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ILS Z Runway 27 Helena

PostPosted: Fri Dec 18, 2020 6:45 pm
by gregloegering
I was flying from Boundary County Airport to Helena to get positioned for the Sky High Charter scenario 7, and did not read the ILS Z procedure correctly. I was cleared direct to the Helena VOR at or above 10,000 and then cleared to fly the ILS approach. I assumed that the procedure required that I fly to the IAF CUSDA and fly a DME arc around until established on the localizer.

But apparently I was supposed to fly a heading of 090 and use a procedure turn to get established on the localizer. The controller tried to kindly explain what I had done wrong, but I was too busy flying to really understand what she was telling me. Are there any videos or web pages that explain this chart? I'd sure like to understand what she was trying to tell me. Thanks.

Re: ILS Z Runway 27 Helena

PostPosted: Fri Dec 18, 2020 8:02 pm
by Kevin_atc
Hi Greg,

This is a neat approach. Before we dive into how it’s supposed to be flown, I think there will be value in breaking down your thought process in a constructive way. Is there a reason you chose to fly from HLN direct to CUSDA to join the approach rather than HLN direct to HUDVU, or even NNORA or PATRR to join the approach?

Re: ILS Z Runway 27 Helena

PostPosted: Sat Dec 19, 2020 9:56 am
by gregloegering
Hi Kevin,

Thanks for tackling my question on the Helena ILS approach. I was predisposed to fly to CUSDA because it was marked on the procedure as the 'IAF'. I assumed that this was similar to the LOC/DME RWY 3 approach to Durango that was flown for the Sky High Scenario 2.

One of the things that the controller pointed out to me on the Helena approach after I was on the DME are, was that the route from the HLN VORTAC to CUSDA on the R-336 radial is marked as a thin line. And then I realized that this means that it is not part of the flyable procedure, but rather a notation that CUSDA is on the R-336 radial of the HLN VORTAC.

What isn't clear from what I heard from the controller nor my looking at the procedure later is what is it on the procedure that tells the pilot to fly heading 090 at 9700 feet to the HAU NDB. I see the note with an asterisk, but don't see anything else on the chart that says to fly it this way.


Re: ILS Z Runway 27 Helena

PostPosted: Sat Dec 19, 2020 10:29 am
by Keith Smith
Definitely take some time to watch the free workshops on instrument approaches (

Briefly, the leg that you assumed to exist from HLN to CUSDA is not flyable because it doesn't show a distance and minimum altitude for the leg. Also, the thickness of the line implies that it's for identification of CUSDA and nothing else.

Also, identical lines exist from HLN to *5* other IAFs. So, it would be tough to argue that CUSDA is the right call when there are 5 other seemingly-viable candidates. That should've raised a red flag that perhaps something was amiss, because IFR approaches normally do not contain that level of ambiguity.

Take some time to learn about full approaches, the workshops should be able to get you there. This was also covered in quite a bit of detail in the I-6 rating, that would be worth revisiting. (Note, the graphics appear to be no longer loading on the I-6 page, I will fix that, but you can pull up the ILS chart and follow along).

Once you're comfortable with this approach, I'd suggest pulling up 20 or so approach plates back to back and trace your finger over the lateral flight path that you would fly if you were cleared from any feeders or IAFs on the plate. Once you've done it 20 times, you rarely learn anything on the 21st time. Use a wide variety of samples and you'll rarely be surprised in the future.

Re: ILS Z Runway 27 Helena

PostPosted: Sat Dec 19, 2020 10:37 am
by Keith Smith
Note: fixed the 2 graphics on the I-6 rating, will check the other ratings for similar issues. It appears to be a chrome policy regarding embedding images using non-secure image URLs (the images are hosted on a legacy platform)

Re: ILS Z Runway 27 Helena

PostPosted: Sun Dec 20, 2020 4:58 pm
by gregloegering

I've actually watched your IFR workshops, and definitely learned a lot about them. So thanks for the information and your great ATC service.

I'm still wondering what it is about the Helena ILS approach that got me flying it incorrectly. I even went back to listen to the ATC recording of the flight to see what I could learn there.

From what I've been able to determine, is that I needed to look for text that has an altitude and a DME distance. This is exactly what the text in the procedure was that had an asterisk and said "*9700 to NDB 090 degrees/8.4 miles". And this is exactly what the controller told me when she was explaining my mistake.

I am now sensitized to this and will make sure to look closer at the procedures for this type of information.