GBAS at YMML
Folks,
Did somebody mention that Gen.3 GPS, going up now, has almost WAAS (SBAS) accuracy without the augmentation ---- all accept for aircraft and high speed trains etc.
The for ever "coming soon now" Galileo, don't forget that the accurate signal is subscription only.
Tootle pip!!
Did somebody mention that Gen.3 GPS, going up now, has almost WAAS (SBAS) accuracy without the augmentation ---- all accept for aircraft and high speed trains etc.
The for ever "coming soon now" Galileo, don't forget that the accurate signal is subscription only.
Tootle pip!!
Last edited by LeadSled; 1st Apr 2015 at 08:49. Reason: typo
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SBAS True Costs
The real actual cost figures for SBAS are actually worse than $4B for the US alone. The numbers you're typically seeing from ANSPs and vendors (who usually have a stake in the outcome) are NOT the fully allocated costs. Further some locations are considering SBAS for "Political" reasons, and not technical reasons, or they are being talked into adopting it by vendors selling "stuff", or they are simply poorly informed as to the true options, better and less expensive alternatives, lack of real benefits, and hidden unnecessary costs. Galileo will eventually happen. But even before that, with 30+ GPSs and SA off, there is no longer any need for SBAS in the US or anywhere. That's why airlines have been safely and successfully flying both RNP .1, and some GLS too, totally without SBAS, for well over a decade now.
Now, if we had more rational criteria by authorities, and not the present over-specified and unnecessarily complex present criteria (e.g., exceedingly poorly framed AC20-138, 90-101, etc), ... then even $2500 total cost UAVs and other vehicles, from LSAs and low end GA up to retrofit jets, could even be using it routinely and economically too, with accuracy, integrity, and availability, ...all with simple low cost GNSS Kalman filtered sensors, in FMS equivalent nav and display systems.
SBAS is now an unnecessary system whose time has come, ...and gone.
Now, if we had more rational criteria by authorities, and not the present over-specified and unnecessarily complex present criteria (e.g., exceedingly poorly framed AC20-138, 90-101, etc), ... then even $2500 total cost UAVs and other vehicles, from LSAs and low end GA up to retrofit jets, could even be using it routinely and economically too, with accuracy, integrity, and availability, ...all with simple low cost GNSS Kalman filtered sensors, in FMS equivalent nav and display systems.
SBAS is now an unnecessary system whose time has come, ...and gone.
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Now, if we had more rational criteria by authorities, .....
As for the future with Galileo - the term "pie in the sky" comes to mind.
It is CASA and our Government with their head in the sand for proposing GBAS, and for missing out on SBAS, especially with much of the hardware for SBAS already paid for by Japan.
CASA appears to be trying to repeat the DME(A) going it alone with an orphan system with GBAS. GBAS has no future, except in Australia, where we waste money on stupidity, and a re parsimonious when it comes to common sense.
GBAS has no future, except in Australia
Here is some light reading on it.
http://ieeexplore.ieee.org/ieee_pilo...1/article.html
Tom Imrich:
That's why airlines have been safely and successfully flying both RNP .1, and some GLS too, totally without SBAS, for well over a decade now.
That's why airlines have been safely and successfully flying both RNP .1, and some GLS too, totally without SBAS, for well over a decade now.
In the last three months I have done GLS approaches in Germany, Switzerland, Australia and USA. So Oz is not alone with this.
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Augmentation state
Major air-transport FMSs and AFDS typically use whatever radio, GPS, inertial, and air data sensors are available, usually with either Kalman or second order complementary filtering. None have used SBAS since the advent of SBAS, as being completely unnecessary, and just contributing to excessive cost and complexity, as well as introducing new failure modes.
However for a few recent MMRs (poorly designed by avionics vendors so as to be able sell to multiple GA customers, with common components, and to politically cater to Europe's EGNOS) unnecessarily have incorporated some SBAS capability into their units. However that capability is still unnecessary and is largely unused, even if it is in the MMR or GPSSU. For the future, MMRs will increasingly incorporate "filtered" multi-constellation GNSS capability, often also including inertial filtering, for better accuracy, integrity, and availability (e.g., to minimize ANP/EPE growth). Note that inertial capability doesn't just mean expensive IRUs or ADIRUs. Inertial can be VERY LOW COST (e.g., even accelerometers or rate gyros), such as even now used in tiny low cost UAVs and model aircraft.
