"...Public safety is a powerful argument..."

The aircraft has safely landed. SOP,s worked as advertised. Whats the drama about ?






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Hardly SOP's.
See

Investigation: AO-2013-100 - Weather related operational event involving B737s VH-YIR and VH-VYK at Mildura Airport, Victoria on 18 June 2013

As I said, public safety is a powerful arguement for Australia adopting a SBAS, equivalent to WAAS. It would make a much deeper layer of safety for multiple ops around Australia. It would have assisted significantly in this incident, where minima had to be compromised.

Wait until dual frequence GNSS is widespread
 

The big limitation about SBAS today (WAAS, MSAS, EGNOS) is the iono grid.
You need lots of reference stations to calculate a precise enough iono grid.
That's why there are no LPV approaches in Hawaii, even if the FAA were to add one station in every major island plus one in Guam, the Marshall Islands, still the iono grid calculation wouldn't be good enough.
But all of this ends with dual frequency GNSS.
Dual frequency receivers calculate iono corrections locally, more precisely than a centralized grid broadcast. For aviation that means L1 and L5 bands (the dual frequency pair).
Once that is true, it would take just 4 MSAS stations in Australia (perhaps one in New Zealand) to have full LPV coverage for the whole region.
All you need is one station in the extreme SW, NW, SE and NE corners of the region and you're done. While to do single frequency MSAS you would need a dozen stations for full coverage. The sole reason you need more stations is so satellites coming in view over antartica (that aren't in view of stations in Japanese soil) can be tracked properly, and have their ephemeris and clocks corrected. For that you need to do the reverse of what the GPS receiver does (get the signal on 4 stations with good geometry and compare where the satellite says it is vs where it actually is).
Finally, having MSAS support for Galileo will be a big part of this, cause they come with the L5 signal standard, while GPS is very slowly launching new satellites with L5 support. It's likely dual frequency SBAS will become doable mostly due to Galileo, as full dual frequency GPS coverage (at least 24 satellites) is expected to take at least until mid 2020s (if you use actual launch rates instead of the US Air Force way too optimistic schedules).
But with half GPS L5 coverage plus full Galileo coverage it would be arguably possible to even go CAT II approaches with SBAS.
Using full Galileo + incomplete GPS L5 support, enough coverage could be in place by late 2017 (assuming about 24 months delays over the current Galileo schedule).

Looked at L2 a few years back. Yes, birds are now ordered and start flying 2016. All operational with 24 birds by 2026. Looks good for precisely your comment on ionispheric distortions, macpacheco.

Wish those other characters would post here instead of the Smith thread:ugh:

edit-http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/mobileAll/WAASoftheFuture.pdf

Macpacheco

Thanks for the information. Very interesting and detailed points.

It seems there is a viable and reasonably economical path to implement this for us, and I think many would use and benefit from it, not just the aviation community.

John

Nice FAA document. Thanks OZBUSDRIVER. Wish the CASA stuff was as clear.

It makes you think that the current PBN plans based on WAAS will be a stopgap and that it might be eclipsed by L2 in the early 2020's.

I was told a few months back that there was consideration for rnp lnav/vnav approaches into essendon, Moorabbin, Avalon etc.

Trying to find some more detail about it but can't seem to find anything current.

Closest thing I could see is this doc. http://www.casa.gov.au/wcmswr/_asset...a/pbn-plan.pdf which covers plans for sbas until Multi feed gps units and satellites become available and no need for sbas.

What do we need to get sbas operational?

Would it allow for LPV approaches into these aerodromes?

What sort of equipment would you need in the aircraft?

In order:

Money, yes, and a TSO C146 series GPS receiver.

So doing some firther reading Australia might implement sbas as an interim to dual channel gps which isn't scheduled until 2020.

In other words we will need to wait until 2020.

Are there any gps precision approaches in Australia yet? Looking at the latest DAPs there are rnp approaches into some of the major airports but not sure how it's done? GBAS or SBAS? I know we don't have WaaS as it requires 25 ground stations to work in Australia.

They are labeled as rnp approaches which as I understand is just the new name for the RNAV (GNSS) approaches.

Can't seem to see on the plate if it has a vertical guidance or not.

WAAS is SBAS. SBAS is the overarching name for the various regional systems.

WAAS is the US SBAS system, there's others as well like EGNOS in Europe, GAGAN in India, MSAS in Japan, SDCM in Russia. China are bringing one on line too I think.

