Approach chart minimun altitud interpretation
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EMB170:
Well, no segment of that IAP has a steep descent.
Here is another base leg course reversal over the same airspace. Seems like it should be 1,700 too, based on your assessment.
Looking at the jepp chart, i would descent to 1700' if i'll do the procedure and, step descent to 2200' if i'll approach from TBG.
Looking at the chart it looks to me that the island where the TBG stands on is 1007' high and that is the reason for the step descent.
Looking at the chart it looks to me that the island where the TBG stands on is 1007' high and that is the reason for the step descent.
Here is another base leg course reversal over the same airspace. Seems like it should be 1,700 too, based on your assessment.
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ILS RWY 3R Descent gradients/angles:
TRG to TBG 8.0 DME:
112.5 feet per mile, 1.06 degrees
TBG 80.DM (or INAT 11.0 DME) to LAMBI non-precision FAF:
83.33 feet per mile, 0.79 degrees
To P-FAF:
86.60 feet per mile, 0.82 degrees
TRG to TBG 8.0 DME:
112.5 feet per mile, 1.06 degrees
TBG 80.DM (or INAT 11.0 DME) to LAMBI non-precision FAF:
83.33 feet per mile, 0.79 degrees
To P-FAF:
86.60 feet per mile, 0.82 degrees
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In this example there are two separate and unrelated ways to position onto the ILS.
1. The simple option:
From TBG at 3100ft establish outbound on the 037 radial and when established descend to 2200ft. After intercepting the LOC at d11 INAT descend to 1700 and further when established on the glide at d5 INAT (LAMBI)
I think that everyone agrees with that so lets remove that from the chart leaving us with;
2. The not so simple option (or so it seems).
From LMM (or TUM) proceed outbound on R186.
How far do you go out? - You can turn in whenever you want but you must remain within 10nm.
So let's fly a nice approach.....
We fly outbound on the 186 from LMM until d7 INAT and we make a right turn to establish inbound on the LOC at d7 INAT.
This is perfect because we have exactly 2nm from establishing on the LOC until GS intercept.
If I don't descend to 1700ft during the outbound and turn I am not going to be well positioned for a safe stable approach when I establish inbound on the LOC at 7d
Please note that while I start and end the inbound turn at d7, during the turn I will be further out. This is OK provided I comply with the (poorly) charted requirement to remain within 10d when doing the tear-drop or base turn.
However, if I find myself establishing on the LOC at D11 INAT I must during the turn have exceeded the requirement to remain within 10nm of LMM.
1. The simple option:
From TBG at 3100ft establish outbound on the 037 radial and when established descend to 2200ft. After intercepting the LOC at d11 INAT descend to 1700 and further when established on the glide at d5 INAT (LAMBI)
I think that everyone agrees with that so lets remove that from the chart leaving us with;
2. The not so simple option (or so it seems).
From LMM (or TUM) proceed outbound on R186.
How far do you go out? - You can turn in whenever you want but you must remain within 10nm.
So let's fly a nice approach.....
We fly outbound on the 186 from LMM until d7 INAT and we make a right turn to establish inbound on the LOC at d7 INAT.
This is perfect because we have exactly 2nm from establishing on the LOC until GS intercept.
If I don't descend to 1700ft during the outbound and turn I am not going to be well positioned for a safe stable approach when I establish inbound on the LOC at 7d
Please note that while I start and end the inbound turn at d7, during the turn I will be further out. This is OK provided I comply with the (poorly) charted requirement to remain within 10d when doing the tear-drop or base turn.
However, if I find myself establishing on the LOC at D11 INAT I must during the turn have exceeded the requirement to remain within 10nm of LMM.
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DFC:
Well put.
I checked with Jeppesen and, indeed, you have to read the chart in two components, just as you have. Because the base leg turns "in front of" the 8.0 DME TBG/11.0 DME INAT, the 2,200 applies only to the initial approach segment from TBG to that fix. So, indeed, 1,700 is the base turn minimum altitude.
I'll attached the Jeppesen response later, which includes the source. Jeppesen has no idea why Panama included the three ball-noted altitudes as recommended altitudes. They are, in fact, minimum altitudes.
In this example there are two separate and unrelated ways to position onto the ILS.
1. The simple option:
From TBG at 3100ft establish outbound on the 037 radial and when established descend to 2200ft. After intercepting the LOC at d11 INAT descend to 1700 and further when established on the glide at d5 INAT (LAMBI)
I think that everyone agrees with that so lets remove that from the chart leaving us with;
2. The not so simple option (or so it seems).
From LMM (or TUM) proceed outbound on R186.
How far do you go out? - You can turn in whenever you want but you must remain within 10nm.
So let's fly a nice approach.....
We fly outbound on the 186 from LMM until d7 INAT and we make a right turn to establish inbound on the LOC at d7 INAT.
This is perfect because we have exactly 2nm from establishing on the LOC until GS intercept.
If I don't descend to 1700ft during the outbound and turn I am not going to be well positioned for a safe stable approach when I establish inbound on the LOC at 7d
Please note that while I start and end the inbound turn at d7, during the turn I will be further out. This is OK provided I comply with the (poorly) charted requirement to remain within 10d when doing the tear-drop or base turn.
However, if I find myself establishing on the LOC at D11 INAT I must during the turn have exceeded the requirement to remain within 10nm of LMM.
1. The simple option:
From TBG at 3100ft establish outbound on the 037 radial and when established descend to 2200ft. After intercepting the LOC at d11 INAT descend to 1700 and further when established on the glide at d5 INAT (LAMBI)
I think that everyone agrees with that so lets remove that from the chart leaving us with;
2. The not so simple option (or so it seems).
From LMM (or TUM) proceed outbound on R186.
How far do you go out? - You can turn in whenever you want but you must remain within 10nm.
So let's fly a nice approach.....
We fly outbound on the 186 from LMM until d7 INAT and we make a right turn to establish inbound on the LOC at d7 INAT.
This is perfect because we have exactly 2nm from establishing on the LOC until GS intercept.
If I don't descend to 1700ft during the outbound and turn I am not going to be well positioned for a safe stable approach when I establish inbound on the LOC at 7d
Please note that while I start and end the inbound turn at d7, during the turn I will be further out. This is OK provided I comply with the (poorly) charted requirement to remain within 10d when doing the tear-drop or base turn.
However, if I find myself establishing on the LOC at D11 INAT I must during the turn have exceeded the requirement to remain within 10nm of LMM.
I checked with Jeppesen and, indeed, you have to read the chart in two components, just as you have. Because the base leg turns "in front of" the 8.0 DME TBG/11.0 DME INAT, the 2,200 applies only to the initial approach segment from TBG to that fix. So, indeed, 1,700 is the base turn minimum altitude.
I'll attached the Jeppesen response later, which includes the source. Jeppesen has no idea why Panama included the three ball-noted altitudes as recommended altitudes. They are, in fact, minimum altitudes.
