Identifying the MAP on ILS when going missed before it

Mattio

Mattio

Well-Known Member
Ok, so the missed approach point on an ILS is DA on the glide slope. However, if you go missed before the MAP, how are you going to identify the MAP if you don't have DME? I've looked through the Instrument Procedures Handbook to no avail.... Look at this chart for example:

http://204.108.4.16/d-tpp/1006/05295ILD6.PDF

DME is not required and there is no time published (granted it would apply to the non-precision approach anyways). I'm wondering what is the legal way of identifying the missed approach point to start your turn if you go missed early and start your climb? Just wing it? Calculate your own time? Anyone?

I found this article too, that explain why the author doesn't agree with timing in most cases:

http://www.terps.com/ifrr/aug98.pdf
 
Middle marker (assuming it's pretty close, which it usually is on a Cat I), GPS, DME, or, if none of the above is available, time. I don't have regulatory verbiage to back that up, but that is what I would go for.
 
Wally Roberts' article was more aimed at presenting a hypothesis that switching from an ILS to a LOC approach during the approach was not the best idea. As far as determining the MAP other than at the DA, that would still be a matter of timing, verified by any other available resources such as DME, MM, and Radar.
 
I believe the MM approximates decision height on the glide slope but isn't always exactly co-located. At least, that's what I remember. I was just wondering if there was a technical, legal way of identifying it.
 
Even if no time is published, you should still have an idea how long it will take you to get from the FAF to the MAP.

I think of it like this.

"Okay our Vref is 104, so we're going to be coming down final roughly 104-111. Winds are quartering off the left at 7 so let's call it a 5 knot headwind...so about 100 across the ground give or take. So since it's 5 miles from the Marker to DH, at a mile and a half (roughly) per minute, that's about 3.5 minutes."

Close enough for me. Get climbing to MSA and DR to the MAP, then DR the Missed approach instructions.

-Roadhouse
 
DME is required look at the name ILS or LOC/DME RWY 6. If your looking through the insturument procedures handbook go to page 5-8.
 
s60 said:
DME is required look at the name ILS or LOC/DME RWY 6. If your looking through the insturument procedures handbook go to page 5-8.
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If DME were required for the ILS, wouldn't it be ILS/DME or LOC/DME RWY 6?

....I don't pay attention enough to notice if there's a difference (and I haven't taught basic instrument in a while), but that seems logical to me.

-mini
 
Mattio said:
I believe the MM approximates decision height on the glide slope but isn't always exactly co-located. At least, that's what I remember. I was just wondering if there was a technical, legal way of identifying it.
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That is correct. Because of anomalies in the ground, it may not be possible or practical to position the MM at the exact spot.
 
minitour said:
If DME were required for the ILS, wouldn't it be ILS/DME or LOC/DME RWY 6?

....I don't pay attention enough to notice if there's a difference (and I haven't taught basic instrument in a while), but that seems logical to me.

-mini
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I may be mistaken, as I haven't taught instruments in a while either (and reading the regulatory mumbo-jumbo can be confusing), but I believe that AIM paragraph 5-4-5(A)(3)(c) is saying the DME will only be tacked on to the LOC portion, but it is required for both. It states, "The FAA has initiated a program to provide a new notation for LOC approaches when charted on an ILS approach requiring other navigational aids to fly the final approach course. The LOC minimums will be annotated with the navaid required (e.g., "DME Required" or "RADAR required"). During the transition period, ILS approaches will still exist without the annotation." It's rather wordy, but that's what I think it means. Also, there is an approach at Durango, CO (DRO) from 10/24/2003 that was the ILS/DME Rwy 2 that now reads ILS or LOC/DME Rwy 3. I know that it's possible the approach is not the same as it was 7 years ago, but it's the best I could find. The only approaches that came up when I googled "ILS/DME or LOC/DME" were in Canada and other foriegn countries. That's the best I could find.
 
minitour said:
If DME were required for the ILS, wouldn't it be ILS/DME or LOC/DME RWY 6?

....I don't pay attention enough to notice if there's a difference (and I haven't taught basic instrument in a while), but that seems logical to me.

-mini
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Not always. Sometimes they'll stick a "DME REQUIRED" on the planview, or even in the notes, but the title of the approach will show no evidence of it. I have no idea why they do it that way.
 
