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I'm a new pilot working toward IFR and learning a lot of the new terms. Since English is not my native language, I was a bit confused what the actual meaning of RNP is.

I know that RNP stands for Required Navigation Performance. That sounds to me like it's talking about the performance of navigation, but not about the navigation itself. On the other hand, RNAV for Area Navigation is about navigation. How can these 2 words mean the same kind of things, if they are of different kinds?

For example, people talk about "RNP procedures". But what is a "performance procedure"? It doesn't make any sense to me. Shouldn't performance mean capabilities here, like in "CPU performance" or "performance of a computer program"? So what does a "capabilities procedure" mean?

And for comparison, "RNAV procedure" is a navigation procedure, which makes total sense - it's a procedure for navigating around.

Hot.PxL
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    Does this help? Possible duplicate. – TomMcW Jul 14 '21 at 02:08
  • When there are multiple words in a row in English, usually the LAST word is the noun and everything else is modifying it. Required Navigation Performance is Performance pertaining to Navigation, and that Performance is required. RNP Procedures are Procedures relating to the Performance of Navigation that is Required -- or to say it another way, the Procedures related to the Navigation Performance you are Required to have. – Ross Presser Jul 14 '21 at 13:08
  • FYI, the wording around the use of GNSS (GPS) is very counter-intuitive and reflects the fact that this is a very new field. Acronyms are to be placed in their historical context. This is today federated under PBN: Performance Based Navigation (meaning the navigation aid must guarantee a given position accuracy or "performance" for the procedure to be used). – mins Jul 17 '21 at 20:11

2 Answers2

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As you say in your question RNP is "Required Navigation Performance" meaning to fly a particular approach, enroute leg, arrival route, etc., your RNAV equipment must continually perform to the specification required ( for example, RNP 0.3 - position accuracy of a circle radius of 3/10ths of a NM for some instrument approaches).

So, RNP is the navigation performance requirement necessary to use a particular instrument "procedure." An "RNP Procedure" is just terminology used (by some) to describe this.

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Don't take the technical terms too seriously. Technical terms are often poor description of the item, and technical terms in English tend to be particularly bad.

These ones are fairly good for the usual standard in English. It is called “Required Navigation Performance” because there are requirements on how accurate the navigation must be (its performance) and that it has to be able to detect and alert you if it can't ensure that accuracy, and it is kind of implied there is a navigation when there are requirements for it.

For the actual definitions, see What is the difference between RNAV and RNP?

Jan Hudec
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