RNP SID with RF leg
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FlightPath:
Because they ended up placing too many RNP AR approaches were they are not needed nor particularly useful. Their purpose is where a significant terrain issue can only be resolved with RNP AR and, in a very few cases deconfliction and noise abatement.
If the FAA would get off the dime about letting non-astronauts fly RF legs, than ordinary RNAV IAPs with RF legs would provide the commonality ATC needs at very busy airports.
RNP AR has been terribily over "installed" in the U.S. and that continues because of programs and goals to be met by desk pilots.
In the US, it has been difficult for the airlines. Many of them spent quite a bit of money getting equipped, certified, and trained, only to find out they seldom get to use RNP. Just as with alot of the CATIII ILS, the airlines are letting the calibration, certs, and recency expire, to save money on costs.
If the FAA would get off the dime about letting non-astronauts fly RF legs, than ordinary RNAV IAPs with RF legs would provide the commonality ATC needs at very busy airports.
RNP AR has been terribily over "installed" in the U.S. and that continues because of programs and goals to be met by desk pilots.
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terspter,
Completely agree...
the FAA went for quantity, not quality.
The concept and reliance on idle descent as a selling tool, alleged fuel and track mile savings was a big mistake, when the airline figured out it didnt save any fuel, and RNP vs non-RNP traffic was not easily blended with current ATC toolset.
SW spent quite a bit of money upgrading their fleet, training, and the OpSpec took about 3 years to get...all that a no place to go.
All that is really necessary is to install the standard T" or "Y" configuration, use 4 mile TF legs instead of 5, then transition to 4nm radius RF turns once the pattern is established.
Simple, effective, straightforward for cert and application.
Completely agree...
the FAA went for quantity, not quality.
The concept and reliance on idle descent as a selling tool, alleged fuel and track mile savings was a big mistake, when the airline figured out it didnt save any fuel, and RNP vs non-RNP traffic was not easily blended with current ATC toolset.
SW spent quite a bit of money upgrading their fleet, training, and the OpSpec took about 3 years to get...all that a no place to go.
All that is really necessary is to install the standard T" or "Y" configuration, use 4 mile TF legs instead of 5, then transition to 4nm radius RF turns once the pattern is established.
Simple, effective, straightforward for cert and application.
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All that is really necessary is to install the standard T" or "Y" configuration, use 4 mile TF legs instead of 5, then transition to 4nm radius RF turns once the pattern is established.
RF legs are permitted but they must terminate not less than 2 miles prior to the FAA. But, the FAA has yet to approve avionics (other than for RNP AR) for RF legs.
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54A?
what is that approved for?
I am an ops guy and design what works, not what any formula based criteria conjures up.
If you mean the FAF, that is also incorrect. There are several methods of termination of RF turns...related to a stabilized approach. One can have a FRP at 15 or 30 seconds before the DA, or by 500 feet FRP.
(FRP =final roll point)
what is that approved for?
I am an ops guy and design what works, not what any formula based criteria conjures up.
If you mean the FAF, that is also incorrect. There are several methods of termination of RF turns...related to a stabilized approach. One can have a FRP at 15 or 30 seconds before the DA, or by 500 feet FRP.
(FRP =final roll point)
Last edited by FlightPathOBN; 24th Jul 2012 at 00:08. Reason: added def FRP
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FlightPathOBN:
It is approved and required for U.S. RNAV IAPs other than RNP AR.
I am sorry, I thought you were a procedures designer.
No wonder you have issues with FAA approvals since you view their current non-RNP-AR criteria order with apparent contempt.
54A?
what is that approved for?
I am an ops guy and design what works, not what any formula based criteria conjures up.
what is that approved for?
I am an ops guy and design what works, not what any formula based criteria conjures up.
I am sorry, I thought you were a procedures designer.
No wonder you have issues with FAA approvals since you view their current non-RNP-AR criteria order with apparent contempt.