As for AFDS and autoflight..., modern air-transport systems typically can accommodate ILS inputs, or radio aid (e.g., VOR) inputs, and in particular FMS LNAV and VNAV (or equivalent) inputs. All modern air transport current production jets already have or have planned capability to accommodate GLS (which is GBAS).
The comment that GLS is only applicable to Australia is completely wrong.
GLS is already being used in many more countries than even cited in the earlier posts in this thread. GLS is a terrific system, that is now being incorporated in all modern transport jets because it is vastly better than ILS, as well as significantly less expensive in the long run than ILS, and is needed for some very important reasons technically, to work in conjunction with RNP (RNP will become the global NAV standard for the next century, or longer, for all airspace users, from tiny UAVs to GA, to air transport, to military, to space access and recovery, and GLS [GBAS] will play a key role).
Hence GLS (GBAS) with RNP are the global standard for the future. This is not just an Australia issue.
Instead, it is SBAS that is now an unnecessary obsolete complete waste of money (i.e., both WAAS and EGNOS), whose days are numbered, just like the once widely touted IFR Loran C and MLS. Just ask any air transport pilot flying into places like NZQN, or PAJN, or CYLW, or ZULS, if they'd now give up RNP. Or ask any pilot that's done a well over 25 kts direct gusting crosswind A/L on a 100' wide runway, with an engine shutdown in a wide body, while nailing the centerline within about 3ft laterally (yes it can now be routinely done, and it is truly amazing to watch).
However for a few recent MMRs (poorly designed by avionics vendors so as to be able sell to multiple GA customers, with common components, and to politically cater to Europe's EGNOS) unnecessarily have incorporated some SBAS capability into their units. However that capability is still unnecessary and is largely unused, even if it is in the MMR or GPSSU. For the future, MMRs will increasingly incorporate "filtered" multi-constellation GNSS capability, often also including inertial filtering, for better accuracy, integrity, and availability (e.g., to minimize ANP/EPE growth). Note that inertial capability doesn't just mean expensive IRUs or ADIRUs. Inertial can be VERY LOW COST (e.g., even accelerometers or rate gyros), such as even now used in tiny low cost UAVs and model aircraft.
As for AFDS and autoflight..., modern air-transport systems typically can accommodate ILS inputs, or radio aid (e.g., VOR) inputs, and in particular FMS LNAV and VNAV (or equivalent) inputs. All modern air transport current production jets already have or have planned capability to accommodate GLS (which is GBAS).
The comment that GLS is only applicable to Australia is completely wrong.
GLS is already being used in many more countries than even cited in the earlier posts in this thread. GLS is a terrific system, that is now being incorporated in all modern transport jets because it is vastly better than ILS, as well as significantly less expensive in the long run than ILS, and is needed for some very important reasons technically, to work in conjunction with RNP (RNP will become the global NAV standard for the next century, or longer, for all airspace users, from tiny UAVs to GA, to air transport, to military, to space access and recovery, and GLS [GBAS] will play a key role).
Hence GLS (GBAS) with RNP are the global standard for the future. This is not just an Australia issue.
Instead, it is SBAS that is now an unnecessary obsolete complete waste of money (i.e., both WAAS and EGNOS), whose days are numbered, just like the once widely touted IFR Loran C and MLS. Just ask any air transport pilot flying into places like NZQN, or PAJN, or CYLW, or ZULS, if they'd now give up RNP. Or ask any pilot that's done a well over 25 kts direct gusting crosswind A/L on a 100' wide runway, with an engine shutdown in a wide body, while nailing the centerline within about 3ft laterally (yes it can now be routinely done, and it is truly amazing to watch).