Xiph said:
Not always. Sometimes they'll stick a "DME REQUIRED" on the planview, or even in the notes, but the title of the approach will show no evidence of it. I have no idea why they do it that way.
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Yeah, I'm familiar with that. I was just trying to remember how the approaches are labeled and if the label for DME applies to both the ILS approach and the LOC approach.

Kind of off topic, but I'm going to anyway.

Anyone noticed how Canaduh has "ILS, LOC, or NDB RWY 06" on some of their plates?

Is there a good reason we don't do that here when the NDB approach is just an approach using the LOM and the same final approach course? I'd love to be able to drop a binder or two and I think if we could overlay more procedures onto less paper I could probably get away with it.

-mini
 
minitour said:
If DME were required for the ILS, wouldn't it be ILS/DME or LOC/DME RWY 6?

....I don't pay attention enough to notice if there's a difference (and I haven't taught basic instrument in a while), but that seems logical to me.

-mini
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That is how I understand it.
 
subpilot said:
That is how I understand it.
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You understand it that if the title reads "ILS or LOC/DME RWY12" then if you are not using the S-ILS minimums (or I guess side-stepping if it's there), you have to have DME, but if you're on the ILS (using the GS), DME is not required?

-mini
 
I hope I'm not giving out any secrets here, but everyone knows the LOC transmitter is just off the far end of the runway, and it acts just like a vor when you cross it. The LOC needle swings wildly back and forth as you cross over, and becomes very difficult to hold centered as you approach the transmitter. With a little practice, you can tell when you are about to run out of runway to start a climb, or start a turn.
 
minitour said:
If DME were required for the ILS, wouldn't it be ILS/DME or LOC/DME RWY 6?

....I don't pay attention enough to notice if there's a difference (and I haven't taught basic instrument in a while), but that seems logical to me.

-mini
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mini,
This is from the current TERP's manual. Notice what it says about ILS and DME. I know there are some approaches out there that are labeled ILS/DME, but don't know if that is an error or perhaps it was permitted to label that way in the past. Just wanted to pass it on for whatever it is worth.
 

Attachments

minitour said:
You understand it that if the title reads "ILS or LOC/DME RWY12" then if you are not using the S-ILS minimums (or I guess side-stepping if it's there), you have to have DME, but if you're on the ILS (using the GS), DME is not required?

-mini
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yes.
 
ghogue said:
mini,
This is from the current TERP's manual. Notice what it says about ILS and DME. I know there are some approaches out there that are labeled ILS/DME, but don't know if that is an error or perhaps it was permitted to label that way in the past. Just wanted to pass it on for whatever it is worth.
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According to that reference, DME is never required to fly an ILS. Makes sense to me.
 
subpilot said:
yes.
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Same. Just wanted to make sure I read you right.

subpilot said:
According to that reference, DME is never required to fly an ILS. Makes sense to me.
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Not sure about that, though. I've flown several approaches (not necessarily recently) where DME was required as well as RADAR. Mostly due to no "feeder" to get from the enroute structure down to the approach phase and no marker beacons or cross-radials.

I wouldn't say DME is never required on an ILS, but I admit...........I didn't read the TERPS thing yet.

Still writing my story.

-mini
 
minitour said:
Same. Just wanted to make sure I read you right.


Not sure about that, though. I've flown several approaches (not necessarily recently) where DME was required as well as RADAR. Mostly due to no "feeder" to get from the enroute structure down to the approach phase and no marker beacons or cross-radials.

I wouldn't say DME is never required on an ILS, but I admit...........I didn't read the TERPS thing yet.

Still writing my story.

-mini
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mini,
The question was about how an ILS would be titled and the reference from TERPs was referring to DME in the title of an ILS approach. Equipment listed in the title refers refers to equipment requirements for flying the final segment. When you see radar, DME or ADF listed elsewhere on the chart, it is referring to other than the final segment. e.g., if DME is listed in the plan view, it means it's required for getting from the enroute portion of the flight and onto the approach. If shown in the notes section, then it is required for some portion of the approach other than the final segment.

Take a look at AIM 5-4-5 a. 3. (a) and (b)

When subpilot said "according to that reference, DME is never required to fly an ILS", that was for the final segment, not that it wouldn't be required for other parts of the approach.

gary
 
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