WAAS for Australia – you heard it here first!

[rjtjrt]

A WAAS like system would have been of assistance to the 737 crew in Mildura.
Never going to have ILS at more than a very very few regional airports that can justify it for other reasons, but WAAS will make approaches at night and poor weather safer even for airlines, as well as everyone else.

[Capn Bloggs]

but WAAS will make approaches at night and poor weather safer

If it gets rid of that mongrel Foxtrot waypoint, I'm all for it.

History being made here:

Dick, WAAS sounds like a good idea.

[27/09]

If it gets rid of that mongrel Foxtrot waypoint, I'm all for it.

I doubt it, at at least SBAS will mitigate the affects of the stupid GNSS approach design.

[27/09]

A WAAS like system would have been of assistance to the 737 crew in Mildura.
Never going to have ILS at more than a very very few regional airports that can justify it for other reasons, but WAAS will make approaches at night and poor weather safer even for airlines

Unfortunately Boeing and Airbus don't install avionics that can use WAAS (SBAS).

[alphacentauri]

I doubt it, at at least SBAS will mitigate the affects of the stupid GNSS approach design.

Why is that? Can't you fly them? They are pretty straight forward....

[Dick Smith]

Surely most US airline aircraft must already have WAAS GPS receivers? If not why did the FAA spend the money!

[27/09]

I doubt it, at at least SBAS will mitigate the affects of the stupid GNSS approach design.

Why is that? Can't you fly them? They are pretty straight forward....

Having a fix part way down the final of an NPA approach is plain dumb and potentially confusing. Most operators and schools I know of use and or teach the constant descent profile, which is easy to monitor with a single fix but potential confusing and dangerous with two fixes.

[27/09]

Surely most US airline aircraft must already have WAAS GPS receivers?

I stand to be corrected but as far as I know most Boeings and Airbus (even current build aircraft) have TSO 129 (non WASS) GNSS equipment, they don't need SBAS they have INS and/or DME/DME for augmentation.

If not why did the FAA spend the money!

My guess is to provide ILS type accuracy for the masses so that they could pull out all the ILS's they had at a significant number of airports. Remember the US had many more ILS's per capita than we have in this part of the world and ILS's cost a bomb to maintain.

[Check_Thrust]

27/09,

I do agree with you in regards to the possible confusion that can result from the use of multiple waypoints in a RNAV approach, however they exist to allow for multiple points to join the approach from and to provide a definitive FAF point which is also programmed into the GNSS as a cue to conduct its own RAIM check and to transfer to tighter tolerences in RAIM and CDI display.

An advantage of LNAV/VNAV and LPV approaches however is that vertical guidance is actually provided thus helping reduce the workload in maintaining a correct approach profile (though you will still monitor that the information being displayed is still correct).

Also judging from a quick look at RNAV charts from the FAA, there is no difference in regards to the waypoints due to the approaches being designed to allow for LNAV, LNAV/VNAV and LPV to be flown from the one chart and to account for the fact that the correct criteria may not be met for the more restricive minimas, for example: http://aeronav.faa.gov/d-tpp/1309/05050R21.PDF

[Capn Bloggs]

multiple waypoints in a RNAV approach, however they exist to allow for multiple points to join the approach from and to provide a diffinitive FAF point which is also programmed into the GNSS as a cue to conduct its own RAIM check and to transfer to tighter tolerences in RAIM and CDI display.

In one of the GPS boxes I have used, the boxes CDI scaled in before arriving at Foxtrot. I can't see why a system that can do so much needs physical waypoints to trigger actions. While perhaps being technically easy, Foxtrot is a menace and has ruined a fantastic concept.

[Check_Thrust]

I will not deny that the system could have been designed better but unfortunately without a major overhaul to exisiting system that would leave a lot of GNSS units incompatible with a new RNAV design we will no doubt be stuck with what we have for quite sometime to come.

Different TSOs and different manufacturers programming of their units result in them behaving one way or another. One example is a TSO-129 GNS430 will scale to CDI of 0.3 at the FAF, whereas a TSO-146 version of the same model will scale to 0.3 by the FAF and continue to reduce to a scale of 0.1 by the MAPT.

I will not defend the approach design we have for RNAVs, yes it could be better, maybe it was deemed to hard at the initial design phase of the TSO for the first GNSS that were to be RNAV capable to programme it differently and this has cascaded on to later designs, but at the end of the day a computer can be programmed to behave any way it is desired.

