A-320 RNAV limitation

[Airbussed]

Airbus has a limitation regarding RNAV approaches. It says this:

An RNAV(RNP) approach may be performed, with GPS PRIMARY not available, only if the radio navaid coverage supports the RNP value and HIGH accuracy is displayed on the MCDU with the specified RNP, and an operational approval is obtained

This sounds like I could do an RNAV(GPS) approach using say LNAV minimums without GPS PRIMARY. Is that what other Airbus drivers or former Airbus drivers understand that limitation to mean?

If so, then what RNAV system are we then using? Is it a DME/DME RNP-.3 system? In the US at least almost all RNAV approaches prohibit using that for RNAV approaches. Any input is appreciated.

[goeasy]

Yes it does mean that, as IRS navigation with DME/DME updating is reliable enough for basic GPS approach. The HIGH ACCURACY annunciation is all thats required.

Just as you can carry out a VOR or NDB approach when the aid is inop.

[Goldenrivett]

This sounds like I could do an RNAV(GPS) approach using say LNAV minimums without GPS PRIMARY. Is that what other Airbus drivers or former Airbus drivers understand that limitation to mean?
No. If the chart specifies RNAV (GPS) then you need GPS (or GNSS). If it simply says RNAV (RNP) then you don't need GPS.

See: https://www.icao.int/MID/Documents/2016/PBN%20SG2/2.PBN%20Charting%20-%20ICAO.pdf for clarification.