Determining LNAV\VNAV and LPV minima design and the rare case of higher LPV minima

[Tomomac33]

Hi,

Can anyone help?

I am trying to find an approved reference that explains why the scenario can arise that LPV minimas may be higher than LNAV/LNAV minimas in exceptional cases.

My understanding is that it is due to how the approaches are designed, with protected areas in relation to obstacles on the approach sector. (But will happily stand corrected)

Many thanks for people's time.
Tom

[FlightDetent]

If by LPV you mean ILS CAT II and III, I do not see how could that become the case - LNAV/VNAV being less.

[BizJetJock]

I would think that by LPV he means LPV. Why would he mean anything to do with ILS?

[underfire]

Differences usually due to the different obstacle clearance areas.

Here are some examples:

http://i66.tinypic.com/dbi3ap.jpg

LPV lower than ILS...

http://i64.tinypic.com/mic9pd.jpghttp://i63.tinypic.com/3340yzo.jpg

LNAV lower than LNAV/VNAV: (MDA vs DA)

http://i65.tinypic.com/15830xe.jpg