PMDG 747X Porpoising

[Guest chrut]

So I have done my "homework" and came up with this regarding P-RNAV approaches:

Unless a published VNAV procedure is being flown, the vertical profile between two altitudes constraints is always at the pilot's discretion. However, the flight crew should aim, whenever possible, to adhere to the optimum vertical profile. Crews should recognise that there are numbers of methods by which adherence to the path can be achieved. Where a VNAV procedure is published, the flight crew are required to fly in accordance with the published constraints.

SoruceIf I understands this correctly, it means that VNAV is not required but preferred. So I think that we got it sorted out?Now, as to my main question, which was regarding "FSX wind shift" and CDA. I'll test the suggestion above by michal and try one approach without weather under the weekend and see how it goes.

[Guest chrut]

Sweden is the first country to my knowledge that have successfully used A-CDA (while other countries have used ordinary CDA) in off-peak sessions, meaning "no thrust" from CRZ to final.

Should be "no thrust from CRZ to rwy threshold". Because CDA with idle thrust from CRZ to final is a "ordinary" CDA (not A-CDA) and has been done since long ago according to this. The document, that is referenced, also shows OPS for the airport using CDAs and examples of the CDAs. None of the OPS actually require the pilot to use VNAV, but it's mentioned and the recommendation is to freely adhence to the desiered profile so that the engines operates in IDLE thrust as long as possible (wheter it be VNAV or V/S).Looking at the example flights, pages 30-31, we see a B737 using VNAV until final approach on two serperate occasions.

[Guest chrut]

For me it's always hard to maintain thrust at IDLE/HOLD from FL100 to final approach when on a "CDA STAR". From CRZ to FL100 it is better though.

This document describes preliminary pilot procedures using VNAV in a CDA starting on the page 25. Here it's shown how to handle the FL100 speed transition to 250kias.So I'm pretty much happy with this information so far and I think I have a good understanding of CDAs now. Thanks to Michael and Dan for the discussion, it has lead to a great deal of knowledge for me.