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RNAV (GNSS) Approach Operations - LNAV and LNAV/VNAV

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RNAV (GNSS) Approach Operations - LNAV and LNAV/VNAV

Old 27th Apr 2015, 18:28
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RNAV (GNSS) Approach Operations - LNAV and LNAV/VNAV

These are sometimes called RNP Approach Operations, they are GNSS-based and flown to minima labelled LNAV and LNAV/VNAV on a chart titled RNAV/GNSS.

LNAV approach operations are flown on Non-Precision RNAV(GNSS) procedures which are charted to a Minimum Descent Altitude (MDA).

LNAV/VNAV approach operations are flown with vertical guidance from the aircraft's barometric altimetry system (Baro VNAV) on an RNAV (GNSS) approach procedure, and are charted with a Decision Altitude (DA).


Just need to some help on this, at EPGD minimums are 1060 for RNAV RWY 11 phase 2 TEMPO

LNAV Cat C 1060 - so does this mean this minimum is an MDA and can't be flown in VNAV? So this approach or any approach with LNAV only means its a 2D approach with no vertical guidance. Non APV !

But EU-OPS only allows CDFA so what other options do i have for vertical guidance... IAN ? V/S ?

I did engage VNAV and the acft started to descend at the FAF, FMA showed VNAV PTH. So it seems my FMS had the GP coded in for BARO VNAV. So why does the chart or any other say LNAV?
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Old 27th Apr 2015, 19:01
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LNAV only, treat it as a MDA and add your company addition to the altitude given. Fly it vertically as you wish, V/S or VNAV depending on your company SOP. Do you not fly VOR/NDB approaches with VNAV in your company? If the GP angle in your FMC doesn't agree with the chart then that'd be the only reason I'd choose to fly it in V/S.

If you have LNAV/VNAV minima then treat it as a DA and flying it in VNAV is mandatory.
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Old 27th Apr 2015, 19:22
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Sorry i'm not in the aviation industry just have my own 737 NG build!

So +50 on my MDA then fly the RNAV app in LNAV and V/S as it only mentions LNAV for the approach and not LNAV/VNAV.

LOC app i use LOC and V/S or IAN

VOR - NDB is LNAV/VNAV or IAN
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Old 28th Apr 2015, 00:45
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In my company that approach would be flown in APProach mode (IAN) and the DA treated as what it is, a DA. Since 2011 there are no MDAs in europe anymore, however you have to check with your company if you need to add anything to the published DA, in our case we don't.

Baro VNAV operations might make it possible to have a lower minimum, however only down to a certain temperature which should be mentioned on the approach chart. The procedure is the same as for a non-VNAV minimum, however for the non-VNAV minimum we have to use temperature corrections for temperatures of 0°C or lower, for Baro VNAV we don't have to do that unless the temperature is below the minimum approved for that approach.
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Old 28th Apr 2015, 13:16
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I have IAN with my NG so selecting this with an RNAV app with LNAV only will still build a GP from the RWXX point on the legs page? So why doesn't it just say LNAV/VNAV if a GP still can be created?
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Old 28th Apr 2015, 19:29
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One thing is the approach, constructed by the authority, having in mind not only 737s and A320s but all the other types that will probably use that airport as well. The other thing is the aircraft capability. Both 737 and A320 can fly RNAV approaches fully managed/IAN, and it doesn't matter what the approach minimum is based on. One has just to be aware how to use the minimum in low temperatures and which one to use in which situation.

If you have the approval you can fly all approaches in APProach mode on the 737 using IAN, depending on FMC setting either as precision approach (ILS/GLS/MLS) or NPA (all the rest except RNAV RNP (AR)).

For example the EDDB RNAV (GPS) 07L has a Baro VNAV minimum of 490 and a LNAV minimum of 630. The Baro VNAV is available down to -15°C, below that you cannot use it anymore and have to use the temperature corrected LNAV minimum. Yet the approach can be flown using the same procedure, it is the same approach after all, just different minima depending on aircraft equipment.
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Old 29th Apr 2015, 20:26
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Ok thanks alot! So LNAV mins are temp corrected so why can't they be lower?
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Old 30th Apr 2015, 00:56
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so if temp goe below -15 you can use the LNAV minimum as this has been corrected. So what GP are you using then if you switch from BARO VNAV as this is useless below -15 ?
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