Question on KASE LOC/DME-E in Aspen

[lancie00]

I just took a quiz on Boldmethod about this approach. The question was "If you're equipped with 1 GPS receiver and 1 VHF nav receiver in your plane, can you fly the approach?" Their answer is no because the plate requires "dual VHF navigation receivers". I thought that GPS could be used in place of a nav receiver? Am I missing something here? And if so, why would they require 2 VHF receivers vs allowing a GPS?

 

[dtuuri]

I just took a quiz on Boldmethod about this approach. The question was "If you're equipped with 1 GPS receiver and 1 VHF nav receiver in your plane, can you fly the approach?" Their answer is no because the plate requires "dual VHF navigation receivers". I thought that GPS could be used in place of a nav receiver? Am I missing something here? And if so, why would they require 2 VHF receivers vs allowing a GPS?

My guess is so you don't have to switch frequencies at the missed approach point in order to fly the missed approach back course. That would be a pretty workload intense time to set up and identify a new course.

 

[midlifeflyer]

I just took a quiz on Boldmethod about this approach. The question was "If you're equipped with 1 GPS receiver and 1 VHF nav receiver in your plane, can you fly the approach?" Their answer is no because the plate requires "dual VHF navigation receivers". I thought that GPS could be used in place of a nav receiver? Am I missing something here? And if so, why would they require 2 VHF receivers vs allowing a GPS?

What you may be missing is that GPS may be used in place of most NAVs, but not a localizer.

That, plus Dave's comment about switching frequencies. The missed at Aspen is a back course off a different localizer than the one you are flying inbound. If you look at this approach, you will see the missed is downright deadly. There is no time to be fumbling with a frequency change.

 

[BillTIZ]

Also on the missed, you are tracking a LOC back course outbound on one radio and need to pick up the DBL 244R outbound on the second radio. I will agree that an outbound course from DBL could be set up on the GPS.

 

[IK04]

Simple. It is the only way to fix LINDZ, part of the missed approach.

 

[midlifeflyer]

Simple. It is the only way to fix LINDZ, part of the missed approach.

Why couldn't you identify LINDZ with GPS?

 

[IK04]

Why couldn't you identify LINDZ with GPS?

Because it is not allowed by the procedure.


Maybe someday the FAA will flight test the fix as a GPS derived fix and create a new AIP to reflect it.

There is a new type of AIP called a "hybrid" that uses GPS fixes for everything except the final approach course, which is a LOC/BC or LDA.

 

[dmspilot]

Because it is not allowed by the procedure.

Where does it say that?

 

[IK04]

Where does it say that?

"DUAL VHF NAVIGATION RECEIVERS REQUIRED"

Then, in the missed approach instructions:

"...and on I-PKN Localizer NW course (303) to LINDZ INT/DBL 12.6 DME and on DBL VOR/DME R-244 to GLENO INT/DBL 22.7 DME and hold."

The DME requirement is stated in the name of the procedure (LOC/DME). Both LINDZ and GLENO are described as "INT" intersections, not GPS fixes.


Here is the data from the FAA aeronautical fixes publication:

Information on fix LINDZ
Identifier: LINDZ
Name: LINDZ
Location: 39-23-19.550N 107-09-28.500W
Navaid radial/DME: DBLr244.17/12.61
SXWr196.28
Fix use: Reporting point
Published: yes
Charts: ENROUTE LOW
IAP
SID

No mention of it being a GPS fix and it was last updated 07/31/2012.

Now, as we all know, (right?) You can fly your GPS equipped, moving-map-having display with the magenta line and even couple your flight director/FMS to it, but you MUST have the dual VHF nav receivers tuned and identified and set to the appropriate courses. Otherwise you are not legally flying the procedure as published. Really.

Word.

 

[midlifeflyer]

Where does it say that?

It doesn't.

"DUAL VHF NAVIGATION RECEIVERS REQUIRED"

Then, in the missed approach instructions:

"...and on I-PKN Localizer NW course (303) to LINDZ INT/DBL 12.6 DME and on DBL VOR/DME R-244 to GLENO INT/DBL 22.7 DME and hold."

