RAIM Check
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Sorry if someone has posted this, I couldn't be bothered reading all the other opinions, but the NAIPS GPS RAIM prediction page says:
So if the people generating the NOTAMS think you should use the in-flight equipment for a prediction in addition to the NOTAM, that's good enough for me.
It also specifically says the RPS is for flight planning purposes only.
The Airservices Australia Receiver Autonomous Integrity Monitoring (RAIM) Prediction Service (RPS) provides predictions of RAIM availability for flight planning purposes only.
Pilots-in-command are reminded that the predictions are based on information received from the GPS Operating Authority.
In flight, pilots-in-command should use the RAIM prediction facility of their GPS equipment for RAIM availability predictions.
Presence of RAIM should be continuously monitored whenever GPS is used for navigation.
Pilots-in-command are reminded that the predictions are based on information received from the GPS Operating Authority.
In flight, pilots-in-command should use the RAIM prediction facility of their GPS equipment for RAIM availability predictions.
Presence of RAIM should be continuously monitored whenever GPS is used for navigation.
It also specifically says the RPS is for flight planning purposes only.
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So if the people generating the NOTAMS think you should use the in-flight equipment for a prediction in addition to the NOTAM, that's good enough for me.
BTW, It is NOT a NOTAM, even in AUS, perhaps bundled, but certainly not NOTAM format. (semantics)
In flight, pilots-in-command should use the RAIM prediction facility of their GPS equipment for RAIM availability predictions.
They also said
Presence of RAIM should be continuously monitored whenever GPS is used for navigation.
In reality, the RAIM prediction from the almanac is a useless waste of memory on the unit. The RAIM prediction is checked PRIOR to submitting the flight plan and departure. That is not done by the aircraft, but by fltops. The RAIM check must be done with the State approved source, which is NOT the unit prediction.
Predictions are based o a 24 hour timeframe, IF and only IF, your flight plan crosses the timeframe, do you need to re-evaluate RAIM prediction enroute. Again, this CANNOT be done from the ac, it must be done back at fltops. (unless you decide to violate the FAA rules and use you tablet to access the internet source for the RAIM prediction for final) hmmm.
I have fielded calls, in reality, many, many calls while an ac is enroute on an RNP procedure, and RAIM drops, (HAL). The frequently happens when the ac enters mountainous terrain. It should be noted that some RNP coded procedures are 400nm long in China. (ie you really, really cannot disco the procedure) in S America, you almost always have HAL on procedure.
underfire:
No, you are missing the point. Please read my previous post. Mixing up RAIM prediction with real time monitoring.
No, you are missing the point. Please read my previous post. Mixing up RAIM prediction with real time monitoring.
Lots of good information here:
http://www.google.com.au/url?sa=t&rc...67720277,d.dGI
http://www.google.com.au/url?sa=t&rc...67720277,d.dGI
RPS AVAILABLE
The Airservices Australia RPS is available through the NAIPS access. This
service provides three types of prediction – TSO C129 FD; TSO C145/6
FD; and TSO C145/6 FDE. These predictions are valid for 72 hours and are
available for aerodromes that have published RNAV (GNSS) approaches.
This system (based in the Brisbane ATS Centre) uses inputs from both an
inbuilt GPS receiver and also the US Government GPS status messages
advising when GPS satellites are planned to be out of service. The RPS
software is re-run each time a NANU (GPS NOTAM) is received. This
means that these predictions can be more accurate than just using your
GPS receiver prediction, as the receiver will not know that satellite ‘X’ will
be out of service at some time in the future.
The CASA CAAP 179A provides guidance on how these various RPS
outputs should be used for IFR GNSS fl ight planning. Essentially, the only
time RPS is operationally required is for primary means and RNP fl ights,
but common sense dictates it should be used for other RNAV (GNSS)
approach operations.
The Airservices Australia RPS is available through the NAIPS access. This
service provides three types of prediction – TSO C129 FD; TSO C145/6
FD; and TSO C145/6 FDE. These predictions are valid for 72 hours and are
available for aerodromes that have published RNAV (GNSS) approaches.
This system (based in the Brisbane ATS Centre) uses inputs from both an
inbuilt GPS receiver and also the US Government GPS status messages
advising when GPS satellites are planned to be out of service. The RPS
software is re-run each time a NANU (GPS NOTAM) is received. This
means that these predictions can be more accurate than just using your
GPS receiver prediction, as the receiver will not know that satellite ‘X’ will
be out of service at some time in the future.
The CASA CAAP 179A provides guidance on how these various RPS
outputs should be used for IFR GNSS fl ight planning. Essentially, the only
time RPS is operationally required is for primary means and RNP fl ights,
but common sense dictates it should be used for other RNAV (GNSS)
approach operations.
THE BOTTOM LINE
In summary, RAIM and its associated prediction services are a fundamental
part of adapting the GPS system for use in IFR civil operations. An
understanding of its role is essential to the safe use of GNSS.
The bottom line is that regardless of the RPS notification, if you have not
received a ‘RAIM not available’ or ‘RAIM Warning’, or equivalent message
(such as ‘Loss of Integrity”) from your GPS during IFR operations you
can continue GNSS operations. Conversely, if you do get such messages,
you must discontinue any approach operation using GNSS or, if enroute
in controlled airspace, advise ATC after five minutes.
In summary, RAIM and its associated prediction services are a fundamental
part of adapting the GPS system for use in IFR civil operations. An
understanding of its role is essential to the safe use of GNSS.