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Ok, here's the answer
The HK authorities just need to see a copy of our Company Ops Spec which says our local authority approves the company to operate RNP 1 SID's with an RF Leg. We obviously don't have this yet because there have never been such a Nav Spec requirement in the past. I have shown our authority that aircraft are capable of such a procedure and they are happy. Just a paper work exercise really.
The new 4th Edition of the ICAO PBN Manual (doc 9613) also deals with this issue. Expect more of these types of procedure in the future, they make a lot of sense in busy airspace.
DH
The HK authorities just need to see a copy of our Company Ops Spec which says our local authority approves the company to operate RNP 1 SID's with an RF Leg. We obviously don't have this yet because there have never been such a Nav Spec requirement in the past. I have shown our authority that aircraft are capable of such a procedure and they are happy. Just a paper work exercise really.
The new 4th Edition of the ICAO PBN Manual (doc 9613) also deals with this issue. Expect more of these types of procedure in the future, they make a lot of sense in busy airspace.
DH
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divinehover:
The FAA is presently in coordination with the first STAR with an RF leg. The process is not going smoothly, however. Not the least of all, the TRACON is having hissy fits about it:
The new 4th Edition of the ICAO PBN Manual (doc 9613) also deals with this issue. Expect more of these types of procedure in the future, they make a lot of sense in busy airspace.
Why does the chart show SADDE at a mandatory 250K, but the route description says cross SADDE at 210K?
(edit: the 210 would appear to be the error since SMO requires a mandatory 230K)
(edit: the 210 would appear to be the error since SMO requires a mandatory 230K)
Last edited by OK465; 19th Aug 2012 at 15:13. Reason: noted
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How did you come to that conclusion?
There are hundreds of procedures with speed restrictions on waypoints.
I have several approach procedures with a waypoint at FL10, with a speed restriction of 250kts, a waypoint at 5000 with a restriction of 210, and a waypoint at 3000 with a speed restriction of 180kts.
(note the 'at' for altitude, not 'at or above')
If you set a speed restriction on a waypoint, it will be 'at', crossing that waypoint, not 'at or below'...
There are several procedures with the A320, with a Thales box, where you have to set the waypoints to 'at', or the ac will porpoise down to the next 'at or above' waypoint.
If no speed restrictions are placed on a waypoint, the speeds will default to the alt/speed settings in the box such as 250kts, at or below 10,000 ft.
There are hundreds of procedures with speed restrictions on waypoints.
I have several approach procedures with a waypoint at FL10, with a speed restriction of 250kts, a waypoint at 5000 with a restriction of 210, and a waypoint at 3000 with a speed restriction of 180kts.
(note the 'at' for altitude, not 'at or above')
If you set a speed restriction on a waypoint, it will be 'at', crossing that waypoint, not 'at or below'...
There are several procedures with the A320, with a Thales box, where you have to set the waypoints to 'at', or the ac will porpoise down to the next 'at or above' waypoint.
If no speed restrictions are placed on a waypoint, the speeds will default to the alt/speed settings in the box such as 250kts, at or below 10,000 ft.
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OK,
I see what you are saying, and yes, depending on the ac, and software version, there can be these issues, but these issues can be very variant/box specific, not simply Boeing or Airbus.
There is some coding tricks that I have used to get around some of these issues, but many times you just cant fight the depth of the box...
it was quite the surprise to see that the Smiths box on the NG would not accept an airport elevation over 10,000 feet, and how difficult it was to finally get that to work...
the further we get into these boxes, the more difficult it seems to become, and these issues certainly makes automating CDA, idle descent, TOD, and trajectory management difficult, if not near impossible to achieve...
(and they wonder why a public RNP procedure is so difficult to design)
I see what you are saying, and yes, depending on the ac, and software version, there can be these issues, but these issues can be very variant/box specific, not simply Boeing or Airbus.
