ILS DME Approach into Mazatlan

HPNPilot1200

HPNPilot1200

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Jason
Hypothetically, you are proceeding direct MZT at 4,000 and are cleared for the ILS DME 1 Rwy 26 at Mazatlan. What altitude would you descend to upon crossing the VOR? 3000? 2500? The 3,000 ft altitude placed in the profile view is sort of confusing on this approach. If you look at the VOR DME 1 approach, the profile view is much clearer.

I'll provide my opinion as the discussion develops...

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Some of us can't read those cartoon charts!
 
3000 outbound on the 103R until 9 DME, descend to 2500 during the turn
2500 until crossing 9 DME inbound on the inbound radial

I'll agree the VOR approach is much clearer.
 
I'm saying 3,000 until the first 9 DME and 2,500 until the second 9 DME.
 
To me it looks like 3000ft when crossing the VOR outbound, then passing DME 9.0 you descend to 2500ft and start the inbound turn. Once established inbound on the localizer and having passed DME 9.0 inbound, you can mosey on down to 1600ft until intercepting the glideslope at DME 6.0 on the VOR or 5.1 on the localizer-associated DME.

But I'm not too familiar with Jepp charts. Am I missing something?
 
pericynthion said:
To me it looks like 3000ft when crossing the VOR outbound, then passing DME 9.0 you descend to 2500ft and start the inbound turn. Once established inbound on the localizer and having passed DME 9.0 inbound, you can mosey on down to 1600ft until intercepting the glideslope at DME 6.0 on the VOR or 5.1 on the localizer-associated DME.

But I'm not too familiar with Jepp charts. Am I missing something?
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That's exactly what I would have said.
 
HPNPilot1200 said:
I agree with the previous posts. Without referencing the VOR DME approach it would be a little confusing.
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I don't know that I've ever seen an intermediate stepdown on the outbound like that. Interesting find, Jason! That'd be a good sim approach...
 
Any ideas what a "precision reading of 0.2NM" means in the procedure notes on the ILS DME 1?

Teller1900 said:
I don't know that I've ever seen an intermediate stepdown on the outbound like that. Interesting find, Jason! That'd be a good sim approach...
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Thanks. I'm trying to locate a bunch of interesting approaches to prepare for interviews.
 
Jason,

This is an excellent example of hidden traps on approaches. In this case, it wouldn't necessarily be deadly, but on other approaches, it could be.

(I remember a crash at KCHR over this very thing)

Can you spot it?

Hint: it has to do with 9 DME.
 
Everskyward said:
The 9 DME is off MZT not IMZT.
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Exactly. Nice job.

You're in the turn and you tune to the ILS/DME and see a DME number. When it hits 9, you start down. Only problem is it's ILS DME and not VOR DME. (In an old cockpit, you would "Hold" the DME to the VOR until established.)

This missed info has caused more than one crash.

Also, another tip, since an ILS will not give you a radial from the the LOC (only which side of it you're on) track your progress with the VOR. In the old days, we did it with the NDB if it was also the OM. Use everything at your disposal.

Of course, I'm thinking old school. These new-fangled glass gizmos would never allow a crash to happen..:wink2:
 
HPNPilot1200 said:
Any ideas what a "precision reading of 0.2NM" means in the procedure notes on the ILS DME 1?
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I would assume that it requires that your DME readout be precise to at least 0.2NM vs updating only every half or one mile.
Kind of like RNP precision requirements, but for DME.
 
Kiloalphadriver said:
Exactly. Nice job.

You're in the turn and you tune to the ILS/DME and see a DME number. When it hits 9, you start down. Only problem is it's ILS DME and not VOR DME. (In an old cockpit, you would "Hold" the DME to the VOR until established.)

This missed info has caused more than one crash.

Also, another tip, since an ILS will not give you a radial from the the LOC (only which side of it you're on) track your progress with the VOR. In the old days, we did it with the NDB if it was also the OM. Use everything at your disposal.

