VNAV only approach

[ASHTAM]

hello
Could someone help answer this question please. Can you fly a VNAV only approach? I know you can do LNAV and LNAV/VNAV, but never heard of VNAV only, is this something you can do?

[ASHTAM]

yes...i have seen on some state charts that they publish VNAV minima approach only is this possible?? the minima is lower than a LNAV why is that

[galaxy flyer]

There has to be some lateral guidance. Any chart references

[Driver 170]

• Non-precision Approach:

– Lateral Navigation (LNAV):

– Localiser Performance (LP) minima line

• APV BARO:

– LNAV/VNAV (vertical navigation);

– SBAS:

And finally - RNP AR APCH

[wiggy]

As has been said there must be some lateral guidance... I have seen on some state charts that they publish VNAV minima approach only is this possible?? the minima is lower than a LNAV why is that

We need an example of what you are looking at but I'll offer up an example such as:

"JFK RNAV (GPS) Y 31 R"...

I'll have a stab at this but more than willing to be corrected.

1. Looking at the JFK plate (which you could do if I could paste it here) it's implicit right from the start that you are going to use ( in our case), LNAV "coupled" to GPS for the lateral mode, to comply with the RNAV (GPS) bit that is at the top of the plate and above all the minima.

2. The specific minima labelled RNAV GPS VNAV" minima (370 feet,) makes no mention of LNAV but the assumption has to be that the modes to be used are LNAV (lateral) / VNAV.

3. The " RNAV GPS LNAV" minima (460) is for LNAV plus some vertical mode other than VNAV (e.g; V/S) and is for use e..g; when cold weather takes you below the minimum uncompensatedd BARO VNAV temperature.

[aterpster]

To cite such a concern without providing the specific approach procedure is a bit suspect.

[Amadis of Gaul]

Surely, aterpster, this isn't the first suspect thing you've seen around here...

[aterpster]

Just one of many. Seems to have gotten worse though over the years.

[RAT 5]

I'm thinking pure technical; not legal nor minima, and B737NG. Could the a/c operate in VNAV & VOR/LOC or HDGSEL for either a LOC ONLY or NDB? I've never tried and not be allowed to, but they are separate channels?? Maybe next time in the sim?

[wiggy]

Certainly looks like my poorly worded effort was a waste of time - should have known better.

Somebody looking at Flt sim "plates"?

[galaxy flyer]

Ah, Rat5, the old NDB/GS approach, remember well from the days of carting checks around in a Baron with questionable radios.

[OhNoCB]

IF the question is can you use VNAV on a non precision approach whilst using VOR/LOC then the answer is yes. YOu don't need to use LNAV for it to work. This is true for a 737NG.

[737aviator]

Could the a/c operate in VNAV & VOR/LOC or HDGSEL for either a LOC ONLY or NDB?

VORLOC & VNAV is SOP for many for LOC Only approaches.

Our SOP is V/S for vertical path if HDG SEL has to be used for an approach (e.g. FMC error, bad coding, etc) however the aircraft will quite happily follow a VNAV path if its coded in the FMC if you use VNAV.

[RAT 5]

That is what I would have expected, but previous company SOP's were LNAV/VNAV or HDGSEL + V/S. I wondered why we couldn't do use VNAV for vertical. Never did get a reply. I wonder if the questioner had forgotten to include a roll mode in the question?

[Denti]

Even IAN uses something similar to LOC/VNAV, it uses LOC and GP, which is the FMC computed glide path.

[ASHTAM]

thanks all for the replies,
I can't think off the top of my head the exact airport (s) that i'm talking about but I can say one is Indonesia and the other is Denmark. I will get the exact ICAO code and procedure when i get to work tomorrow. What i can say is that i know it is an RNAV (GNSS) chart and the minima that the state is already showng is an LNAV and also VNAV only, with the minima being lower than the LNAV....

i will get the exact airport for you

[ASHTAM]

the airports in question are Denmark EKSB RNAV (GNSS) RWY 14 and the other airport is WITK in Indonesia. Both of these show VNAV only minima..

