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Australia Transitions to GNSS Flight Ops

By Woodrow Bellamy III  | May 25, 2016
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[Avionics Magazine 05-25-2016] Australia will begin a new era in its aviation operations starting May 26, as the country's air transportation system transitions to using satellite-based navigation as the primary means of navigation for commercial flight operations. The shift to the use of Global Navigation Satellite System (GNSS) with a reduced ground-based air navigation network is part of an ongoing effort by the Civil Aviation Safety Authority (CASA) of Australia that required all Instrument Flight Rule (IFR) aircraft operating in Australian airspace to be equipped with GNSS avionics by Feb. 4. 
GNSS enabled cockpit. Photo: Airservices Australia.
The shift to GNSS operations is part of the Navigation Rationalization Project (NRP) headed up by the country’s Air Navigation Service Provider (ANSP), Airservices Australia. NRP will lead the de-commissioning of 179 ground-based navigation aids, including Non-Directional Beacons (NBDS), Very High Frequency (VHF) Omni-directional Ranges (VORs) and Distance Measuring Equipment (DME). That's nearly 50 percent of the total 415 ground-based navigation aids that are in operation throughout Australian airspace. 

The remaining ground-based navigation aids will form the basis of Australia's new Backup Navigation Network (BNN). Airservices Australia is maintaining the BNN as a GNSS contingency mode of operation in the event that an aircraft is unable to access the satellite service. Area navigation waypoints will replace decommissioned navigation aids where necessary, according to CASA. 
Aircraft performing IFR operations are required to be equipped with GNSS avionics defined by CASA's Civil Aviation Order 20.18. The requirements are applicable to both domestic and foreign registered aircraft operating in Australia. Going forward, aircraft are required to be equipped with GNSS avionics that enable [Required Navigation Performance] RNP1 terminal operations, RNP2 for continental routes and RNP4 or RNP10 with oceanic routes, according to Airservices Australia. 
"Under Civil Aviation Order (CAO) 20.182, from Feb. 4, 2016 all aircraft operating under the IFR must be equipped with a [Technical Standard Order] TSO C129, C145, C146 or C196a GNSS3 system. Amongst other things, because the RNP 1 and RNP 2 navigation specifications have been developed on the basis of these TSOs, this GNSS mandate has the effect that all Australian-registered IFR aircraft will be RNP 1 and RNP 2 capable," CASA states in a guidance policy document released to the industry at the end of 2015 to provide more clarity on the mandate.
Foreign operators do have an option for a two-year exemption from CASA's GNSS avionics mandate, based on CASA's Acceptable Means of Compliance (AMC) policy that was introduced in late 2015 through collaboration with the International Business Aviation Council (IBAC). The exemption requires foreign operators to pay a fee, and submit an online form accompanied by supporting documents. The exemption also requires foreign operators to have achieved an existing area navigation RNAV1 or RNAV2 operational approval from the civil aviation authority of the country in which their aircraft is registered.
CASA has also sought to minimize the impact on operators with CA 20.91, providing recognition of existing aircraft equipage and pilot qualifications that meet its GNSS mandate requirements. 
"For an aircraft to meet the deeming provisions in CAO 20.91, the GNSS installation must use GNSS as the only input for the area navigation function, for example the navigation system is not a multi-sensor [Flight Management System] FMS type (stand-alone GNSS systems and integrated avionics systems using only GNSS for area navigation meet this requirement) and have the Aircraft Flight Manual state the navigation capability of the aircraft. This may be in the form of GNSS (or GPS) En Route, Terminal, and/or Non- Precision Approach or RNP 2, RNP 1 and RNP APCH," CASA states in a regulatory guidance document released in January. 

The Australian civil aviation authority has stated that Australia's desire to move to GNSS as a primary surveillance source is an effort to reduce flight operational reliance on ground-based navigation aids as well as reduce the use of legacy approaches. It also aims to shrink fuel burn and flight times. 

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