ILS/LOC approach MAP confusion

[Audipilot1]

I'm taking my IFR check ride on Saturday and I'm just at a loss for determining what the MAP is for the localizer approach to runway 4 at ksby. If you look at the attached approach plate you'll see timing and a distance of 5.9 from FAF to MAP. However, if you look at the profile view there is an asterisk at 1.9 DME which is only 4.9 from the FAF. SO is the MAP 4.9 or 5.9 from the FAF?

Thanks very much for your response.... This is driving me crazy.

[carqwik]

One is for the LOC only approach, the other is for the ILS.  Note the asterisk...

[Marauder]

I think you meant the Localizer approach to 32. I don't see a Localizer approach for 4. The localizer approach MAP is timed and the ILS would be down to the DH. Sent from my iPad using Tapatalk

[Audipilot1]

Yes, I meant for 32. Mixed that up. Ere isn't timing or dme on the ils so why does that say 5.9 when the profile view asterisked at 4.9?

[Marauder]

Now for a trick question. Can you fly this approach without a DME?

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[Audipilot1]

One is for the LOC only approach, the other is for the ILS.  Note the asterisk...

Yes , I see this, however take a look at the timing chart where it notes 5.9 between FAF and MAP. That's my confusion because I see the asterisk you reference and that is only 4.9 FAF to MAP.

[Audipilot1]

Now for a trick question. Can you fly this approach without a DME?Sent from my iPad using Tapatalk

Yes with timing.

[PMcClure]

Technically for an ILS, isn't the MAP decision altitude on slope, not a distance? I believe the time is only for the LOC and a back up only when flying the ILS in case you lose the glideslope input and decide to continue on LOC (lateral) guidance only. I think Marauder is saying the same thing. 

 

The answer to the examiner should be DA on slope - technically not a distance when flying and ILS. At least that is my understanding. 

Edited June 13, 2014 by PMcClure

[47U]

The MAP is 5.9 nm from the FAF (0.8 DME) for the LOC and circling minimums.

The asterisk denotes the bold V at 1.8 DME for the visual descent point applicable to the LOC approach only. If you are flying a circling approach, you will be 60' higher on the MDA (480' vs 420') than the LOC approach so the visual descent point does not apply.

Right?

Aren't instruments fun?

[Audipilot1]

The MAP is 5.9 nm from the FAF (0.8 DME) for the LOC and circling minimums.

The asterisk denotes the bold V at 1.8 DME for the visual descent point applicable to the LOC approach only. If you are flying a circling approach, you will be 60' higher on the MDA (480' vs 420') than the LOC approach so the visual descent point does not apply.

Right?

Aren't instruments fun?

AHA.... I think I get it now. MAP "is" 5.9 for localizer, however, the VDP (which is what is asterisked) is at 4.9. THANK YOU.

[Marauder]

This approach is a little weird. And I can see your confusion -- because it got me thinking as well... The 5.9 is the distance from the FAF to the MAP for the full ILS approach. If you lost your glideslope on the approach, you would be restricted to the LOC altitude. I would normally have said that you flew that altitude until the time is expired and then commenced the missed. But with the LOC DME marker at 1.8 miles on the profile, it almost looks like the expectation is that you go missed further out and ignore the timing. Is that your confusion as well?

Now I'm curious what others think...

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[Marauder]

The MAP is 5.9 nm from the FAF (0.8 DME) for the LOC and circling minimums.

The asterisk denotes the bold V at 1.8 DME for the visual descent point applicable to the LOC approach only. If you are flying a circling approach, you will be 60' higher on the MDA (480' vs 420') than the LOC approach so the visual descent point does not apply.

Right?

Aren't instruments fun?

I missed the VDP! That clears it up...

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[M016576]

Yes , I see this, however take a look at the timing chart where it notes 5.9 between FAF and MAP. That's my confusion because I see the asterisk you reference and that is only 4.9 FAF to MAP.

With the non-precision approach, the timing takes you all the way to the runway environment, but makes no guarantees for glideslope. That VDP will net you a 3 degree G/S. Remember, the DH doesn't apply to you on a localizer... You're going down to your MDA and either flying to the MAP (with dme) or until you get the runway environment in sight (or timing expires- no dme). While it's wise to use the VDP to keep you safe on those approaches, it's not required.

