Intercept Loc Outbound

[aterpster]

SR71:

You and I both know why Jepperson include the note "I-PKN backcourse is normal sensing outbound" on their plates.

They do on several of the departure charts and on one of the two IAP charts. Why not on both of the IAP charts? Both IAPs use the IPKN LOC for their respective missed approach procedures.

And, why does the LOC IAP require "dual VHF navigation receiver" but the VOR IAP does not.

Weird in both cases.

[aterpster]

PBL:

Terpster and Guppy,

I don't want to sidetrack the thread any more than necessary, but your comments on Cali suggest I need to clarify.

Everybody seems to want to select their favorite causal factors for a given accident, and say "it was *really* this". Analysts such as myself list and discuss all of them. If we want to prioritise some for some reason, we then provide our criteria and perform the selection. The paper which I referenced considers broadly speaking the language issues. It does not consider the others (for that, see our full analysis).

I think I covered the significant causes in Post 28 above. Language issues did not excuse that conduct. The verbal exchanges made it seem like the AAL expected the world to have ATC radar services, and that radar controllers are magicans.

Nonetheless, letting an aircraft depart protected airspace in a wild descent is beyond the pale.

[SR71]

aterpster,

That is weird.

I obviously haven't seen the full set of plates.

Having done a short stint working for Jepperson's main competitor as a Small Chart Compiler and cognizant of who actually does this kind of work, maybe the answer to that question is, oversight?

The charts go through various stages of "checking" before final submission and maybe that plate got missed?

In terms of the physics, isn't the main reason for using a backcourse procedure for the MA here, because, tracking with accuracy is most critical early on in the MA procedure where you are close to the ground and when using a beam radiating from the location of the I-PKN, you gain that accuracy where you need it?

If you used a nav aid based on the position of LINDZ the converse is true, with your ability to track accurately getting better the close you are to LINDZ.

[Zeffy]

The full set of FAA charts can be found here (click the desired effective date and search "ASE").

The fact that FAA and Jepp seem to contain the same discrepancies would tend to indicate that those discrepancies are embodied in government source.

[forget]

Having done a short stint working for Jepperson's main competitor as a Small Chart Compiler and cognizant of who actually does this kind of work, maybe the answer to that question is, oversight?

Interesting that this badly misused word should come up in a discussion on semantics. You mean supervision - not oversight. And don't go blaming Webster. It's oversight that causes things to be missed.

[aterpster]

SR71:

The charts go through various stages of "checking" before final submission and maybe that plate got missed?

This problem obviously lies with the source. Having said that, Jeppesen used to be better at challenging such discrepencies than they are today. I need supervision, too, I reversed the IAPs in my previous post.

In terms of the physics, isn't the main reason for using a backcourse procedure for the MA here, because, tracking with accuracy is most critical early on in the MA procedure where you are close to the ground and when using a beam radiating from the location of the I-PKN, you gain that accuracy where you need it?

That sums it up. Nothing else would provide the navigation accuracy required to miss some really high terrain during, and just after, that missed approach turn. It is not nearly as critical for the departure procedures.

[SR71]

Interesting that this badly misused word should come up in a discussion on semantics. You mean supervision - not oversight. And don't go blaming Webster. It's oversight that causes things to be missed.

We're a long way from the OP's question but...

Two basic stages (if not more) in chart compilation...

So, perhaps an oversight on the part of the compiler when transcribing the FAA document into the Jepp document (or in this case, from the FAA team actually putting the original document(s) together in the first place?), which, then, at the various stages of quality control/supervision (call it what you want) further up the editorial heirarchy, were also.....what?

So I'm not sure I understand your distinction.

That sums it up. Nothing else would provide the navigation accuracy required to miss some really high terrain during, and just after, that missed approach turn. It is not nearly as critical for the departure procedures.

With this in mind, the VOR procedure at the same field makes a mockery of this type of justification!

Presumably it is rarely flown in comparison to the LOC?

[aterpster]

SR71:

With this in mind, the VOR procedure at the same field makes a mockery of this type of justification!

Presumably it is rarely flown in comparison to the LOC?

I suspect the VOR IAP is flown more because it is authorized for GPS overlay.

I don't follow why you believe the VOR IAP makes a mockery of the missed approach LDA guidance (if that is what you mean).

The valley in which the airport lies has more than adequate room for the intermediate and final segments required for a VOR IAP. The missed approach segment is limiting for both the VOR and LOC IAPs, thus the IPKN LDA guidance is equally critical for both missed approach procedures.

Having said that, in the event of a missed approach folks with RNAV typically fly an RNAV course that overlays the IPKN LDA. Technically, that is not legal, but in practice it works fine.

[SNS3Guppy]

You and I both know why Jepperson do not include the note "If you fly around randomly below MSA IMC, you'll bump into something" on their ASPEN plate.

You and I both know why Jepperson include the note "I-PKN backcourse is normal sensing outbound" on their plates.