Interestingly Australia and New Zealand are about the only two places in the world outside of Africa and South America that don't have an SBAS system or at least an SBAS system in development. I hear there is a push at the moment to get a system in this part of the world. Not before time if you ask me.

RNP doesn't require any augmentation systems like GBAS or SBAS.

As I understand it under PBN, RNP ops require on board integrity monitoring systems i.e. RAIM and allow ops outside of controlled (radar) airspace whereas RNAV ops don't require on board integrity monitoring and are therefore conducted inside controlled airspace, the integrity being provided by the radar controller.

Both RNP and RNAV ops can use a variety of nav sensors to calculate the nav solution. i.e. INS, VOR/DME, DME/DME, GNSS.

The plate will either say LNAV for just lateral guidance, or VNAV for vertical guidance. Baro VNAV is another option using a baromertic input to the nav computer to give vertical guidance, this is pretty well only available on the like of an FMS system and not available for pure GNSS ops.

The plate labeling (i.e. LNAV or VNAV)will be beside the minima info for that approach.

If you're looking at a GNSS approach without the availablity of SBAS it's very unlikely there'll be any reference to VNAV, there might be a Baro VNAV option.

Then you have RNP AR approaches which do have curved segments and vertical guidance, but they're only available to operators who have approval (hence the AR tag). Right gear on board the aircraft with appropriate crew training.

Although not a specific Aussie reference the NZ CAA has published a draft version of what and how to comply with PBN. It is quite detailed but easy to navigate.

It details the specific differences for a Part 91 operation v a part 119 operation i.e. Private ops v commercial ops.


http://www.caa.govt.nz/Advisory_Circ...1-21_draft.pdf

So what was the media release at Sydney airport about them implementing GBAS. I thought this was so vertical guidance could be given without the need for an ILS. My thoughts were that Sydney had this capability as a precision approach?

The media release from a year or so ago said the new GBaS system was capable of handling a 100 simultaneous approaches in a 40nm area. Does anyone know if this actually exists?

The Kiwis have had LNAV/VNAV approaches for some time eg:

AIP New Zealand

To me this looks like Australia has now implemented its own version of SBAS but using a ground based system?


https://www.youtube.com/watch?v=xLvZu3TTz70


Is this just as an interim or are we expecting to see more of these around the country? By the looks of it you will also need to have some very specific equipment in your aircraft.


Does anyone have any official word on the development of SBAS within AU? It looks like it will cost approx. 60M?


Anyone from airservices here who can help explain why we have implemented such a specialised bit of hardware in YSSY and not used something that will allow for national coverage?

Sydney does have GBAS, on an approval-required basis.

If you want to fly to precision approach minima on a GPS derived position fix, the GPS data has to be augmented ("corrected for errors").

You can do this from space (SBAS / WAAS, wide area, expensive to run but cheap to use).

You can do it over a region (can't remember acronym), say 100nm x 100nm, but AFAIK no-one does.

You can do it for a terminal area (GBAS) with a base station and VHF data link to participating aircraft (small area, cheap to run and moderate expense to use).

In all cases the principle is the same. Laptop bolted to the ground assesses GPS position, compares it to true position. Uplinks error correction to satellite or participating aircraft. If satellite, correction is re-broadcast to participating aircraft.

There are other benefits too, such as real-time re-broadcasting of satellite health and integrity to a better standard than RAIM.

Thanks oktas8 and 27/09. Makes much more sense now.

I think I get it.. For the GA guys and gals we are going to have to wait for multi frequency or dual channel gps which allows for multiple gps constellations to provide data to a single gps unit. This would mean a hardware change but essentially you would be receiving two gps feeds. Therefore the unit could do its own error correction.

From all my reading it doesn't seem to be something that will be deployed in the near future. 2020 onwards I think.

:confused::confused::confused:

What happened to me previous post at #97.. ?











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Nose_WheelNo I don't think you're going to have to wait for new GPS units. It is my understanding that it's likely (though not guaranteed at this point) that SBAS will come to the South Western Pacific area i.e. Australia and New Zealand and surrounds within a year or three.

There's been plenty of obfuscation around SBAS. The installation costs have been wildly exaggerated.

There also seems to have been a reluctance from some quarters to advance the introduction of SBAS, why I'm not sure when it makes a lot of sense to have it. I suspect in some cases there might be ulterior motives. For one, the ANSP (Air Services or Airways) cannot charge for the use of the service unlike they could for a GBAS service.

Dredging up a old post for context.
Guidelines for SouthPAN based APV
New satellite dish commissioned at Uralla
2027! Looks like its actually going to happen.