That's a low MDA for us mountain folk- I'm used to seeing 600-1000' mda's on non-precision approaches out here! I guess the trade off is that you may have low mda's out there on the east coast... But with that weather, you need them!

[Audipilot1]

I missed the VDP! That clears it up...

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Yup exactly! Now that I have about 50 hours instrument in a Piper Arrow (with a garmin 430) it will be a big learning curve jumping to my 231 which has a GNS 480 once I pass my check ride.

[carqwik]

Ok...yes, I stand corrected...the 4.9 DME fix is at the VDP, not the MAP.  Damn...I should have thought that through a bit more having never seen two different MAPs on one chart....duh!!

[jlunseth]

Sorry but no. 1.8 is not the MAP for the LOC. It is the VDP. That is what the "V" symbol means. A missed approach should be considered if, at the VDP, you do not have sufficient references to make a normal descent to a landing. Normal descent is 3 degrees. However, the MAP is still 0.8 . The VDP is more important to large aircraft that could overrun if a normal descent is not maintained. an Examiner would surely not fail you if you went missed at the VDP, but you should get your terminology straight. The MAP and the VDP are not the same. There is only one MAP on that plate.

[Audipilot1]

With the non-precision approach, the timing takes you all the way to the runway (not just to the dme MAP). Remember, the DH doesn't apply to you on a localizer... You're going down to your MDA and either flying to the MAP (with dme) or until you get the runway environment in sight (or timing expires- no dme). While it's wise to use the VDP to keep you safe on those approaches, it's not required.

That's a low MDA for us mountain folk- I'm used to seeing 600-1000' mda's on non-precision approaches out here! I guess the trade off is that you may have low mda's out there on the east coast... But with that weather, you need them!

It's quite fun breaking out that low and the runway is right there. Unfortunately for me, breaking out has meant taking my foggles off. Haha.

[Marauder]

Technically for an ILS, isn't the MAP decision altitude on slope, not a distance? I believe the time is only for the LOC and a back up only when flying the ILS in case you lose the glideslope input and decide to continue on LOC (lateral) guidance only. I think Marauder is saying the same thing.

The answer to the examiner should be DA on slope - technically not a distance when flying and ILS. At least that is my understanding.

That is correct. I don't think I ever flew a precision approach based on timing. But have done a lot of timing on precision approaches anticipating they would become non-precision.

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[Audipilot1]

Thanks everyone for their input. This has been a nice introduction to the forum and a great help in clearing up my confusion.

[Marauder]

BTW -- Audipilot1, thanks for the refresher. This is much more exciting than talking about LOP, CamGuard and whether I take-off with flaps or not

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[Marauder]

And... Good luck on the check ride!

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[Marauder]

With the non-precision approach, the timing takes you all the way to the runway environment, but makes no guarantees for glideslope. That VDP will net you a 3 degree G/S. Remember, the DH doesn't apply to you on a localizer... You're going down to your MDA and either flying to the MAP (with dme) or until you get the runway environment in sight (or timing expires- no dme). While it's wise to use the VDP to keep you safe on those approaches, it's not required.

That's a low MDA for us mountain folk- I'm used to seeing 600-1000' mda's on non-precision approaches out here! I guess the trade off is that you may have low mda's out there on the east coast... But with that weather, you need them!

We're pretty fortunate not to have the big mountains to contend. We also get the benefit of some big negative density altitudes in the winter.

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[MB65E]

BTW -- Audipilot1, thanks for the refresher. This is much more exciting than talking about LOP, CamGuard and whether I take-off with flaps or not

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Absolutely!!

Good luck!!

-Matt

[PTK]

Audipilot1, as you know, depending on the non-precision approach the MAP horizontal location can vary. The VDP is there to help you decide if you need to initiate the missed before reaching the MAP. It's located before the MAP, as you noticed, and at the MDA. A comfortable landing (i.e. by continuing the typical 3° descent angle) can still be made from the VDP assuming runway environment is visible. But probably not after it as the angle would steepen because you must fly level at MDA. As depicted in the profile view.

If the runway environment is not there at the VDP on a non-precision approach it's urging you to go missed.

Good luck on your check ride!

[John Pleisse]

Hey Buddy!!! Good luck with your checkride. Which examiner did you choose? Would love feedback about your ride after passing the first time with flying colors.