Sunday, July 10, 2011

Chart Notes

I’ve decided to start writing some notes on instrument procedures and approach plates. I was going to title it “Chart Clinic”, but that title has been used in other publications, so I settled on the title of “Chart Notes.” I will make my disclaimer right now. I don’t claim to have any special knowledge or expertise. So feel free to let me know when I have taken a turn into the weeds. The information from this first note comes from the 2011 FAR/AIM, specifically section 5-4-5 of the AIM. I have tried to pick out approaches to illustrate the AIM and in some cases found myself confused by the wording in the AIM and a charted procedure. In all of these discussions, you are invited to submit procedures that you have questions about. Maybe together we can figure them out.

Most of us have had the experience of looking at an approach plate and wondering “What does that mean?” and more importantly, does it affect me and if so, how. So welcome to the first installment of Chart Notes. Today’s note covers the topic of equipment, and how it applies to an approach plate.

The equipment required to join and fly an instrument approach procedure (IAP) is listed in the title and in the notes. Straight-in IAPs are identified by the navigation system providing final approach guidance and the runway to which the approach is aligned, for example VOR RWY 13. Circling only approaches are identified by the navigation system providing final approach guidance and a letter, for example VOR-A. More than one type of navigation system separated by the word “or” means either type of equipment may be used, for example NDB OR GPS RWY 34. More than one type of navigation system separated by a slash indicates more than one type of navigation equipment must be used to execute the final approach segment. Take for example VOR/DME RWY 27 at Anoka (ANE).


Notice the word DME appears in two different places on the procedure, once in the title and a second time in the notes. Let’s take DME in the title first. Whenever an approach requires more than one type of equipment to execute the final approach, the types of equipment will be listed in the title of the procedure, separated by a slash. Hence both DME and VOR equipment is required to execute the final approach segment of this procedure. But DME also shows up in the Notes section of the chart. What does this mean? Whenever radar or other equipment is required on portions of the procedure outside of the final approach segment, including the missed approach, a note will be charted in the notes box of the pilot briefing portion of the approach plate. So DME REQUIRED in the notes box indicates DME is required to fly the initial and intermediate segments of this approach. DME in the title indicates DME is required to fly the final approach segment of the approach. Notes are not charted when VOR is required outside the final approach segment.

Now let’s look at another approach. For this example I have used the ILS-31 at Saint Cloud (STC). This is one of those procedures that I find at odds with the AIM.

In this case, ADF REQUIRED appears on the planview of the procedure. When radar or other equipment is required for procedure entry from the enroute environment, it will be charted on the planview of the approach. There is no way to get to the IAF HUSSK from the enroute environment without having an ADF. V2 passes to the south of the STC VOR and V413 passes to the north of it. I could make the argument that you could get to it from via the transition route from Gopher (GEP) VOR, which is listed as being an IAF, but I’m not a Terpster. I’m simply illustrating what the AIM says. Or maybe the approach plate notation is wrong. My instructor and I have had numerous discussions over this approach. He says, quite logically, that ADF is required for the MAP. I agree, but to be strictly in accordance with the AIM, then it should also be listed in the Notes section of the pilot briefing strip. One possible explanation is that the ADF notation on the planview serves both requirements. I’m not completely convinced, but for lack of any other explanation, I’ll accept it.

According to the 2011 AIM, the FAA is in the process of changing the notation for LOC approaches that are charted on an ILS approach when the LOC approach requires additional equipment. The AIM states the LOC minimums will be annotated with the navaid required. I’ve looked at a number of ILS/LOC approaches, and they all show the required equipment as shown below in the ILS or LOC/DME for RWY 27 at Anoka.

The word DME appears in the title, the planview, and in the profile view. Granted in the profile view it is shown as DME distances off the localizer. LOC/DME in the title indicates DME is required to execute the final approach segment when flying the procedure as localizer only. The DME notation in the planview indicates DME is required to get from the enroute environment to procedure entry. In this case, both IAFs are DME waypoints. In the profile view, the FAF, the step-down waypoint KOGGE and the MAP point are all DME waypoints.

In all of these procedures, an IFR GPS may be used to substitute for ADF or DME equipment. The GPS is a legal substitute for DME. You can make the navaid the active waypoint, such as GEP for the IAFs. You can also utilize the database when it contains the DME waypoint, such as BLAYN or BOKYA. But here’s a “gotcha” moment if you are using GPS to provide this information. When the GPS-27 procedure for Anoka is loaded in the GPS, examination of the waypoints inserted into FPL0 will show that KOGGE is missing. When I called Jeppeson about this, their response was that they do not insert step-down fixes for a LOC approach when that approach is charted with an ILS procedure. So how do you find KOGGE if you are localizer only? The GPS will not allow you to insert KOGGE into FPL0 between BOKYA and the MAP point. One way of doing it is to make IANE, the localizer ID, the active waypoint. Earlier Garmin units would indicate it is an intersection, but it gives you the correction information. I have loaded this approach in a Garmin 430(W), a Garmin G1000, and a KLN94. None of them insert KOGGE into FPL0. This trick works most of the time. However once in a while it does not know what the localizer ID is. Your only choice then might be to stick KOGGE at the end of FPL0 or you might be able to find it from the nearest intersection page.