The DME requirement is stated in the name of the procedure (LOC/DME). Both LINDZ and GLENO are described as "INT" intersections, not GPS fixes.


Here is the data from the FAA aeronautical fixes publication:

Information on fix LINDZ
Identifier: LINDZ
Name: LINDZ
Location: 39-23-19.550N 107-09-28.500W
Navaid radial/DME: DBLr244.17/12.61
SXWr196.28
Fix use: Reporting point
Published: yes
Charts: ENROUTE LOW
IAP
SID

No mention of it being a GPS fix and it was last updated 07/31/2012.

Now, as we all know, (right?) You can fly your GPS equipped, moving-map-having display with the magenta line and even couple your flight director/FMS to it, but you MUST have the dual VHF nav receivers tuned and identified and set to the appropriate courses. Otherwise you are not legally flying the procedure as published. Really.

Word.

I don't know that. You can't fly the magenta line with your FMS coupled to the GPS on this one. You cannot use GPS in lieu of a localizer course. If you look at the advisory which allows use of GPS as primary so long as "raw data" is available it specifically says, not with a LOC course.

We clearly read the requirement differently. You see a general GPS not authorized to substitute for any portion of the approach. I see the general limitation against the use of GPS to substitute for a localizer (WAG: likely because there's no requirement your GPS has WAAS, which is the only way it could theoretically substitute for a LOC; not sure if it's related, but I also notice the GPS approach has no LP or LPV minimums).

Hopefully, @aterpster will notice the thread and educate all of us,

 

[Sluggo63]

The DME requirement is stated in the name of the procedure (LOC/DME). Both LINDZ and GLENO are described as "INT" intersections, not GPS fixes.

The DME requirement stated in the name of the procedure (LOC/DME) is only what is required to fly the final portion, and has no bearing on what you may or may not need to fly the missed approach.

 

[IK04]

The DME requirement stated in the name of the procedure (LOC/DME) is only what is required to fly the final portion, and has no bearing on what you may or may not need to fly the missed approach.

Yep. Those were two completely separate statements and not related to each other.

 

[midlifeflyer]

Yep. Those were two completely separate statements and not related to each other.

Agree with you on that part.

No mention of it being a GPS fix and it was last updated 07/31/2012.

I got curious about your idea that intersections not specifically defined as GPS waypoints in the FAA database may not be identified by GPS. Any other examples? I've been looking in the database at known GPS waypoints (including ones on GPS approaches) and don't see any which have any mention of them being GPS fixes. Do have any examples of fixes which do mention GPS in the database?

 

[IK04]

It doesn't.

I don't know that. You can't fly the magenta line with your FMS coupled to the GPS on this one. You cannot use GPS in lieu of a localizer course. If you look at the advisory which allows use of GPS as primary so long as "raw data" is available it specifically says, not with a LOC course.

That is not at all what I said. FOR SITUATIONAL AWARENESS ONLY, you may certainly fly the magenta line, as long as your PRIMARY navigator, VOR/VOR in this case, is tuned, identified and set to the correct course to be flown (on the OBS x2, or HSI) for that segment of the approach. The GPS is doing NOTHING with regard to the Approach procedure.

It would be the same as coupling the autopilot to your heading and using it to manually fly the approach IAW the displayed navigation source, the VOR/LOC in this case. The GPS is not being used to navigate the legs of the procedure or the localizer. You could also hand-fly the whole procedure as long as you are using the HSI to navigate and only referring to the map and magenta line for SA only.

You could also couple your autopilot to the HSI/CDI/OBS course and fly the approach right up to the missed approach, then switch to heading, and then back to VOR once you are established on the 244 radial outbound.

Of course, this only applies to part 91 ops, since a 135/121 operator will have specific approved procedures for use of the autopilot.

Every aircraft/avionics manufacturer does thing slightly differently with regard to what they call an FMS, a Flight Director and an autopilot. I prefer a moving map with the legs of an approach depicted by a line and a flight director that simply gives you attitude cues to stay on course. I will use all the electronic tools available to me to reduce workload and enhance situational awareness and avoid spatial disorientation.

Bottom line: The GPS navigator is not being used to navigate any portion of the approach procedure. Forget any reference to autopilot/FMS to make it simpler to understand.