[oggers]

Hello ASHTAM

Yes you are correct. It seems different countries around the world have not standardised the way they name procedure minima on their charts. I think you can assume that VNAV minima are the same thing as LNAV/VNAV minima and apply to an APV approach using either WAAS or baro-VNAV for vertical guidance.

[ASHTAM]

thanks oggers.

[aterpster]

Here are the IAPs in question:

[galaxy flyer]

Ok, what am I missing? There's no "VNAV Only" mins as stipulated by the OP.

[oggers]

Jeppesson are not the only company that produce plates.

The OP is correct that there are plates out there with "VNAV" minima. After he/she posted it I went and had a look and found the Naviair plate for EKSB RNAV (GNSS) RWY 14 showed exactly that. So the OP should be thanked for raising a good point because the replies in this thread show that not a single poster was aware of this fact.

[Denti]

Sadly i do not have any plates for EKSB or WITK as both are not included in our LIDO route manual. However, for normal RNAV (GNSS) approaches the VNAV/LNAV minimum is depicted as VNAV with a smaller font RNAV (GNSS) above that, whereas the LNAV only one is depicted as LNAV. One could surmise that the first one would be VNAV only, however, as the approach is RNAV to begin with it has to be flown in LNAV/Managed.

[aterpster]

oggers:

Jeppesson are not the only company that produce plates.

The OP is correct that there are plates out there with "VNAV" minima. After he/she posted it I went and had a look and found the Naviair plate for EKSB RNAV (GNSS) RWY 14 showed exactly that. So the OP should be thanked for raising a good point because the replies in this thread show that not a single poster was aware of this fact.

It is reasonable to conclude that Jeppesen wouldn't arbitrarily add minimums that are not on state source (AIP). So, the question becomes: why would Navair exclude some minimums that are on state source?

[aterpster]

Denti:

Sadly i do not have any plates for EKSB or WITK as both are not included in our LIDO route manual. However, for normal RNAV (GNSS) approaches the VNAV/LNAV minimum is depicted as VNAV with a smaller font RNAV (GNSS) above that, whereas the LNAV only one is depicted as LNAV. One could surmise that the first one would be VNAV only, however, as the approach is RNAV to begin with it has to be flown in LNAV/Managed.

As you know, unlike Jeppesen, LIDO doesn't chart every IFR airport in the world. I don't believe they chart EKSB. So, that means the Jeppesen charts are probably the only that exist for that airport. Of course, they could provide tailored charts ($$$$) for some operator at EKSB.

[Denti]

I guess Navair charts are somewhat tailored to what their customers need, same as LIDO. LIDO only charts those airports that any of their custormers need, and only include those minima that are needed as well, or at least needed by some. We never have LPV minima on ours, but for some reason the LTS minima although we are not approved for that. As far as i know only very few production airline aircraft are LPV capable as standard equipment, no need to include that then.

[galaxy flyer]

very few production airline aircraft are LPV capable as standard equipment

Really? It's been standard fit on US business jets for, at least, five years. There are thousands if LPV minimum procedures.

[oggers]

aterpster

It is reasonable to conclude that Jeppesen wouldn't arbitrarily add minimums that are not on state source (AIP). So, the question becomes: why would Navair exclude some minimums that are on state source?

Well, Naviair are the state source:

"Naviair is by the Danish Transport Authority designated as AIM-office (Aeronautical Information Management) for Denmark, the Faroe Islands, and Greenland."

By inspection, it is apparent that all the lines of minima on the Jepp plate are also on the Naviair plate: LPV, LNAV/VNAV, LNAV, CIRCLING. The issue seems to be that what we are used to seeing listed as LNAV/VNAV, Naviair have called VNAV (albeit there is a 2' difference between the Jepp LNAV/VNAV DA and the Naviair 'VNAV' DA that I assume to be due to 'rounding'). Also according to the notes on the Naviair plate the "VNAV" minima are NA below -20º indicative of an APV with Baro-VNAV approach (of course if you have SBAS you will use the LPV minima).

