Australian Sat/Comm Success no content

The complete automation of ATC by method of ADS is of course someway off, 2005 to be precise. However, the mechanism for automation must be in place well beforehand. The first step towards complete automation in Australia has occurred recently with the involvement of Sydney ATC and Qantas with initial trials being conducted last September and set to continue for some time. The recent trials conducted were centered on the use of Datalink and Flex Tracks.

These experiments are a precursor to complete autolysis. ADS offers increases in air traffic capacity and all round efficiency, minimising the difficulties associated with today’s antiquated system.

Satellite navigation and communication technology has already begun to revolutionise Australian ATC functions. Sydney oceanic control, the unit responsible for controlling that large expanse of airspace beyond Very High Frequency (VHF) radio range and land based radar, is the first Australian ATC unit to benefit from this modern technology.

ATC in this country is based primarily on radar and VHF communications,both of which are limited by the fact they are line of sight systems. Sydney oceanic control responsibility starts at 160nm (296km) from Sydney. However radar only extends out to 160nm (296km)from Sydney andVHF on a good day only extends out to 250nm (463km). So it can be seen that very little of Sydney oceanic control involves the use of either VHF or radar. Continuous position reports are thus required, (using today’s archaic technology) usually passed every 30 to 60 minutes by pilots using high frequency (HF) over the horizon radio. Until now this form of reporting has been the only means for tracking oceanic flights.

Separation standards as they exist today are also the result of possible equipment failure or human error. High level aircraft must be separated by 2000ft vertically and up to 15mins laterally. (Aircraft within 350nm (648km) radius of Sydney can have the lateral distance separation reduced to 10mins). Increasing air traffic over the next decade necessitates the move towards automation. The physical limitations of today’s archaic system has the potential to seriously undermine air travel both in this country and abroad.

The Civil Aviation Authority (CAA) is currently overhauling all Australian airspace, bringing us into line with the International Civil Aviation Organisation (ICAO) airspace standard. Our”new” airspace will be modelled on the United States and Canadian airspace examples! By 2005, ADS will eradicate the need for voice communications, which are inherently slow, throughout oceanic airspace and most of controlled airspace. It is unlikely terminal . airspace will be affected, due to the proximity ofVHF outlets and time factors involved with terminal operations. Replacing essential information by the use of datalink, where it in turn can be displayed by monitor where controllers can easily access it, is possibly the most radical move towards 21st Century communications!

The very concept of transferring aircraft derived position reports via a digital datalink from an aircraft to an ATC display monitor has manifested itself in the guise of ADS. Australia’s first application of ADS has been recently conducted within Sydney’s oceanic airspace, using satellites to complete the air-to-ground aircraft reports. Trials were conducted in September 1992, between the CAA and Qantas, where aircraft position reports were transmitted automatically at predetermined intervals, without any direct pilot input.

The Qantas crew preprogrammed the aircraft’s Flight Management System (FMS) prior to taxying. The aircraft’s FMS then reports the aircraft’s automatically. According to Bob Allen, Navigation Controller for Qantas,”At any stage the pilots can override any part of the datalink”.

In trials conducted to date, aircraft have passed all position reports and requests by datalink while ATC communications have been conducted using HF radio. Today’s technology position reports consists of the following:

•Aircraft callsign;

•Position and Time;

•Flight level and Mach Number;

•Next Position and Estimated Time.

Presently a free format system, the use of the datalink and satellite technology, is likely to change the basic position report to this: •Aircraft callsign and Time;

•Aircraft altitude;

•Aircraft latitude and longitude. *

The other forerunner of ADS affecting Sydney oceanic control is the generation and use of the “Flex track”. A flex track can best be described as the most cost effective direct track between two points. The tracks are generated by a computer daily after accessing forecast winds for particular areas and levels over the Pacific. This system was developed by the US Federal Aviation Authority (FAA) and issued daily by Oakland centre, located in San Francisco.

According to Alan Dukes,Oceanic Projects,CAA”The computer will only generate points which have a whole figure Lat’ and Long’ and where possible use existing waypoints to define the flex track”. Certain areas can also be avoided,for example the Williamtown restricted areas or Honiara’s uncontrolled FIR.

On a recently conducted trail, Qantas saved almost 15 minutes on a flight out of Los Angeles (LA) bound for Sydney. This figure is almost unheard of for LA/Sydney-bound flights. A 15 minute flight time saving, translates into 2000kg of fuel. Payload out of LA is often restricted,that 2000 kg of fuel saving could be used for carrying additional freight. 2000kg in fuel savings is worth about $700. However, the earning capability of an additional 2000kg of cargo is around $5000. Figures that naturally have Qantas excited!

• So far we have looked at the cost effectiveness of ADS. So what other benefits are available using these systems:

•Reduction in pilot workload;

•Reduction in frequency of communication;

• Reduction in frequency of congestion;

•Reduction in frequency delay;

•Reduction in misunderstandings;

•Reduction in separation standards.

With the introduction of ADS, air traffic management can begin to safely reduce separation standards,therefore achieving a corresponding increase in capacity and operational efficiency. “ADS can be considered a global reality. ” Already our adjoining airspace neighbours, Nadi and Auckland,”have their equipment installed and ready to go”, say’s Alan Dukes, when referring to their datalink capability.

Australia’s primary concern though is that of a need for a completely harmonised, compatible system in use throughout

the world.

* Lat’ and Long’ derived from either an Inertial Navigation System (INS) or Global Positioning System (GPS).