 

[midlifeflyer]

That is not at all what I said. FOR SITUATIONAL AWARENESS ONLY, you may certainly fly the magenta line, as long as your PRIMARY navigator, VOR/VOR in this case, is tuned, identified and set to the correct course to be flown (on the OBS x2, or HSI) for that segment of the approach. The GPS is doing NOTHING with regard to the Approach procedure.

It would be the same as coupling the autopilot to your heading and using it to manually fly the approach IAW the displayed navigation source, the VOR/LOC in this case. The GPS is not being used to navigate the legs of the procedure or the localizer. You could also hand-fly the whole procedure as long as you are using the HSI to navigate and only referring to the map and magenta line for SA only.

You could also couple your autopilot to the HSI/CDI/OBS course and fly the approach right up to the missed approach, then switch to heading, and then back to VOR once you are established on the 244 radial outbound.

Of course, this only applies to part 91 ops, since a 135/121 operator will have specific approved procedures for use of the autopilot.

Every aircraft/avionics manufacturer does thing slightly differently with regard to what they call an FMS, a Flight Director and an autopilot. I prefer a moving map with the legs of an approach depicted by a line and a flight director that simply gives you attitude cues to stay on course. I will use all the electronic tools available to me to reduce workload and enhance situational awareness and avoid spatial disorientation.

Bottom line: The GPS navigator is not being used to navigate any portion of the approach procedure. Forget any reference to autopilot/FMS to make it simpler to understand.

I obviously misunderstood the part of your comment about using the FMS.

 

[IK04]

I am still looking for the reference for the codes used to identify fixes. In the mean time here are two screenshots, one of LINDZ and the other is a known GPS fix taken from a SID:


LINDZ is shown as a "RP" fix and WALTU is a "WP" fix.

WALTU is obviously a "waypoint," so it is a WP.

LINDZ is defined by the intersection of the two radials shown. "RP" must refer to a RNAV Point.

Both fixes are searchable in the database, so in the absence of a graphical depiction on a chart, this seems to be the only place to know this.

That's all I've got at this point. Too much research for one night!

 

[dtuuri]

Simple. It is the only way to fix LINDZ, part of the missed approach.

I'm not buying this, sorry. I've read your arguments through post #16, but IMO two VORs aren't required to find LINDZ. If they were, all those intersection holds I had to do with one VOR back when I got my instrument rating were strictly sadistic pleasures on the part of my CFI. GPS, according to AIM para 1-2-3.c.1., can be used:

"Determine aircraft position relative to, or distance from a VOR (see NOTE 6 below), TACAN, NDB, compass locator, DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course."​

Note #2 goes on to say:

"These operations do not include lateral navigation on localizer−based
courses (including localizer back−course guidance) without reference to raw localizer data."
​

I would have to conclude LINDZ can be identified by GPS while navigating the back-course.

 

[Clip4]

It doesn't.

I don't know that. You can't fly the magenta line with your FMS coupled to the GPS on this one. You cannot use GPS in lieu of a localizer course. If you look at the advisory which allows use of GPS as primary so long as "raw data" is available it specifically says, not with a LOC course.

We clearly read the requirement differently. You see a general GPS not authorized to substitute for any portion of the approach. I see the general limitation against the use of GPS to substitute for a localizer (WAG: likely because there's no requirement your GPS has WAAS, which is the only way it could theoretically substitute for a LOC; not sure if it's related, but I also notice the GPS approach has no LP or LPV minimums).

Hopefully, @aterpster will notice the thread and educate all of us,

The reason I suspect you cannot use GPS for the missed is the sensitivity swithcing in the navigator. The box does not in LP mode.

 

[MauleSkinner]

Note that the VOR DME C approach has the same requirement.

I'd suspect the transition from the final approach course to the missed approach back course is faster than some magical threshold time it takes to tune and identify the BC for the missed.

 

[midlifeflyer]

Note that the VOR DME C approach has the same requirement.

I'd suspect the transition from the final approach course to the missed approach back course is faster than some magical threshold time it takes to tune and identify the BC for the missed.