Or ask any pilot that's done a well over 25 kts direct gusting crosswind A/L on a 100' wide runway, with an engine shutdown in a wide body, while nailing the centerline within about 3ft laterally (yes it can now be routinely done, and it is truly amazing to watch).
Tom,
If I understand you correctly the augmentation systems you mention are basically the domain of the heavy passenger jet. What about your turbo prop and GA aircraft operating IFR into places other than where there is already an ILS or VOR? I don't think they can use stuff like DME/DME or other land based nav aids for augmentation even if they were available. These aircraft make up a significant proportion of the IFR fleet.
ICAO have a recommendation to have approaches with vertical guidance to each end of the IFR runways at all airports. Many Civil Aviation Authorities and ANSP's are adopting the ICAO recommendation. I know this includes the NZCAA and Airways NZ and likely CASA and Airservices.
While Baro VNAV fulfills the vertical guidance role for some aircraft it has some serious issues. For the majority of IFR, non jet transport aircraft, SBAS is the only game in town now and in the foreseeable future. No one I know of makes IFR certified avionics for these aircraft which has augmentation other than SBAS, nor are they likely to in the future. Like it or not all of this gear comes from the US and they have SBAS and don't need to cater for anything else.
SBAS gives approaches with vertical guidance to pretty well anywhere without the need for nearby ground based aids. To me it seems a perfect fit for Australia with its vast area and many remote airfields that would benefit from an IFR approach with vertical guidance. I'd imagine the likes of the RFDS guys and girls would appreciate such an approach on a dark night into some of the places they go.
If I understand you correctly the augmentation systems you mention are basically the domain of the heavy passenger jet. What about your turbo prop and GA aircraft operating IFR into places other than where there is already an ILS or VOR? I don't think they can use stuff like DME/DME or other land based nav aids for augmentation even if they were available. These aircraft make up a significant proportion of the IFR fleet.
ICAO have a recommendation to have approaches with vertical guidance to each end of the IFR runways at all airports. Many Civil Aviation Authorities and ANSP's are adopting the ICAO recommendation. I know this includes the NZCAA and Airways NZ and likely CASA and Airservices.
While Baro VNAV fulfills the vertical guidance role for some aircraft it has some serious issues. For the majority of IFR, non jet transport aircraft, SBAS is the only game in town now and in the foreseeable future. No one I know of makes IFR certified avionics for these aircraft which has augmentation other than SBAS, nor are they likely to in the future. Like it or not all of this gear comes from the US and they have SBAS and don't need to cater for anything else.
SBAS gives approaches with vertical guidance to pretty well anywhere without the need for nearby ground based aids. To me it seems a perfect fit for Australia with its vast area and many remote airfields that would benefit from an IFR approach with vertical guidance. I'd imagine the likes of the RFDS guys and girls would appreciate such an approach on a dark night into some of the places they go.
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You've appropriately described the issue
Your assessment well describes the current situation, but it is only because the GA avionics manufacturers were unnecessarily and inappropriately previously led down a false dead end criteria path, largely by AIR-130 and AFS-400 toward WAAS and LPV. Now GA is in a largely self induced financial and avionics capability "swamp" for both NextGen and Sesar that will be hard to drain.
SBAS is neither necessary nor appropriate any more. With SA "Off" and 30+ SVs, plus good Baro VNAV, and especially with Kalman filtered inertial, SBAS is now an obsolete waste of money. LPV horrendously unnecessarily wastes airspace (obsolete angular criteria). Whereas, RNP is still able to serve the NAV mission better globally, and less expensively. Hopefully the GA avionics manufacturers are starting to "see the light", and recognize the key role for RNP, Baro VNAV, and GLS/GBAS as they evolve their current avionics lines. Even the BizAv avionics lines are slowly gravitating to RNP. They are retaining the SBAS elements only because of their existing poor designs, that typically don't complementary filter their sensor data well, and their hesitancy to dump now increasingly obsolete product lines. But, they need to do that anyway, because their systems are typically poorly engineered from a human factors interface perspective from the start, because they need to move to multi-constellation GNSS sensing anyway, and because inertial component costs are dramatically falling in cost and can be readily integrated now (even tiny UAVs now use filtered inertial components with GNSS).
