Frequently Asked Questions


What is PBN? (Performance Based Navigation)


According to CASA's safety policy on Performanced Based Navigation;

"Global navigation requires global standards"

Equipment mandates:CAO 20.91 and 20.18 show us the required equippage for all Australian Registered Aircraft and its benefits.


Performance-based Navigation, or PBN, is area navigation that uses on-board systems and will be based on global navigation satellite systems (GNSS) in Australia. This is in contrast with traditional sensor-specific navigation based largely on fixed ground-based beacons guiding aircraft along published routes via waypoints defined by these beacons. PBN defines aircraft navigation requirements in terms of the accuracy, integrity, continuity and functionality required for the proposed operations.


Navigation using legacy ground aids is ‘relative navigation’ since aircraft are always operating relative to the navaids — whether tracking to or from aids, or flying to a point defined by a VOR radial and DME distance from a ground station. PBN, on the other hand, is ‘absolute navigation’ — the aircraft operates by first determining its present position in terms of latitude and longitude, and then where this position is in relation to the intended flight path.

This has the major advantage of flexibility: providing the aircraft has a means of determining its current position, it can operate anywhere that positioning system will operate.

Read More...For the full Booklet on WHAT IS PBN? (1.9Mb)



What is ADS-B?


ADS-B is a replacement for (or supplement to) traditional radar based surveillance of aircraft. ADS-B is a major change in surveillance philosophy – instead of using ground based radar to interrogate aircraft and determine their positions, each aircraft will use GPS to find its own position and then automatically report it.


Why would we want ADS-B?


There are three benefits driving the transition to ADS-B. Firstly, the GPS positions that are reported by ADS-B are more accurate than the current radar positions and are more consistent. This means that in the IFR environment closer spacing can be used than at present, and this provides much-needed capacity improvements in congested airspace. Secondly, ADS-B surveillance is easier and less expensive to deploy than ground radar. This means that airspace which previously had no radar and only procedural separation services can now have the benefits of ATC services. And finally, because ADS-B is a broadcast service that can be received by other aircraft as well as ATC on the ground, ADS-B offers the option for an aircraft to have accurate and inexpensive traffic awareness of other nearby aircraft.


The ADS-B mandate for all IFR aircraft to be ADS-B capable comes into effect Feb 2,2017.

Read More... Helpful questions on ADS-B from Garmin​ (Some information is US-only, e.g: UAT 978 not in AUS)



GPS - What is WAAS?


WAAS = Wide Area Augmentation System

Basically, it's a system of satellites and ground stations that provide GPS signal corrections, giving you even better position accuracy.


How much better? Try an average of up to five times better. A WAAS-capable receiver can give you a position accuracy of better than 3 m, 95 percent of the time. And you don't have to purchase additional receiving equipment or pay service fees to use WAAS.


How it Works

WAAS consists of multiple ground reference stations positioned across the U.S. that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through 1 of 2 geostationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal.


Who benefits from WAAS?

Currently, WAAS satellite coverage is only available in North America. There are no ground reference stations in South America, so even though GPS users there can receive WAAS, the signal has not been corrected and thus would not improve the accuracy of their unit. For some users in the U.S., the position of the satellites over the equator makes it difficult to receive the signals when trees or mountains obstruct the view of the horizon. WAAS signal reception is ideal for open land and marine applications. WAAS provides extended coverage both inland and offshore compared to the land-based DGPS (differential GPS) system. Another benefit of WAAS is that it does not require additional receiving equipment, while DGPS does.


Other governments are developing similar satellite-based differential systems. In Asia, it's the Japanese Multi-Functional Satellite Augmentation System (MSAS), while Europe has the Euro Geostationary Navigation Overlay Service (EGNOS). Eventually, GPS users around the world will have access to precise position data using these and other compatible systems.


It just keeps getting better

100 m: Accuracy of the original GPS system, which was subject to accuracy degradation under the government-imposed Selective Availability (SA) program. 

15 m: Typical GPS position accuracy without SA.

3-5 m: Typical differential GPS (DGPS) position accuracy.

< 3 m: Typical WAAS position accuracy.



GARMIN - Can I upgrade my GNS430 / 530 to WAAS capability still?

Yes you can, Garmin Australasia (through us in Sydney) has good turn-around times for upgrades at present (time of publishing this FAQ). Go to our CONTACTS page and enquire about prices & charges for upgrades and/or GNS 400W / 500W series products. Some of the legacy units have now become discontinued, please contact : for details on those units.


Can I purchase products online from Pacific Avionics ?

Yes you can buy some off the shelf items from our secure online shop.

You can certainly enquire about Purchasing any GPS/NAV/COM, AUDIO, TRAFFIC, TRANSPONDER equipment through our CONTACTS page. Our Sales team will answer all your related questions regarding equipment & installation costs.

We are now able to sell some limited products online, however you will need to talk to us regarding products that require Dealer or Service Centre installation to provide product support and quality fitment.


It is part of the Manufacturers Installation Policies that the Authorised Dealer must install any panel mounted equipment that they sell.

Please go our CONTACTS page and submit a request for any of our sale or new items that you find on our PRODUCTS pages.


GARMIN - Do we sell Garmin Handheld products over the counter?

Yes we do. First go to our PRODUCTS - Online Shop for listed GPS information and you can order and purchase from us there or come in to our Bankstown facility.




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