If you look at the missed and the terrain, you can actually see that. There is no straight ahead climb before turning and it's pretty narrow. You need to get on that back course localizer immediately or they will be picking up the pieces. It has happened.

...and the RNAV-F follows the same missed course, even to the extent if using those LINDZ and GLENO waypoints, but as a pure RNAV procedure not requiring the LOC, there's no dual VHF requirement.

 

[midlifeflyer]

The reason I suspect you cannot use GPS for the missed is the sensitivity swithcing in the navigator. The box does not in LP mode.

The GPS approach uses GPS firbthe same missed course.

 

[aterpster]

What you may be missing is that GPS may be used in place of most NAVs, but not a localizer.

That, plus Dave's comment about switching frequencies. The missed at Aspen is a back course off a different localizer than the one you are flying inbound. If you look at this approach, you will see the missed is downright deadly. There is no time to be fumbling with a frequency change.

This is not settled "science." No doubt you need to use the 111.15 localizer to fly the final approach segment, but it is debatable about the missed approach 108.5 missed approach localizer. The 108.5 localizer was installed to provide PCG after turn completion, because a DR missed approach would include the very high terrain to the west (14,158'), which would cause the missed approach to have a prohibitively high climb gradient, given the existing MDA. A VOR couldn't be use at the site of the 108.5 localizer because of an inadequate ground plane. Having said that, the TERPs missed approach protected area is predicated on VOR standards upon completion of turn. Commercial operators that use ASE on a regular basis and are RNP APCH compliant, use RNAV for the missed approach.

That missed approach localizer was installed before GPS RNAV was even a possibility. Plus, most of the commercial operators have GPS-updated current technology triple IRUs.

 

[aterpster]

The GPS approach uses GPS firbthe same missed course.

Makes the case, doesn't it. Note the 190 KIAS limit on the GPS missed approach. That's because Order 8260.58A criteria are used instead of TERPs.

 

[dmspilot]

"DUAL VHF NAVIGATION RECEIVERS REQUIRED"

Then, in the missed approach instructions:

"...and on I-PKN Localizer NW course (303) to LINDZ INT/DBL 12.6 DME and on DBL VOR/DME R-244 to GLENO INT/DBL 22.7 DME and hold."

The DME requirement is stated in the name of the procedure (LOC/DME). Both LINDZ and GLENO are described as "INT" intersections, not GPS fixes.


Here is the data from the FAA aeronautical fixes publication:

Information on fix LINDZ
Identifier: LINDZ
Name: LINDZ
Location: 39-23-19.550N 107-09-28.500W
Navaid radial/DME: DBLr244.17/12.61
SXWr196.28
Fix use: Reporting point
Published: yes
Charts: ENROUTE LOW
IAP
SID

No mention of it being a GPS fix and it was last updated 07/31/2012.

Now, as we all know, (right?) You can fly your GPS equipped, moving-map-having display with the magenta line and even couple your flight director/FMS to it, but you MUST have the dual VHF nav receivers tuned and identified and set to the appropriate courses. Otherwise you are not legally flying the procedure as published. Really.

Word.

Literally nothing you wrote is evidence that you can't identify LINDZ with GPS. Really. You're grasping at straws.

Your points are all addressed by AIM 1-2-3.

Both LINDZ and GLENO are described as "INT" intersections, not GPS fixes.

It doesn't matter that it's "not a GPS fix". AIM 1-2-3(c)(1): A suitable RNAV system may be used to determine "aircraft position relative to, or distance from a VOR [including VOR, VOR/DME, and VORTAC facilities], TACAN, NDB, compass locator, DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course."

The DME requirement is stated in the name of the procedure (LOC/DME).

And 1-2-3(c) Note 1: "The allowances described in this section apply even when a facility is identified as required on a procedure."

Here is the data from the FAA aeronautical fixes publication

You're telling me I need to look up every fix in the FAA database, and if it's a "Waypoint" I can use GPS and if it's a "Reporting Point" then I can't use GPS? Are you for real?

You are making stuff up.