Another symbol that has started to appear on the briefing strip is a “W” on a black field. The AIM says this means that outages of the WAAS vertical guidance may occur daily at this location due to initial system limitations. For flight planning purposes, the LNAV minimums should be used. In flight operations it says vertical guidance may be used to complete the approach if LPV or LNAV/VNAV minimums are available. An illustration of this is GPS-RWY 21 at Madison (MSN). Below I have reproduced just the briefing strip and the minimums portions of the procedure.

The “W” indicates WAAS vertical guidance may not be available, as stated above, but now look at the minimums for the procedure; the WAAS minimums are NA. So you have to go with the LNAV minimums. Also, on the briefing strip, the ASR means “published radar minimums at this airport.” One final note on the nomenclature used in the minimums section, “GLS PA DA” stands for “G(PS) Landing System. The GLS NA restriction will be removed when the LPV minima is published.

One final comment is needed here to clarify the LNAV/VNAV DA on the minimums section of the procedure. This appears on many GPS procedures, and as you probably concluded, it stands for “Lateral navigation/Vertical navigation. In order to utilize these minima, an aircraft must be equipped with:

· WAAS avionics approved for LNAV/VNAV approach or

· A certified Baro-VNAV system with an IFR approach approved GPS or

· A certified Baro-VNAV system with an IFR approach approved AWAAS or

· An approach certified RNP-0.3 system with barometric vertical guidance (Baro-VNAV)

Baro-VNAV refers to certain RNAV systems that present vertical guidance to the pilot based on a specific vertical path which is predicated on barometric pressure. My guess is that these systems generally predated GPS. Bottom line – mostly that doesn’t apply to the majority of us.

I’ll conclude this discussion with the two ILS approaches into Billings (BIL), starting with ILS-10L.



ILS-10L has an IAF at the LOM, SAIGE. There is a transition shown from the BIL VOR to the LOM. The transition is a heading of 298°, a distance of 3.9 nm and is flown at 6000’. This takes you from the enroute environment to the procedure, so no additional equipment is needed. But now look at ILS-28R.



In big letters on the planview, are the words RADAR REQUIRED. If you study the approach, you will see there is no way to get from the enroute environment, the BIL VOR, to the procedure. There is no transition to the localizer. Consequently the words RADAR REQUIRED mean that you must be vectored to the approach by ATC. Although SUTLE is designated as an IAF, a procedure turn is not authorized. Also the title indicates DME is required for the localizer-only approach, as is also shown in the profile view.

I believe I have rambled on long enough, so will end it here. Your comments are welcomed.





7 comments:

aking said...

Even though i'm close to PPL and not really have a full idea how the approach chart works on, but i have to say Thank You for share your thoughts here...

really appreciate it

small private airplane injuries said...

Thank you for sharing this.

Sarah said...

Good to see you're writing again!

I have a question which is dumb enough I should probably ask anonymously...

You explain that navaids required to fly the final approach course are in the title, e.g. "LOC/DME RWY 27". Navaids required for other reasons on the published approach - like for missed approach navigation or the initial/intermediate segments - are in the "notes" section, e.g. "ADF required". If a navaid is required to get from the enroute to the final approach course - it will be on the plan view. Am I understanding you correctly so far?

So my dumb question is, for the "ILS or LOC/DME RWY 27" approach to KANE, does the plan view notation "DME REQUIRED" mean you must have DME to fly the ILS "for real" under IFR? I don't think that's the case... so why doesn't it say "DME or RADAR required"?

Thanks!

Linda said...

Okay, here's my best guess. The note DME REQUIRED in the plan view is there so that the pilot can get from the enroute environment to one of the two IAFs. Both of those IAFs require either DME or IFR GPS.

But if I understand your question correctly, you are asking if DME is required to fly the ILS-27 if you are in radar contact and are being vectored for the approach. My best guess is no. However, trying to guess what the FAA actually had in mind can be a hazardous undertaking.

When researching the AIM for this article, I came to the conclusion that some of these equipment notes, such as the ones on the plan view, are based on a lost comm scenario.

As I said, that's my best guess.

Linda

Linda said...

In researching the AIM for this article, I came to the conclusion that equipment notes like those in the plan view are there for the purpose of getting the pilot from the enroute environment to an IAF. Think lost comm. So if you had lost comm and were trying to get into Anoka using the ILS-27, then yes, DME or GPS would be necessary.

But your question, if I understand you correctly, is that if you are in radar contact with ATC and are being vectored for the ILS-27, is DME (or IFR GPS) still required? My best guess is no. But trying to second-guess what the FAA had in mind is always a hazardous undertaking.

Linda

Anonymous said...

My answer is, "yes, DME is required, but only if you are flying a localizer approach." DME is the only way that the FAF can be identified and descent to the MDA commenced. You will be vectored to the approach course but you still need to ID the FAF, which is 6.9 NM from I-BMO. If you are using the ILS then the glide slope intercept at 5,200 ft will allow you to descend to the DH, thus DME is not required for an ILS approach.

Anonymous said...

This is an excellent discussion. Just a comment about the ILS or LOC 31. You said that you thought that ADF is required for the MAP. It's not.

There is technically no "MAP" for an ILS - the "MAP" DA on glideslope. On the LOC-only approach, the MAP is technically identified through timing.