The bottom line is that regardless of the RPS notification, if you have not
received a ‘RAIM not available’ or ‘RAIM Warning’, or equivalent message
(such as ‘Loss of Integrity”) from your GPS during IFR operations you
can continue GNSS operations. Conversely, if you do get such messages,
you must discontinue any approach operation using GNSS or, if enroute
in controlled airspace, advise ATC after five minutes.
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That is probably the best explanation of the AUS service, what it actually does, and who really needs it....
Other Countries use some different parameters, so it is always good to check.
Here is the FAA Site RAIM Prediction-FAA which includes the route check
RNP APCH or RNAV (GPS) is well with reach of GA IFR
Other Countries use some different parameters, so it is always good to check.
Here is the FAA Site RAIM Prediction-FAA which includes the route check
I wonder how many "General Aviation" aircraft do RNP approaches?
Last edited by underfire; 29th May 2014 at 17:53.
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Dr.
For ICAO (and AUS) RNP APCH and RNAV (GPS) are the same.
For ICAO (and AUS) RNP APCH and RNAV (GPS) are the same.
RNP APCH is the general ICAO designator for PBN approach procedures that are not Authorization Required operations.
As GNSS fulfils the basic requirement of RNP for on-board performance and monitoring, both RNAV (GNSS) and SBAS LPV procedures are types of RNP APCH operations.
RNP APCH procedures will be identified as:
• RNP APCH – LNAV
• RNP APCH – LNAV/VNAV (where a vertical guidance system is used)
• RNP APCH – LPV (Localiser Performance with Vertical Guidance)
• RNP APCH – LP (SBAS approach where vertical guidance is not available)
As GNSS fulfils the basic requirement of RNP for on-board performance and monitoring, both RNAV (GNSS) and SBAS LPV procedures are types of RNP APCH operations.
RNP APCH procedures will be identified as:
• RNP APCH – LNAV
• RNP APCH – LNAV/VNAV (where a vertical guidance system is used)
• RNP APCH – LPV (Localiser Performance with Vertical Guidance)
• RNP APCH – LP (SBAS approach where vertical guidance is not available)
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More info on Performance Based Nav (RNP etc) in the Australian context may be found here.
The way I read it, it will be business as usual for GPS-equipped IFR aircraft. However, we will have to absorb a new terminology from the Dept for Name Changes. As noted by underfire...
The way I read it, it will be business as usual for GPS-equipped IFR aircraft. However, we will have to absorb a new terminology from the Dept for Name Changes. As noted by underfire...
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Oktas,
Agree, as noted, the terminology, or rather, the assimilation of the terminology to a lowest common denominator is rather irritating.
Having designed many of the tailored RNP-AR procedures in AUS, I am really not sure why ....
Stuff like RNP APCH LNAV just kills me for some reason....
Agree, as noted, the terminology, or rather, the assimilation of the terminology to a lowest common denominator is rather irritating.
Having designed many of the tailored RNP-AR procedures in AUS, I am really not sure why ....
Stuff like RNP APCH LNAV just kills me for some reason....
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Stuff like RNP APCH LNAV just kills me for some reason
But, they invented it, they developed it, they paid for (much of) it. So I can't complain about it. Except here, of course...
A question for you underfire.
Earlier you said that RAIM predictions are done no more than 24 hours in advance, and, for flights crossing the 24-hr mark, a new one is generated by Flt Ops. However, NANU are generated with 72 hour validity, and the almanac is valid for quite a long time, up to a week. Why is there a 24 hour limit on your predictions?
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OKtas,
NANU from Navstar is typically for 72 hours...these cover anticipated outages of Sats. These give you an idea of sat health and availability. You need other tools for flight planning.
As an example, the FAA RAIM prediction is based on a 24 hour daily cycle. It is also updated with 15 mins of an unexpected outage.
These sites are what you need for the route and approach RAIM availability. The route tools not only use the number of sats and strength, but will include the mask angle along the route and the individual approach.
The mask angle is very important. In mountainous terrain, its pretty easy to start losing them and/or the signal to become sporadic, which throws off the error trapping of the GPS unit.
NANU from Navstar is typically for 72 hours...these cover anticipated outages of Sats. These give you an idea of sat health and availability. You need other tools for flight planning.
As an example, the FAA RAIM prediction is based on a 24 hour daily cycle. It is also updated with 15 mins of an unexpected outage.
These sites are what you need for the route and approach RAIM availability. The route tools not only use the number of sats and strength, but will include the mask angle along the route and the individual approach.
The mask angle is very important. In mountainous terrain, its pretty easy to start losing them and/or the signal to become sporadic, which throws off the error trapping of the GPS unit.
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Thanks underfire. Mask angle can be predicted a long time in advance, I think.
But I didn't know that FAA tools include unpredictable outages on an hour to hour basis. Thanks.
But I didn't know that FAA tools include unpredictable outages on an hour to hour basis. Thanks.
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Mask angle is difficult in terrain.
While the sats are in orbit, angles from each sat are always changing. While 5 degrees is the standard...terrain is the wildcard, especially when flying..
The RAIM prediction is just not set up for that level of detail. Its a guess, but as we open up areas of the World to Aviation, the holes begin to open up...
As you may be aware, I take nothing for granted.
Fly this, and lose RAIM and go to HAL..options? (notice the elevation)
While the sats are in orbit, angles from each sat are always changing. While 5 degrees is the standard...terrain is the wildcard, especially when flying..
The RAIM prediction is just not set up for that level of detail. Its a guess, but as we open up areas of the World to Aviation, the holes begin to open up...
As you may be aware, I take nothing for granted.
Fly this, and lose RAIM and go to HAL..options? (notice the elevation)