 

[midlifeflyer]

This is not settled "science." No doubt you need to use the 111.15 localizer to fly the final approach segment, but it is debatable about the missed approach 108.5 missed approach localizer. The 108.5 localizer was installed to provide PCG after turn completion, because a DR missed approach would include the very high terrain to the west (14,158'), which would cause the missed approach to have a prohibitively high climb gradient, given the existing MDA. A VOR couldn't be use at the site of the 108.5 localizer because of an inadequate ground plane. Having said that, the TERPs missed approach protected area is predicated on VOR standards upon completion of turn. Commercial operators that use ASE on a regular basis and are RNP APCH compliant, use RNAV for the missed approach.

That missed approach localizer was installed before GPS RNAV was even a possibility. Plus, most of the commercial operators have GPS-updated current technology triple IRUs.

Thanks Wally.

Aren't there also two "special" instrument approaches for Aspen - a LOC/DME 15 and an RNAV 15 - requiring specific crew training and qualification? Wouldn't those be the ones most commercial operators are using? I've found references to the training courses, but not copies of the plates, which are apparently only available to those who have qualified.

 

[MauleSkinner]

Thanks Wally.

Aren't there also two "special" instrument approaches for Aspen - a LOC/DME 15 and an RNAV 15 - requiring specific crew training and qualification? Wouldn't those be the ones most commercial operators are using? I've found references to the training courses, but not copies of the plates, which are apparently only available to those who have qualified.

I believe the plates are owned by the operator(s) in question, but Wally would know that better than me.

The umbrella of "commercial operators", of course, includes Part 135 operators who don't have access and/or training, and "we" are flying the missed using GPS navigation.

 

[aterpster]

Thanks Wally.

Aren't there also two "special" instrument approaches for Aspen - a LOC/DME 15 and an RNAV 15 - requiring specific crew training and qualification? Wouldn't those be the ones most commercial operators are using? I've found references to the training courses, but not copies of the plates, which are apparently only available to those who have qualified.

I have them. The LOC/DME 15 uses the same localizer missed approach and the RNAV 15 uses the same RNAV missed approach as the public procedure.

 

[aterpster]

I believe the plates are owned by the operator(s) in question, but Wally would know that better than me.

The umbrella of "commercial operators", of course, includes Part 135 operators who don't have access and/or training, and "we" are flying the missed using GPS navigation.

The charts are owned by the operators. The source is owned by the FAA and the FAA must authorize its use. In some cases, such as Alaska Airlines, they develop their special procedures in house. So, they own both the charts and the source.

 

[dtuuri]

This is not settled "science." No doubt you need to use the 111.15 localizer to fly the final approach segment, but it is debatable about the missed approach 108.5 missed approach localizer.

The missed approach instructions are... "MISSED APPROACH: Climbing right turn to 14000 on heading 300° and on I-PKN localizer NW course (303°) to LINDZ INT/DBL 12.6 DME..." so that doesn't sound "debatable" to me, especially since the 190 KIAS speed restriction doesn't appear on the LOC/DME-E chart.

 

[dtuuri]

... "we" are flying the missed using GPS navigation.

On the LOC/DME-E approach??

 

[midlifeflyer]

The missed approach instructions are... "MISSED APPROACH: Climbing right turn to 14000 on heading 300° and on I-PKN localizer NW course (303°) to LINDZ INT/DBL 12.6 DME..." so that doesn't sound "debatable" to me, especially since the 190 KIAS speed restriction doesn't appear on the LOC/DME-E chart.

I'm pretty sure based on the context, that Wally's "debatable" is referring to the use of GPS to track the backcourse localizer for the missed.

My view based on the AIM discussion at 1-2-3, "Use of Suitable Area Navigation (RNAV) Systems on Conventional Procedures and Routes" and related guidance is that substitution in all permitted instances is limited to VOR, DME, TACAN, and NDB, but not LOC and it's derivatives like LDA and SDF. I think Wally is saying that's not as clear as I think it is and is pointing to the fact that the RNAV missed is similar to support the idea it doesn't really matter.

 

[midlifeflyer]

You're telling me I need to look up every fix in the FAA database, and if it's a "Waypoint" I can use GPS and if it's a "Reporting Point" then I can't use GPS? Are you for real?

You are making stuff up.

