divert aircraft if destination conditions were unsafe, close airports if weather conditions deteriorated and to keep pilots informed of flying conditions.
After takeoff, the pilot was instructed by the Aerodrome Control Officer to ‘call Aeradio’ to transmit his position every half hour. Aeradio passed the position report on a slip of paper through a chute to the FCO who recorded the position and confirmed its accuracy.
The Royal Australian Air Force Wing responsible for providing air traffic control services to the Australian Defence Force is formed in 1942, known initially as No. 44 RDF Wing.
Under the control of North-Western Area Command, the wing was responsible for controlling the radar stations that acted as an early warning system for Japanese air raids. By 1943 the wing had a staff of 77 officers and other ranks.
As fighting had ceased in New Guinea and the threat of air raids on mainland Australia eased, No.44 Wing was disbanded in 1944.
Widespread installation of radio facilities during the war made it possible to take positive control of flights enroute. A ground organisation capable of exercising such control, including positive separation between aircraft, was established and the first Flight Control Manual was published.
The use of radio for Aerodrome Control made it possible to better manage aircraft operating near aerodromes.
Aircraft were separated by rudimentary rules: northbound aircraft flew at odd thousands of feet and southbound at even thousands. Aircraft flying at the same height along an air route had to be separated by 10 minutes flying time.
With aircraft of vastly different speeds on the same trunk air routes, a procedure was needed to maintain this longitudinal separation. In 1944 Sydney FCO Norman Rodoni invented the ‘Rodoniscope’.
It comprised a 60cm rotating circular glass disk, under which was a chart showing aircraft reporting points. At the outer edge of the chart was a clock face. By marking the position reports and circulating the glass disk in real time, the controller could see at what time Aeradio was likely to receive a position report and would then mark the actual position when the radio report was received.
This allowed accurate prediction of when faster aircraft would overtake slower aircraft.
A steady growth in air traffic, particularly on the main air routes between Brisbane, Sydney and Melbourne, led to congestion near these aerodromes.
The already overloaded radio communications facilities did not allow sufficiently rapid means of communication between Air Traffic Control and pilots.
A separate service called ‘Approach Control’ was introduced and evaluated on a trial basis at Essendon, Mascot and Archerfield in 1947. By 1950 the service was introduced where traffic density warranted such units.
At the same time Australian and New Guinea airspace was divided into ten large areas of responsibility, called Flight Information Regions.
The Flight Progress Board is introduced to perform two control functions:
At least four people were needed to work the board:
A need emerged for coordination between a control tower and the Air Traffic Control (ATC) Centre in the assignment of aircraft altitudes.
Without this coordination, there was the possibility different aircraft could be assigned the same altitude.
To obviate this difficulty, altitude assignment boards were developed in 1952, one of which was designed for building into the tower console, and the other for the Flight Progress Board in the ATC Centre.
To assign an altitude, the controller in the tower plugged into his board a flight progress strip. This assigned altitude was then indicated by a lamp in the control tower and a corresponding indication was presented on the Flight Progress Board.
If an attempt was made at the Flight Progress Board to assign the same altitude to another aircraft by plugging in a flight strip, alarms in both the tower and at the centre operated.
This method of separating air traffic within controlled airspace continued to be used until the mid-1960s when Area Approach Control Centres were established.
The International Phonetic Alphabet was adopted in March 1956. Up until then, civil aviation in Australia had used the British phonetic alphabet which had been extensively used during the war years. However, one of the early tasks of the new International Civil Aviation Organisation (ICAO) was to develop a more ‘international’ version of the phonetic alphabet, as elements of the existing phonetic alphabet were difficult to pronounce for people of non-English speaking background.
In November 1951 ICAO proposed a new phonetic alphabet, with feedback to reduce the number of times ‘ah’ and ‘o’ were used.
From 1 March 1956 a new internationally-agreed phonetic alphabet was adopted and is still in use today.
|Pre-1956||1951 Proposal||Post 1956|
The introduction of radar was a quantum leap for Air Traffic Control, moving from a static display to a completely dynamic radar display.
In 1961 the Department of Civil Aviation recommends the provision of dual-purpose radars for approach and area control at Brisbane, Sydney, Perth, Adelaide and Perth.
The upper limit of controlled airspace is increased to 40,000 feet to accommodate the introduction of domestic jet services.
The Secondary Surveillance Radar (SSR) requires target aircraft to be fitted with a receiver/transmitter which responds to a recognised signal radiated from a ground radar beacon.
Scan-converted Bright Radar Display Systems are incorporated in new Area Approach Control Centres (AACCs) established in Sydney (1965), Melbourne (1967), and Brisbane (1969).
Used across Australia from the mid-1960s, the Bright Display System presented raw radar returns overlaid by a video map showing airspace, routes and other important features. There was no labelling of returns, however SSR returns were displayed with a geometric symbol depending the code being squawked.
Target identification was done mostly by distance reports or observing a directed turn. Identification was maintained using ‘shrimp boats’ which were pieces of Perspex with target’s call sign written in chinagraph pencil, moistened and stuck on the screen by surface tension. The shrimp boats were manually moved along as the target moved.
The Air Traffic Control Autonomous Radar Display System [ATCARDS] later renamed the Australian Computerised Air Traffic System [AUSCATS], replaces many of the Bright Display Systems from the late 1980s.
AUSCATS was a radar data processing system able to perform simple functions such as SSR code/call sign correlation. The primary feature was a computer-generated, stroke drawn display which gave a very clear picture.
The computer-processed display enabled labels to be attached to tracks, as well as the new concept of ‘jurisdiction’, where a particular track was allocated to an individual controller. This enabled a ‘silent handoff’ of a track from one controller to another, improving efficiency by saving a considerable amount of voice coordination.
There was no flight data processing in the AUSCATS system, paper strips were used to record flight progress data.
The advent of satellite communications made possible the consolidation of outstation Flight Service Units into the capital cities.
Flight Service functions begin to be transferred to Air Traffic Control (ATC). The use of paper flight progress strips in civil enroute and Terminal Control Area (TMA) ATC ended at the turn of the 21st Century with the introduction of computerised air traffic management systems in the late 1990s. This included the Australian Advanced Air Traffic System, affectionately known as TAAATS.
As part of the TAAATS project, mirror-image Air Traffic Services Centres (ATSCs) were constructed at Melbourne and Brisbane airports, with Terminal Control Units located in Cairns, Sydney, Adelaide and Perth in refurbished existing accommodation.
The first units to transition to the new system in mid-1998 were Cairns TCU and the Reef Group sectors in Brisbane ATSC. The first southern unit to transition was the Melbourne ATSC’s Bass Group in December 1999.
In November 2000, No. 44 Wing was re-established in its current form and remains responsible for air traffic control services to the Australian Defence Force. It directly commands two squadrons, which in turn command 11 detachments throughout the country at RAAF, Royal Australian Navy, and Australian Army airfields as well as Darwin and Townsville international airports.
The Australian Advanced Air Traffic System [TAAATS] is one of two systems in use today and is used in both Flight Information Regions, Melbourne and Brisbane. It is also used in Terminal Control Units in Adelaide, Perth and Sydney.
The other system is the Australian Defence Air Traffic System [ADATS] used by the Royal Australian Air Force to provide air traffic control services in military controlled airspace.