LNAV/VNAV@VNAV minima difference
 

What the difference between these minimums? Thanks

The TEMPO one has a 3.2deg glidepath, which probably clears more obstacles than the 3deg one, hence lower OCA/DA?

It’s the difference between a 3D (LNAV + VNAV) and 2D (LNAV + V/S, FPA, etc.) approach. With LNAV/VNAV you have lateral and vertical path guidance but with LNAV you are only getting a lateral path, hence separate minima.

There is also the steeper approach on the noise abatement trial procedure, which will have a different obstacle profile, as FlyingStone points out. The LNAV minima are the same as you are not using vertical guidance.

I mean the same type of minima is called on on chart VNAV and on another one LNAV/VNAV. Why?

There is no difference. It may be typographical error or a naming convention change. On the equivalent Jeppesen plates they are both referred to as LNAV/VNAV.

Look at the change in Circling minima, there’s a close in obstruction. LNAV minima will assume a dive and drive type approach where as the LNAV/VNAV will give a glide path with a corresponding obstruction clearance surface which may clear obstructions in the LNAV only area.

LNAV+V and LNAV/V (depending on brand of electronic wizardry) is the difference between advisory and mandatory guidance.

The newer, TEMPO chart, refers you to AIP SUP 40/2019 - https://www.aurora.nats.co.uk/htmlAI...040-en-GB.html
The SUP actually includes the charts and there it says, from the CAA mouth direct OCA(H) for LNAV/VNAV.

But already you knew that.

Neither of which explains what was the reason for VNAV label on the previous version RNAV (GNSS) Z. Checking with the AIP again, https://www.aurora.nats.co.uk/htmlAI...ics/124009.pdf the CAA called it LNAV/VNAV already there.

Apparently the nice LSY people for some reason changed the labelling on the original chart, but not on the TEMPO one.

https://cimg1.ibsrv.net/gimg/pprune....96fc60b891.png

Voila. In LSY graphical language There are 3 different methods how they depict the same minima (my screen is from the LAT chapter, also available to you in FIV under the "Manuals" link from the top-level menu).

He’s not asking about LNAV vs LNAV/VNAV, he’s asking why on one plate the LNAV/VNAV minima is referred to as just VNAV.

:ok: That is true. Thanks

My idea is that an LNAV/VNAV minima , is a procedure based on GPS signal not corrected by ground station,
VNAV ( or Baro-VNAV ) is an APV procedure ( Approach with Vertical Guidance ) flown with reference to baro altitude , hence the need
for higher minima.

That seems at odds with the reason for UK AIP SUP 40/2019 as well as the chart producer's explanatory guide on minima box labelling.

Both charts in the AIP have LNAV/VNAV designation on them. Only the LIDO re-draw of those has the sleek looking (and confusing) version on the older chart.

Unusually, I find myself in agreement with Flight Detent. The LIDO legends and tables section will tell you the LNAV/VNAV and VNAV are the same type of approach - RNP approach based on LNAV and VNAV guidance.

rgds

The temporary chart is to be used when issued by ATC. My guess is a crane that is not always extended.

In this particular case, it is a live operational trial of a steeper angle procedure, while the old RNAV-Z use is suspended.

Not sure if anyone's mentioned it here yet, the details are available from the full AIP SUP for this [UK 40/2019]

Do you use Vert RNP 125 when flying LNAV minima, using LNAV/VNAV minima the aircraft is to be within +/- 75' of profile in the final approach segment, the UK (Standard Doc 24) says this applies to both 2D & 3D approaches EASA doc's are clear on this when flying LNAV/VNAV minima but I can't see/find clarity on the required tolerance on 2D and I know some 737 European operators don't use 125 for RNP flown to LNAV minima (CDFA) using either VNAV or V/S

They're the same

ICAO has now standardised the naming of RNAV approaches to stop the confusion. LNAV/VNAV won't be a term used, but instead just VNAV.