The use of this VNAV term could simply be a mistake. Having leafed through the Danish AIP, EKSB is the only place where you find it, but it is also on the plate for RNAV 32. At other places the Naviar plates do indeed have an LNAV/VNAV line of minima. It could conform to some weird and wonderful convention that is lost on me. There also exist "RNAV" minima and "GPS" minima where one would expect LNAV.

Make of this what you will, but I reiterate the only reason we are aware of it is because ASHTAM was 100% correct in stating that such a thing as "VNAV" minima existed on some charts.

BTW, why on that Jepp plate is the LNAV minima listed as a DA(H) when it should be an MDA(H) :confused:

[aterpster]

Could you post the source charts?

BTW, why on that Jepp plate is the LNAV minima listed as a DA(H) when it should be an MDA(H)

I would guess a mistake.

[oggers]

Ok, Danish AIP here Home | AIM (http://aim.naviair.dk/)

Go to AIP Denmark>AIP PART 3>AD2 AERODROMES. They are all there.

[aterpster]

Thanks!

Chart seems clear to me. The 136 degree course line is obviously the lateral RNAV guidance. It represents both the LPV and LNAV lateral guidance.

The minimum "VNAV" obviously needs the LNAV track as well.

Or, maybe I can't see the Danish forest for the trees. :)

[wiggy]

aterpster...

Chart seems clear to me. The 136 degree course line is obviously the lateral RNAV guidance. It represents both the LPV and LNAV lateral guidance. The minimum "VNAV" obviously needs the LNAV track as well.

Maybe I'm missing the forest as well but I agree. As mentioned way back earlier there are other charts out there from other providers for other airports that do not specifically say "LNAV/VNAV" on the minima table, just VNAV but it is implicit from e.g. the chart title ( and other notes) that LNAV or similar is providing lateral guidance since it is an RNAV GPS approach.

[aterpster]

Yet, EKKA, RNAV 27 has LPV, LNAV/VNAV, and LNAV. Also. Jepp shows DA for LNAV only. I guess Denmark permits using MDA as DA for approved operators.

[Denti]

Its an EASA requirement. All NPAs (with very few exceptions) have to be flown in CDFA with a DA, not an MDA anymore.

[RAT 5]

In which case is there anyone out there who is still adding 40 or 50' to charted decision alt? I ask because a previous XAA, even after minima were designated DA still required the additive. Never did find out why. This was the case for an MDA, but that's different.

[OhNoCB]

For the charts we use anyway, whenever they moved from MDA to DA on NPA plates, literally all they did was change "MDA(h)" to "DA(h)". The values never changed and therefore there is no allowance for dipping below that value in the go around like there is with an ILS "DA". For this reason we add 50' to cover this scenario. I imagine the chart creator doesn't want to add this value themselves to make a 'true' DA because they value to be added really varies depending on the aircraft - momentum suggests that a C150 going around is unlikely to lose the same altitude as an A380.

[galaxy flyer]

If the correct survey is done (can't recall the plane--1:34?) there is no need to add to the DA. FAA World, that us.

[aterpster]

Two surfaces are measured inside the VDP (or the point where a VDP would be if there is not one) 34:1 and 20:1. Jeppesen is slower on charting this than the FAA. On FAA charts the 34:1-clear is marked by a light grey fan in the profile view that originates at the runway.

[G-V]

For the charts we use anyway, whenever they moved from MDA to DA on NPA plates, literally all they did was change "MDA(h)" to "DA(h)". The values never changed and therefore there is no allowance for dipping below that value in the go around like there is with an ILS "DA". For this reason we add 50' to cover this scenario. I imagine the chart creator doesn't want to add this value themselves to make a 'true' DA because they value to be added really varies depending on the aircraft - momentum suggests that a C150 going around is unlikely to lose the same altitude as an A380.

It appears that Jeppesen changed the way they treat DA and MDA. See below: