Established inbound on an RNAV approach
 

Apologies if this has been discussed elsewhere but I cannot find what the requirements are to be established inbound on an RNAV approach. ICAO states

“Established” is considered to be half scale deflection for ILS or VOR, within 5 deg of an NDB track.

I cannot, however, find out what is considered "established inbound" on an RNAV approach. Any help much appreciated.

Cheers

Thanks Mig, do you have a reference at all?

This seems strange as TSO-C129 does not specify a CDI scale for approach mode.

Cheers

Yep, as does my HSI, however I don't believe this scale is mandated, so it would seem strange that a descent requirement would be based off of it.

I would have thought being established inbound would some how be related to your ANP. i.e. established inbound = full scale deflection - 1/2 your ANP.

I think software holds the answer. In as much as the IAP is coded so that a fly by of the IAF triggers the the change of scale.

That's why radar vectors to the FAF should be avoided.

Interested in your move from LNAV in the question to VNAV in a following reply. Are you interested in NPA, Baro VNAV or APV?

Sir George Cayley

New(er) units provide a function to provide 'radar vectors to final' autoscaling, so this does not become a problem.
IE: done automatically.

Even my old KLN89B will provide autoscaling, once inside the final approach fix, provided a bit more input is provided prior.

Thanks all, I finally found a reference:

II-C-5-12 of the 9613 states:

"(the difference between the RNAV system computed path and the aircraft position relative to the path) should be limited to ±½ the navigation accuracy associated with the procedure (i.e. 0.5 NM for the initial and intermediate segments, 0.15 NM for the final approach segment, and 0.5 NM for the missed approach segment)."