I don't presume to know why Jeppesen may include a warning on their chart, but your example is ridiculous. The warning, however tongue-in-cheek you intend to be, is nonsensical, as flying below MSA doesn't guarantee that one will hit something nor does doing so while in instrument meteorological conditions. Accordingly, such a warning would be stupid. Furthermore, as MSA is provided for every chart and is standardized, and the significance thereof fully understood, a nonsensical incorrect note regarding it's application would be superfluous.

NACO publishes the Aspen charts (as does Jeppesen) with a notation on the localizer course because it serves to clarify the procedure and show very plainly what is to be done and what is to be expected. Proper terminology is used, specifying normal sensing vs. reverse sensing. Procedural notes are used on approach, arrival, and departure charts where necessary to clarify the procedure, and that's exactly what is done with the statement "I-PKN backcourse is normal sensing outbound."

Perhaps you know something more about this that you're not telling us? You stated that you and I have a collective knowledge about that statement, and I very much doubt that's true, so if you have additional insight to offer, spit it out. I'm all ears.

With this in mind, the VOR procedure at the same field makes a mockery of this type of justification!

Presumably it is rarely flown in comparison to the LOC?

I've flown the VOR procedure many times at KASE. How, exactly, does it make a mockery of Aterpster's comments?

The localizer approach to the runway at ASE takes place through a different canyon than the departure while following the back course. Furthermore, the canyon and terrain widens and opens up as one departs away from Aspen on the back course, toward Lindz. Aterpster's comments are accurate and correct.

Most operators who fly into Aspen won't fly the approaches if the weather is below Red Table VOR, and won't go in there at night. Night restrictions and circling restrictions took place a few years ago following a well-publicized crash. I've circled there many times in the past, as well as arrived and departed at night, before these changes took place. My personal preference is arriving in the day when I can see the runway from the start of the procedure, and this is how most operators go there, too.

Insofar as your assessment of Aterpster's comments regarding the necessity for the accurate back-course guidance on the missed approach, there's no inconsistency. The VOR and Localizer approaches have different ground tracks, different obstacles on the approach, and different initial altitudes. Whereas the VOR approach begins at the highest terrain, it provides the most accurate guidance closest to that terrain. The localizer approach provides accurate guidance throughout, but most accurate closer to the runway. Both execute their missed approaches at about the same place, using the same procedure, and both utilize the back course for accurate course guidance terrain avoidance during the missed.

In turn, the localizer back course is most accurate near the transmitter, which is where it's closest to the terrain and the most critical. As one climbs out toward LINDZ, one gains terrain clearance vertically and laterally, and the canyons open up. The localizer back course is well placed to provide the most accurate course guidance where it's most needed, and there is no "mockery" of anything. It's actually a well-reasoned approach, particularly given the terrain. If you've never flown there, you might not fully understand why. What you would understand, however, is what's required of you as a pilot, because it's clearly shown on the approach charts and departure procedures.

[galaxy flyer]

Aterpster

Perhaps, Jeppesen was better at challenging the FAA TERPS office when their V-P in charge was named Terpstra. Jim is wonder of knowledge on the subject and, in my two meetings, a gentleman.

GF

[SNS3Guppy]

Oh, sure. Let the cat out of the bag, why dontcha!

[aterpster]

galaxy flyer:

Perhaps, Jeppesen was better at challenging the FAA TERPS office when their V-P in charge was named Terpstra. Jim is wonder of knowledge on the subject and, in my two meetings, a gentleman.

Knew Jim well and worked with him a lot. His successor is a sharp guy, too.

This has more to do with staffing levels and insights of past workerbees vs. present.

It is somewhat like the FAA staffs who design these procedures. They used to be pilots and used to be more accountable to the various FAA regions.

[SR71]

aterpster,

My comment was merely drawing an analogy between the fact that, if one accepts that you want your precision guidance close to the nastiest terrain, then one presumably also accepts one wants it closest to the runway. But tracking away from the DBL towards the runway obviously isn't giving you that.

Then I thought about it, and, I guess there isn't much point sticking a VOR at the bottom of a valley, and bearing in mind you locals who know the terrain say there is room for manoeuvre in the vicinity of the MAP, the benefits of locating the beacon out there outweigh the contravention of the general principle in the aforementioned paragraph.

In addition Guppy makes the good point about the benefit on the VOR approach:

Whereas the VOR approach begins at the highest terrain, it provides the most accurate guidance closest to that terrain

However, Guppy also says:

I don't presume to know why Jeppesen may include a warning on their chart...

then says

NACO publishes the Aspen charts (as does Jeppesen) with a notation on the localizer course because it serves to clarify...

so really, unless he is playing on the distinction between NACO and Jepp, he knows what the note is there for like I said.

But, purely in the interests of curiousity:

1) Why is that note not on the FAA VOR plate? Is it on the Jepp VOR plate?
2) Why does the FAA plate suggest dual nav receivers are needed for the VOR and not the LOC? What do the Jepp plate(s) say?

[aterpster]

SR71:

But, purely in the interests of curiousity:

1) Why is that note not on the FAA VOR plate? Is it on the Jepp VOR plate?
2) Why does the FAA plate suggest dual nav receivers are needed for the VOR and not the LOC? What do the Jepp plate(s) say?