Another trap that have resulted from the waypoint designs is the failing of some people to compute in their minds that just because they are within 10/25nm of the IAF that they are tracking to does not necessarily mean they are within the 10/25nm MSA, however that is more so a situational awareness issue.

I suppose one benefit there has been from a FAF waypoint is to provide an easy direct to point for tracking to a 5 mile final when you are not conducting a RNAV approach, but yes, it wasn't designed for that and the potential for error that that waypoint provides whilst conducting an approach in trying conditions far outways the abovementioned benefit.

[27/09]

I will not deny that the system could have been designed better but unfortunately without a major overhaul to exisiting system that would leave a lot of GNSS units incompatible with a new RNAV design we will no doubt be stuck with what we have for quite sometime to come.

I believe the original GNSS approaches were designed for the US military and much of the legacy design does back to what was put in place at that time.

I believe if there was a will there would be a way major improvements could be achieved right now. I wonder if some of the problems arise from technocrats rather than pilots/users having the overriding input to approach design.

Why does the Foxtrot have to be at 5 miles or there-a-bouts, why not somewhere like where the profile intercepts the minimum straight in commencement altitude?

Another trap that have resulted from the waypoint designs is the failing of some people to compute in their minds that just because they are within 10/25nm of the IAF that they are tracking to does not necessarily mean they are within the 10/25nm MSA, however that is more so a situational awareness issue.

This is part of knowing how your nav aids work. TAA's and 25nm MSA'a are great things to use provided you use them correctly.

Enough of the thread drift. I think the introduction of SBAS to this part of the world is long over due. When you look at where SBAS is deployed around the world now it makes the south west Pacific area look very third world.

[Check_Thrust]

Why does the Foxtrot have to be at 5 miles or there-a-bouts, why not somewhere like where the profile intercepts the minimum straight in commencement altitude?

This has probably been inherited from the fact that most approaches (VOR, NDB, etc) have their FAF around 5nm to run to the threshold (though there are a few places that this is not the case, the Tumut, NSW (YTMU) RNAV comes to mind). Though I suppose you are really asking why does there have to be a waypoint for the FAF not just a fix based on a track and distance to run to the MAPT and have the GNSS unit conduct it's required functions at a much earlier point if it needs to rely on a waypoint for it to happen. I think the previously mentioned approach at Tumut is coming close but not fully to what you desire.

I do apologise for the thread drift.

On topic however I do agree that SBAS is long overdue to be brought to our part of the world. There are many regional as well as major aerodromes that can benefit from the advantages that this technology can bring (an LPV approach for runway 33 at Cairns comes to mind as there is only a localiser approach for it and guess which runway is typically in use during the wet!).

Anyway thats my 2 cents along with plenty of inflation.

[kimberleyEx]

Hi All.

As most who have posted on this subject, it would be a good thing that SBAS/WAAS be implemented in this part of the world.

The company I work for operate regional jets that are IRU (radio updating only) a/c.

We investigated various ways to integrate GNSS into the a/c to provide RNP LNAV approach and possibly Baro VNAV.

One option looked at:

http://www.esterline.com/Portals/17/...us/cma5025.pdf

Unfortunately we didn't proceed with this, as this system requires WAAS or GBAS to operate (on the GBAS option, if it became more widespread across the country, it maybe a attractive option for legacy a/c). But the whole idea of it was to provide a RNP approach capability at regional aerodromes.

No WAAS, and it wouldn't operate.

Now if WAAS were to be a reality here. It's a system that would be attractive and relatively easy to install.

Also it provides a distance to run to the DA (LNAV/VNAV or LPV) which would be handy for constant rate descents from 10nm (intermediate fix). Eg it emulates a ILS display in the flightdeck.

Canadian North installed this system on their 737-300. It works alright for them:
Avionics Magazine :: Canadian North 737 Certified for GPS/LPV

In the case of new build Airbus and Boeings, yes they can get by using RNP-AR. Installing a system such as this one or similar on offer from other avionics manufactures, would only benefit Regional turboprop and jet types in this country.

Regards.

K-Ex.

[Check_Thrust]

This article might be wrong as it refers to a "not yet published ICAO list" as its source, however it states that basically all biz jets and airliners (excluding the 787 and A380) have some form of WAAS/SBAS certification option available to them.