So yes, there may be some temporary merit in flying an "ILS like" approach with RNAV systems at some locations, ....but the EXACT SAME THING could be done better, cheaper, and quicker with using RNP (WITHOUT WAAS or EGNOS). Authorities readily have the ability to "Fleet Qualify" existing nav systems for RNP, essentially the same way the airline FMSs were "Fleet Qualified" for the equivalent of RNP back in the 1990s (e.g., KEGE - which has been operating completely safely now by several airlines for well over 20 years).
The exact same thing could be done for GA, except for the intransigent of authorities, and now vested interests of a few big avionics manufacturers.
Q.E.D.
O
ti
SBAS is neither necessary nor appropriate any more. With SA "Off" and 30+ SVs, plus good Baro VNAV, and especially with Kalman filtered inertial, SBAS is now an obsolete waste of money. LPV horrendously unnecessarily wastes airspace (obsolete angular criteria). Whereas, RNP is still able to serve the NAV mission better globally, and less expensively. Hopefully the GA avionics manufacturers are starting to "see the light", and recognize the key role for RNP, Baro VNAV, and GLS/GBAS as they evolve their current avionics lines. Even the BizAv avionics lines are slowly gravitating to RNP. They are retaining the SBAS elements only because of their existing poor designs, that typically don't complementary filter their sensor data well, and their hesitancy to dump now increasingly obsolete product lines. But, they need to do that anyway, because their systems are typically poorly engineered from a human factors interface perspective from the start, because they need to move to multi-constellation GNSS sensing anyway, and because inertial component costs are dramatically falling in cost and can be readily integrated now (even tiny UAVs now use filtered inertial components with GNSS).
So yes, there may be some temporary merit in flying an "ILS like" approach with RNAV systems at some locations, ....but the EXACT SAME THING could be done better, cheaper, and quicker with using RNP (WITHOUT WAAS or EGNOS). Authorities readily have the ability to "Fleet Qualify" existing nav systems for RNP, essentially the same way the airline FMSs were "Fleet Qualified" for the equivalent of RNP back in the 1990s (e.g., KEGE - which has been operating completely safely now by several airlines for well over 20 years).
The exact same thing could be done for GA, except for the intransigent of authorities, and now vested interests of a few big avionics manufacturers.
Q.E.D.
O
ti
but the EXACT SAME THING could be done better, cheaper, and quicker with using RNP (WITHOUT WAAS or EGNOS)
Also would I be correct in understanding that if you say SBAS isn't necessary then neither is GBAS?
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GBAS will always be necessary
GBAS (but not SBAS) will always be necessary, for sub-meter positioning, for some complicated technical reasons, to get the needed ANP, with integrity and continuity. And for some other technical reasons.
I'd suggest talking directly with Alex P or Pat R about any current issues being worked with particular equipment in Australia.
SBAS hasn't been needed since SA was set to "Off", and since we now have 30+ SVs active. The situation for not needing SBAS only gets better in the future, with yet more and better SVs on the way, with multi-constellation MMR or GPSSU ops on the way also, and with better tightly coupled/filtered inertial.
I'd suggest talking directly with Alex P or Pat R about any current issues being worked with particular equipment in Australia.
SBAS hasn't been needed since SA was set to "Off", and since we now have 30+ SVs active. The situation for not needing SBAS only gets better in the future, with yet more and better SVs on the way, with multi-constellation MMR or GPSSU ops on the way also, and with better tightly coupled/filtered inertial.
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Tom Imrich:
That's why airlines have been safely and successfully flying both RNP .1, and some GLS too, totally without SBAS, for well over a decade now.
What augmentation system are they using?
That's why airlines have been safely and successfully flying both RNP .1, and some GLS too, totally without SBAS, for well over a decade now.
What augmentation system are they using?
No augmentation is required.
In regards to SBAS, I really dont ever see AUS investing in the stationary sats needed, nor the infrastructure to set this up. The US had 3, and when one died, they repositioned and reduced coverage area, and there are no plans to send up another.
