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While viewing the following approach chart, which is an RNAV(RNP) CAT C Approach, there are several landing minima, stating a HEIGHT LOSS OF 50' AND 150', what does that specifically mean?

RNP APPROACH

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  • $\begingroup$ @Lnafziger - The approach is to the Antonio Narino airport in Colombia, South America. $\endgroup$ – 757toga Nov 9 '18 at 17:13
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The approach above appears to be associated with the Antonio Marino Airport, Colombia, South America: (I don't know if it is current or proposed)

Descent below the published DA/H is not permitted due to obstacle clearance requirements. Therefore, a "height loss" (amount of altitude expected to be lost during a go-around [missed approach]) is added to the minimums to account for this.

The first minimum on the chart is 6240 ft. with a 50 ft height loss added and assumes a missed approach climb gradient of 5%. The second minimum is 6340 ft. with a 50 ft. height loss added and assumes a climb gradient of 4%.

The 50 ft. added for the height loss is based on the use of a "radio altimeter."

The third minimum on the chart is 6340 ft. with a 150 ft. height loss added and assumes a missed approach climb gradient of 5%. The other minimums, all with a 150 ft. height loss added, assume missed approach climb gradients as low as 2.5%.

The 150 ft. added for height loss is based on the use of a "pressure altimeter."


The chart below is from an advanced version of "Required Navigation Performance Authorization Required (RNP AR) Procedure Design Manual" ICAO Doc 9905-AN/471

NOTE: the added height loss for "radio altimeter" use (category C aircraft) shows 71 ft on the chart below. The published height loss on the OPs IAP plate shows 50 ft. I do not know why there is a difference unless the requirements are country localized or the ICAO document has been modified.

enter image description here

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  • $\begingroup$ Good info, but what does the height loss mean? You don't mention it once in this answer (you kind of imply a meaning in the second section though). Also, how would you know what your height loss is? $\endgroup$ – Lnafziger Nov 9 '18 at 0:54
  • $\begingroup$ Right, I get that, but how do I know which set of minimums to use? The 50 ft. or the 150 ft.? $\endgroup$ – Lnafziger Nov 9 '18 at 1:09
  • $\begingroup$ @Lnafziger - I modified my answer to address your question/comment above. $\endgroup$ – 757toga Nov 9 '18 at 22:56

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