The fourth paragraph refers to the above mentioned:
Waas Delivers on Promises and Signals Further Innovation | Aviation International News

The article I think is fairly interesting and it also talks about GBAS and GLS approaches.

[Flying Binghi]

#36
...just farmers spending a few thousand dollars an hour of their own money on chemicals, wages fuel that needs to be placed accurately with large machines. It has got to the stage that wheels now do stop if RTK goes down or marine beacon signal drops out because without differential the potential losses from over or under spray is just to great. Just go and ask any larger farmer if he would go back to non diff auto steer and see what his answer is. Machines especially Spray machines don't even come with a mechanical marking option any more. New seeders are all linked to GPS variable rate application and reliant on it. So it isn't life threating its however becoming very reliant on it so I am told.

Its been over 30 years since i last operated broadacre rig so am not conversant with the latest tech. Though i can imagine just how useful GPS would be to operations.

Now, if GPS were lost to farmers tomorrow i'd imagine it would take all of a day or two to fit up the old fashioned markers. Not as efficient as GPS though all farmers would be on the same playing field so no marketable price differences there. There'd be no near blind farmer 'traffic control' to worry about either. If it were only farmers that were using GPS then it would not be a terrorist target of interest because of the minimal impact from the loss of GPS.

Unfortunately it seems there are some in the Oz aviation community who seem to want to make our airspace more and more reliant on a single navigation and traffic system.

The more reliant we become on GPS the bigger the target it becomes...








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[rjtjrt]

Day after election of Coalition.
Time to start gentle but persistent expert lobbying for this to become reality.
Perhaps can enlist the help of expert advice (eg the above mentioned Chris Rizzos - see post 31) re available options, and the not just aviation benefit.
The main caveat should be we must have a system that is fully and seamlessly compatible with the main world players, not a unique Australian system.
John

[7478ti]

WAAS (the Worthless Area Augmentation System)

Sadly, any move to implement WAAS in Australia would be an unnecessarily obsolete waste of money. With well over 30 SVs currently flying, the life of the Block IIs extended, Block IIIs on the way, over nearly 100 SVs planned and eventually likely to be used globally, with widespread global use of GBAS/GLS inevitable, Locata and other potential pseudolites used for multilateration on the horizon, and the fact that WAAS can never be used globally, it would be irresponsible to introduce WAAS/SBAS anywhere else in the world. In fact it is past time to start thinking about the decommission strategy for WAAS/EGNOS, just like the defunct IFR LORAN C, as an utter redundant waste of money. The future of Nav is in GPS, Galileo, and perhaps other basic SV constellations,via RNP, low cost inertial, GBAS, and likely even GBAS based multilateration. Since SA was turned off, and we have more than 30 SVs operational, and GBAS is now a reality (soon to likely even replace ILS), and multilateration via GBAS pseudolites is clearly possible (e.g., Locata etc), WAAS/SBAS is a system whose time has come, and passed, just like MLS (the Mythical Landing System).

[rjtjrt]

On the contrary Tom, waiting for these systems to be available to provide the sort of accuracy of SBAS now is folly.
I expect we can very quickly and inexpensively piggyback on the already functioning Japanese MSAS system. We presumably just need the ground element to be set up.
Practical now is much better than future pie in the sky.

[Denti]

This article might be wrong as it refers to a "not yet published ICAO list" as its source, however it states that basically all biz jets and airliners (excluding the 787 and A380) have some form of WAAS/SBAS certification option available to them.

The fourth paragraph refers to the above mentioned:
Waas Delivers on Promises and Signals Further Innovation | Aviation International News

The article I think is fairly interesting and it also talks about GBAS and GLS approaches.

Interesting article indeed. And quite contrary to what boeing told us. According to the OEM of our aircraft (both boeing and airbus) their equipment isn't LPV certified and therefore does not need to have WAAS and isn't equipped to that standard. However, at least on our boeings, GBAS is standard for the last seven years and RNP AR is possible without WAAS anyway as are BARO VNAV RNP approaches. As an airline (although based in europe) we do have zero interest in WAAS, EGNOS or whatever it is called. There was absolutely no advantage in having EGNOS operational for example, doesn't do anything for us. It is different in the GA community though, but quite understandable if airlines do not want to pay for a system that doesn't have a business case for them.