Don't get too excited. Yes, he made that up and he's incorrect. As already pointed out, there is not identification of "GPS waypoint" in the FAA waypoint database. Just latitude/longitude and radial/distance is applicable. Plus the two fixes on the LOC approach he pointed to as not permitting identification by GPS are on the RNAV (GPS) approach.

But I'm sure there is not one of us here who has read part of something and then, based on an incorrect assumption or two, thought it was the whole thing.

 

[MauleSkinner]

On the LOC/DME-E approach??

Yes...as Wally said, the prohibition would be debatable based on the protected airspace.

 

[MauleSkinner]

The missed approach instructions are... "MISSED APPROACH: Climbing right turn to 14000 on heading 300° and on I-PKN localizer NW course (303°) to LINDZ INT/DBL 12.6 DME..." so that doesn't sound "debatable" to me, especially since the 190 KIAS speed restriction doesn't appear on the LOC/DME-E chart.

Note Wally's explanation for the speed restriction...it has nothing to do with the nav source, but a different protected airspace criteria.

 

[dtuuri]

Note Wally's explanation for the speed restriction...it has nothing to do with the nav source, but a different protected airspace criteria.

I'm not sure I understand then. It makes sense to me GPS equipment navigating to LINDZ could stray too far west during the turn without the 190 KIAS restriction. With the back course for positive course guidance, the speed wouldn't matter. I remember departing Palwaukee toward O'Hare there was such a speed restriction too, as you made your turn northbound to avoid their airspace..

 

[aterpster]

I'm not sure I understand then. It makes sense to me GPS equipment navigating to LINDZ could stray too far west during the turn without the 190 KIAS restriction. With the back course for positive course guidance, the speed wouldn't matter. I remember departing Palwaukee toward O'Hare there was such a speed restriction too, as you made your turn northbound to avoid their airspace..

Yes indeed. It was placed there at the request of ATC, not because of obstacles.

At ASE most jet missed approaches are done at 200 knots, or less until establish NW bound. The RNAV procedure requires a max of 190 knots all the way to LINDZ for no good reason, unless ATC requested it for speed control.

And, as to the missed approach LDA, if some hot jock accelerated to 250, or even greater, he would blow right through the LDA.

 

[Larry in TN]

There is no such thing as a "GPS waypoint", only "waypoints". There are waypoints, fixes, intersections, etc., each of which can be identified by a number of different navigation systems.

Plus, most of the commercial operators have GPS-updated current technology triple IRUs.

I've never been to ASE but I think a lot of the airline traffic there is flown by the CRJ-700. It doesn't have IRUs. Just single or dual FMS with DME/DME/GPS updating. Wouldn't be surprised if a lot of the pilots flying them don't understand what the DME/DME portion of them actually does.

 

[IK04]

You're telling me I need to look up every fix in the FAA database, and if it's a "Waypoint" I can use GPS and if it's a "Reporting Point" then I can't use GPS? Are you for real?

You are making stuff up.

I was pointing out how the fix was derived. If it sounded like I was saying you can't use it with GPS, that's not what I meant. It can be used with ANY RNAV system, such as DME/DME or INU- based systems.

On THIS approach, the missed approach instructions are to follow the LOC BC to the intersection. That explains the requirement for dual VOR nav systems. If you want to navigate there using an RNAV system, go ahead. The AIM 1-2-3 use of GPS/RNAV allows for that. I'm saying the route to the missed approach fix is defined for Positive Course Guidance by the localizer and the VOR intersection.

 

[dmspilot]

If it sounded like I was saying you can't use it with GPS, that's not what I meant.

It didn't "sound" like you said that. You said that:

IK04: "[Having dual VHF receivers] is the only way to fix LINDZ"
midlifeflyer: "Why couldn't you identify LINDZ with GPS?"
IK04: "Because it is not allowed by the procedure."

Your explanation was that DME was in the name of the approach and that LINDZ is not described as a GPS fix in the FAA database.

I was pointing out how the fix was derived.

I must have missed the part where somebody thought LINDZ was a GPS-only fix and needed an explanation that it wasn't.

 

[IK04]

Your explanation was that DME was in the name of the approach and that LINDZ is not described as a GPS fix in the FAA database.

I should have never mentioned DME. It was 3:30 am and I should have gone back to bed...