RNAV (GNSS) approach

[geirha75]

Hi

More and more major airports offer RNAV approach in thier instrumental approach charts. ENGM is one of these airports offering RNAV (GNSS) RWY for 19 R. According to an email I received from ENGM airport staff (Avinor), RNAV (GNSS) RWY 19 R approach is not VNAV certified. The RNAV approach chart is allows LNAV only. No VNAV yet. How does pilots control vertical guidance/descent down to MAPt? I'm not thinking in terms of step down descent. Can this be done using (CDA) Continuous Descent Angle by V/S down to MAPt?

I refer to following RNAV (GNSS) RWY 19 chart, ENGM:

https://www.ippc.no/norway_aip/old/AIP/AD/ENGM/EN_AD_2_ENGM_5-13_en.pdf


Sincerely

geirha75

[Mister Geezer]

In the chart you have shown, in absence of VNAV then one would revert to flying the descent profile after the FAF using V/S (or FPA if you can/wish) and aiming for a CDFA.

It's pretty straight forward stuff.

Hope that helps.

[Sir George Cayley]

Like any other non precision approach it's up to you to manage your descent profile.

With step down fixes one could be tempted into dive and drive, but constructing a descent profile based on a constant rate is safer.

If you have a WAAS enabled receiver then you'll see a form of vertical guidance derived from EGNOS, but a word of caution it won't be a true APV unless AVINOR recode the chart to include the vertical element.

SGC

[A Comfy Chair]

Geirha75,

The approach is an LNAV only approach (as you can see on the chart), but that does not necessarily mean that VNAV cannot be used to fly it. The difference between LNAV/VNAV and LNAV Only is that the lnav/vnav will generally have lower minimas, and vnav must be used.

LNAV only does not prohibit the use of vnav (if it will comply with all parts of the approach), it simply does not require it, or offer the lower minima associated with it.

Certainly most of the GNSS approaches done down in this part of the world are LNAV Only, but they are still coded in the FMC database to allow VNAV to operate correctly.

So, the answer is yes, this would be flown as a constant descent - either using V/S as you suggest, or in VNAV if the approach was coded correctly in the FMC (which it most likely is).