RNP 1 vs RNP APCH
 

Hello,

I'm a bit confused by the difference between RNP APCH and RNP 1, particularly in terminal areas. If the aircraft is RNP APCH certified, it must have a navigation accuracy of +/- 1 nm in the initial and intermediate segments, and +/- 0.3 nm in the final approach segment.
However, reading about RNP 1, it's also for terminal areas.

So, is it possible that an aircraft is certified for RNP APCH and RNP 1, and what does "terminal area" mean in this context ? I can fly an approach but can't fly in a terminal area ?

Thanks in advance for any insight

https://www.eurocontrol.int/sites/de...-pbn-a-rnp.pdf

Look at page 6, or just read the entire document :)

Have a look at the diagram on page 13 for that one.

The PBN navigation specifications, like RNP 1 or RNP APCH, are applied to particular routes or procedures, not volumes of airspace. So a SID or a STAR might be RNP 1, and a GPS approach will be RNP APCH. Both may be "in the terminal area". Aircraft are certified for multiple navigation specifications.

Going back to the original question, an aircraft certified to RNP 1 only (say a G1000 without SBAS) would be able to fly a SID based on GNSS guidance, but would not be able to fly an approach, so going to an airfield it could fly the STAR using GNSS but would have to switch to another form of guidance for the approach. I found an overview of PBN codes related to Garmin equipment in Diamond aircraft here: https://www.euroga.org/forums/mainte...quipment-codes
Looking at this, any equipment with RNP APCH capability is also capable to use the 'lower' RNP categories. If you don't have the full PBN capabilities available in a specific aircraft, it would not keep you out of a certain piece of sky, but it would keep you off the specified procedures and force you to use other routes/approaches.

That's a reasonable rule of thumb, but is not strictly true, as some of the nav specs with higher numbers have other requirements beyond accuracy/integrity. An RNP APCH aircraft is not, for example, always (or even usually) certified for RNP 4, as the latter has requirements for redundancy.

Exactly.

Thanks for the correction. I did base it on the Diamond/Garmin overview that I found so it may not cover every possible configuration. My statement as you quoted it should probably be amended to "any equipment with RNP APCH capability should in most cases also be capable to use the 'lower' RNP categories."