Of course, I'm thinking old school. These new-fangled glass gizmos would never allow a crash to happen..:wink2:
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In this case if you made that error, though, you wouldn't start down too early - it would delay your descent (and your turn). But it might make it VERY difficult (or impossible) to make the turnaround within the protected space inside 11DME off the VOR.

You're right, though, as long as you have GPS/FMS and are following the line, nothing could possible go wrong! :D
 
Teller1900 said:
I would assume that it requires that your DME readout be precise to at least 0.2NM vs updating only every half or one mile.
Kind of like RNP precision requirements, but for DME.
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Makes sense. I don't think I've seen DME that only updated every half or one mile before. I'm sure they are out there...especially in Mexico.
 
In mman they give you the vor dme 3 with transition to the ils rwy 20. Mexican procedures can be tricky. vor dme 3 approach in rwy 20 as an arrival procedure until intercept altitude for the glideslope. Both courses are perfectly aligned. In this case I always set up the vor, localizer, and gps to cross check.
 
I'd say Jeppesen screwed the chart up. There is no stepdown fix outbound. D 5.1 IMZT or D 6.0 MZT defines the FAF. The vertical line extending up through the procedure turn is confusing.

The current G-1000 database does not show any stepdown outbound.
 

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aterpster said:
I'd say Jeppesen screwed the chart up. There is no stepdown fix outbound. D 5.1 IMZT or D 6.0 MZT defines the FAF. The vertical line extending up through the procedure turn is confusing.

The current G-1000 database does not show any stepdown outbound.
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I have found that the garmin database sometimes names the fixes differently from the jepp charts. However, the fix in space are both at the same place. I have only seen this happen in mexico, as in my example above. Just need to be vigilant and always have a paper or electronic chart on hand to cross check. Plus, gps overlays on vor and ils approaches are only for guidance and not for primary navigation. You get the big warning when you load the approach.
 
aterpster said:
I'd say Jeppesen screwed the chart up. There is no stepdown fix outbound. D 5.1 IMZT or D 6.0 MZT defines the FAF. The vertical line extending up through the procedure turn is confusing.

The current G-1000 database does not show any stepdown outbound.
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I see nothing wrong with this approach. D 5.1 IMZT and D 6.0 MZT are not part of the outbound procedure.Only for inbound on the approach. (This may be the source of the confusion) The vertical line is D9.0 MZT. There is no stepdown in the middle from the VOR to D9.0 MZT.

Okay, so let's say you're inbound to the VOR at 5,000. Center clears you for the ILS (or LOC), maintain 5,000 until MZT. You cross MZT and establish outbound on the 103 MZT. Once established, you can descend to 3000. At D9.0 MZT, you start your left turn and can now descend to 2500. Once you turn inbound on the LOC and you see D9.0 MZT again, you can descend to 1600 and wait for GS intercept OR D5.1 IMZT/D6.0 MZT with GS out.
 
Kiloalphadriver said:
I see nothing wrong with this approach. D 5.1 IMZT and D 6.0 MZT are not part of the outbound procedure.Only for inbound on the approach. (This may be the source of the confusion) The vertical line is D9.0 MZT. There is no stepdown in the middle from the VOR to D9.0 MZT.

Okay, so let's say you're inbound to the VOR at 5,000. Center clears you for the ILS (or LOC), maintain 5,000 until MZT. You cross MZT and establish outbound on the 103 MZT. Once established, you can descend to 3000. At D9.0 MZT, you start your left turn and can now descend to 2500. Once you turn inbound on the LOC and you see D9.0 MZT again, you can descend to 1600 and wait for GS intercept OR D5.1 IMZT/D6.0 MZT with GS out.
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I believe we are saying the same thing. It's the vertical line that Jeppesen draw too far up in the profile view that can be confusing. They didn't do that in the VOR IAP's profile.
 
aterpster said:
I believe we are saying the same thing. It's the vertical line that Jeppesen draw too far up in the profile view that can be confusing. They didn't do that in the VOR IAP's profile.
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I see what you're saying and can understand why it would create confusion. They had just too much info to stuff in between the lines and had to put it above.

One look at the plan form will show that it's not on the outbound leg.

The two views need to agree.
 
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