There is some coding tricks that I have used to get around some of these issues, but many times you just cant fight the depth of the box...
it was quite the surprise to see that the Smiths box on the NG would not accept an airport elevation over 10,000 feet, and how difficult it was to finally get that to work...
the further we get into these boxes, the more difficult it seems to become, and these issues certainly makes automating CDA, idle descent, TOD, and trajectory management difficult, if not near impossible to achieve...
(and they wonder why a public RNP procedure is so difficult to design)
Last edited by FlightPathOBN; 20th Aug 2012 at 20:07.
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FlightPathOBN:
Those sound like issues with design of special RNP AR IAPs for a particular operator.
The only deference the FAA has made to avionics in the design of public RNP AR IAPs (and we have a whole lot of them now) is not less than 50 seconds of flight between the FROP and the DA to accommodate the AB, and that is only if the missed approach is an RNP missed approach (less than RNP 1.0). Otherwise it is not less than 15 seconds. This is to accommodate transition to GA mode. The only other accommodation, and it is very broad, is that an IRU is not required for RNP AR IAPs of not less than 0.30, and without missed approaches of less than RNP 1.0.
It's up to the airframe OEMs to address the multitude of specific avionics issues in order to obtain RNP approach level approval.
Difficult to obtain that approval and for the operator to validate the RNP AR database? Yes.
Difficult to design public RNP AR IAPs? No, at least not in the United States. The only major impediment to public design is ATC and impossible terrain at a very few locations.
the further we get into these boxes, the more difficult it seems to become, and these issues certainly makes automating CDA, idle descent, TOD, and trajectory management difficult, if not near impossible to achieve...
(and they wonder why a public RNP procedure is so difficult to design)
(and they wonder why a public RNP procedure is so difficult to design)
The only deference the FAA has made to avionics in the design of public RNP AR IAPs (and we have a whole lot of them now) is not less than 50 seconds of flight between the FROP and the DA to accommodate the AB, and that is only if the missed approach is an RNP missed approach (less than RNP 1.0). Otherwise it is not less than 15 seconds. This is to accommodate transition to GA mode. The only other accommodation, and it is very broad, is that an IRU is not required for RNP AR IAPs of not less than 0.30, and without missed approaches of less than RNP 1.0.
It's up to the airframe OEMs to address the multitude of specific avionics issues in order to obtain RNP approach level approval.
Difficult to obtain that approval and for the operator to validate the RNP AR database? Yes.
Difficult to design public RNP AR IAPs? No, at least not in the United States. The only major impediment to public design is ATC and impossible terrain at a very few locations.
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Procedures are not difficult to design, but procedures that actually work are.
That is why there are such the issues with ATC, RNP with multi-variants was never envisioned in the criteria, as it is built around a 737NG with a Smiths box.
As noted by OK, the boxes act differently, so will the procedures. If you try to put an A320 with a Thales box, on the same procedure that was for a 737NG with a SMiths box, it may not, and most times, does not work. That is why one cannot use the criteria, or the spreadsheets with anything but limited success..hell, they have few turns because TARGETS cant design a turn correctly, the wrong great circle algorithm was used, at least they can use SAAR-Pro, or RNAV-Pro, then dump the results into TARGETS for the database.
Then you assume that you are the only ac in the sky, how do multiple ac of different types, use the procedure, and provide ATC the ability to control the ac?
When you design an multi-variant RNP approach procedure, with a queue ranging from 737, 320, E90, 744, and A380, with Smith, HW, and Thales FMC, and keep them at radar or wake sep, with ATC guidance...
then you will understand what difficult is.
That is why there are such the issues with ATC, RNP with multi-variants was never envisioned in the criteria, as it is built around a 737NG with a Smiths box.
As noted by OK, the boxes act differently, so will the procedures. If you try to put an A320 with a Thales box, on the same procedure that was for a 737NG with a SMiths box, it may not, and most times, does not work. That is why one cannot use the criteria, or the spreadsheets with anything but limited success..hell, they have few turns because TARGETS cant design a turn correctly, the wrong great circle algorithm was used, at least they can use SAAR-Pro, or RNAV-Pro, then dump the results into TARGETS for the database.