Jepp and FAA charts are identical as to the notes, or lack thereof. The FAA has been informed of the discrepencies today. Stay tuned.

[galaxy flyer]

You think this confusing, the GLEX nav database approaches for KASE do NOT match any of the plates. VMC at Red Table or join the crowd at Rifle or Eagle.

GF

[Zeffy]

GF

You think this confusing, the GLEX nav database approaches for KASE do NOT match any of the plates. VMC at Red Table or join the crowd at Rifle or Eagle.

That's because the NZ-2000 FMS doesn't do any circling-only approaches. So it's not just at Aspen.

The Aspen approaches in your database are Special Approaches.

Check this recent "Direct-to" Newsletter.

Question: Some approach procedures do not match the paper charts. Why?

Answer: Our The NZ-2000 database contains some special instrument procedures which require written authorization from your Principal Operations Inspector or Flight Standards District Office prior to use. Special charts are required in all cases and additional aircrew training and specific aircraft performance may be required. A current list of special approached can be obtained from honeywellaes.com. As well as the special procedures that are included in the navigation database, FMS software versions NZ6.0 and Primus Epic 7.0 and prior do not support circling approaches. If your FMS software version does not support circling approaches, they will not be available for selection into the flight plan.

The Aspen Specials are a boon to operators willing to obtain the requisite approvals from FAA Flight Standards.

There's a straight-in version of the LOC/DME-E (Approach title is LOC/DME Rwy 15) and an RNAV (GPS) Rwy 15.

[galaxy flyer]

Thanks, Zeffy, one learns something everyday, if one pays attention.

GF

[tommy1-8706]

Flt Sim 2004 instals IPKN as a Localiser with course 120 degrees.
Hence, heading 300 in a Cessna, say, the needle is not normal sensing.

[PBL]

terpster and SR71 have raised the issue of nav data base integrity (paper or electronic, issues are similar). It's a lot more complicated than just a couple of places where things can go wrong.

I don't recall either terpster or SR71 being on the bluecoat list. The Bluecoat 2001 annual meeting was held at LHR just a month after 9/11. It wasn't super-well attended because of that, but there were some very informative talks indeed. One was from Lee Carlsen, of Smiths, in Grand Rapids, Michigan, who talked about the issues of nav data base integrity. I wrote up a conference report. Here are my notes on Lee's talk. I apologise for the length.

I am also concerned about thread creep. Over the time I've been on PPRuNe I think I have tried to start three threads. Each one has silently disappeared within minutes of my starting it. However, my contributions to existing threads don't disappear. JohnT moderates transparently and I'm sure he will make the necessary structural changes if this is too much creep.

[begin Bluecoat 2001 notes on Lee Carlsen's talk]

Lee Carlsen told us about Nav database integrity, lavishly illustrated with some unnerving photos from Unusual Aviation Pictures . He succeeded in persuading me, at least, of the significance of this problem of heterogeneous engineering. The chain is as follows.
1. Survey;
2. Compilation of survey data by the state or official agencies;
3. Data given to DB providers (Jeppesen, Thales, etc) for processing;
4. Data processed by DB providers;
5. Formatted data given to Navionics providers for formatting and compactification for their products;
6. Product-adapted data returned to DB provider for distribution to customers;
7. Distribution to customers;
8. Installation in airplane;
(9. Pilot's fingers......).
During any of these processes, data could become corrupted. Surveyors make mistakes (or, in some cases, require and provide half their data as WGS-84 and another half using traditional measures, as in Mexico), and at any other point in processes 2 through 6 finger trouble at data entry or lack of correctness of programs processing the data can cause corruption. Customers may not necessarily install new data correctly. And all that before it gets to the pilot. Lee gave us a quick survey of the methods that can be reasonably applied to assure high integrity: tools can be provided to the DB producers to check output against input for steps 4 and 5, and to check output to step 6 against output to step 4 (and thus against input to step 4 for those with a tool for this also). Output can be assured wrt input for steps 3 and 7 by including error detection (or even error-correcting encoding) on the distribution medium. Such methods could also be used to prevent successful installation if there is any data corruption on the medium.

However, while all this is technically trivial, it is a significantly large if not gargantuan task of heterogeneous engineering involving many actors, some of whom (such as the states) are not necessarily motivated by any externalities such as a threat of getting sued over mistakes.

In my own work I encounter data integrity problems, and their significance for safety-related systems cannot be underestimated. But the problem of assuring integrity seems to be much more difficult than I had heretofore thought it.

[end Bluecoat 2001 notes]

PBL

[stubby1]

dear hiren

The funda is that your instrument senses the two lobes and assumes that you are flying the set course in ILS.
so in this case you put the course to the final & arm the back course.
the confusion is over the term "back course' which actually means something else (behind the localiser). however the use of this reverses the lobes & you get correct guidance on the outbound. Backcourse can be simply read as reversing the sense. you can also use it in flying the actual back course ( not in India).
.

read this slowly to digest. you can also check with do-228 pilots for clarification.

here you are flying outbound of front course.