RNAV LNAV/VNAV approach problems

[Copper. 78]

Quite right leads to much confusion. The confusion led to me making that chart, which is obviously outdated but somewhat useful still in illustrating the RNAV paradigm.

 

"EOSID", another spec which goes under "RNAV RNP APCH" along with the purple boxed "RNAV (RNP)".

 

Great explanations Simon.

[VHOJT 166]

Hi all,

Firstly, sorry for not replying for a day or two.  I don't want it to appear at all that I don't appreciate your responses.  Secondly, thank-you all for your input and help, and for turning it into a very interesting thread.

This whole RNAV and RNP nomenclature can get very confusing.  I also mis-labelled the approach - it should have been RNP 0.3 - it's actually termed on the document as an RNAV (GNSS) approach.  Brian's diagram is also very useful.

Simon, your through explanation of the various traps is much appreciated.  Thanks for taking the time to write that.  It's good to have you around these forums.  I never thought of modifying that VNAV speed in the FMC before closing the MCP speed window.  I'm going to give your and Wing's suggestions a go, and maybe HDG select around that corner, as well as V/S until approaching the FAF before I re-engage VNAV.

I'll give this a go on Friday night or Saturday and report back - I might even make a video if I can figure out how.

All of you - thanks very much!

Cheers,
Rudy

 

[sp0701 1]

Love when this happens

https://gyazo.com/1fc4abf575c602185bf116e5621cca6a

[1290SASRider 26]

12 hours ago, sp0701 said:

Love when this happens

https://gyazo.com/1fc4abf575c602185bf116e5621cca6a

Just flew ORD-LEJ last night in the 777F (virtually).  Leipzig was and is one of my favorite cities!

This has been a great thread to follow.  Usually in ground school this was about the point where the after-lunch "food coma" kicked in as it is not the most riveting stuff to learn but it is clearly important to understand well.

[JC75 22]

Yes the naming especially across varying states, and the fact the regulation, for all of it is an ever evolving situation doesn't make it easy to understand. Although quite a bit of work is being done on this now to try and bring it aligned across the globe. There also quite a bit of regulation occurring on the requirements to make more aircraft and specifically airports to be equipped with SIDS/STARS/Transitions and Approaches to an RNAV standard. Ultimately the faster they can get this done and enforce the regulation the better for the industry, and equally some sense with the ability to fly GBAS to CAT3 will come. (which is why I have previously commented I'm surprised that PMDG are not doing more to update their FMC and nav database format to allow for proper use of RNP AP and RF legs which the other aircraft are equipped and capable of doing.

 

That aside I also have to agree the 747 LNAV performance is somewhat questionable, it seems to struggle to follow many SIDS and STARS, even conventional ones, often missing turns, leaving them late and then overcompensating at a strange place, in fact to such a high occurrence I'm surprised this ever made it through Beta testing.

Some of the other aircraft aren't perfect either, the 737(although haven't tested it recently since the upgrades) often enters holds incorrect, etc. 

 

To be fair I think the last aircraft that I saw do LNAV/VNAV following the best was the PIC767(the first version) which had it totally perfect.