Then you assume that you are the only ac in the sky, how do multiple ac of different types, use the procedure, and provide ATC the ability to control the ac?
When you design an multi-variant RNP approach procedure, with a queue ranging from 737, 320, E90, 744, and A380, with Smith, HW, and Thales FMC, and keep them at radar or wake sep, with ATC guidance...
then you will understand what difficult is.
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That's why we have the database verification and flyability requirements set forth in AC90-101A.
If the procedure doesn't pass muster with a particular airframe/FMS combination, it cannot be loaded in that airframe/FMS combination, at least not in the U.S.
If the procedure doesn't pass muster with a particular airframe/FMS combination, it cannot be loaded in that airframe/FMS combination, at least not in the U.S.
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Meeting the criteria and flyability have only so much to do with ATC operations.
While the ac may perform just fine, the procedure in itself is worthless if ATC cannot manage it.
As an example, the 737-800 in the US is a CAT C ac, with FAS of 140kts. According to the criteria, the entire final approach segment must be flown at a max speed of 140 kts. If there is a turn to final, the max speed of that turn is 140 kts.
With a 5 to 7 mile final approach segment, how often do you see a 737 anything, at 140 kts 5 nm out? Add a turn, and you have the 737 or CAT C ac at 140 kts for 10 nm out.
Allegedly, these aircraft are all on idle descent, so the 320, 734, 738, 744, and others, are all happily gliding down on a 3 degree glidepath, and ATC is supposed to keep them all properly separated, and somehow try to optimize the spacings and queue?
The reality is that if the criteria pumps out procedures that ATC, with current tool sets, cannot manage, then the procedures are rubbish...
While the ac may perform just fine, the procedure in itself is worthless if ATC cannot manage it.
As an example, the 737-800 in the US is a CAT C ac, with FAS of 140kts. According to the criteria, the entire final approach segment must be flown at a max speed of 140 kts. If there is a turn to final, the max speed of that turn is 140 kts.
With a 5 to 7 mile final approach segment, how often do you see a 737 anything, at 140 kts 5 nm out? Add a turn, and you have the 737 or CAT C ac at 140 kts for 10 nm out.
Allegedly, these aircraft are all on idle descent, so the 320, 734, 738, 744, and others, are all happily gliding down on a 3 degree glidepath, and ATC is supposed to keep them all properly separated, and somehow try to optimize the spacings and queue?
The reality is that if the criteria pumps out procedures that ATC, with current tool sets, cannot manage, then the procedures are rubbish...
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FlightPathOBN:
Two different issues. I agreed with you on the ATC aspects several messages ago. RNP AR was intended to solve difficult terrain issues and typically at airports where ATC couldn't care less such as Rifle, Colorado and Bishop, California.
But, along comes an airline with more money than insight and thinks they will save a few gallons of Jet A every leg with RNP AR at high traffic locations.
Now that it is obvious even to them that it isn't working they are whinning to the highest levels of the FAA. That, of course, will get them nowhere.
I believe that very limited use of RF legs on SIDs and STARs will eventually prove to be useful, once most of the operators, including business aviation, are approved for non-RNP AR RF legs. But, that is it. Forget RNP AR IAPs at high traffic locations except special cases like down the river at KDCA.
Two different issues. I agreed with you on the ATC aspects several messages ago. RNP AR was intended to solve difficult terrain issues and typically at airports where ATC couldn't care less such as Rifle, Colorado and Bishop, California.
But, along comes an airline with more money than insight and thinks they will save a few gallons of Jet A every leg with RNP AR at high traffic locations.
Now that it is obvious even to them that it isn't working they are whinning to the highest levels of the FAA. That, of course, will get them nowhere.
I believe that very limited use of RF legs on SIDs and STARs will eventually prove to be useful, once most of the operators, including business aviation, are approved for non-RNP AR RF legs. But, that is it. Forget RNP AR IAPs at high traffic locations except special cases like down the river at KDCA.
