I was checking approach plates for LFLS today and I was a bit confused with LPV minima being lower than the ILS one. Later on I realized different MA gradients apply. Usually the plates for different types of approaches are comparable but these two just look odd to me. Who decided to make them this way and how LOC (GS out) approach has almost same or lower minima than ILS, is beyond me.
These mins are missed approach critical.
It’s because LOC has a defined MAP at which you start MisAp from MDA = higher than when initiating it from ILS mins after a dip.
It’s more academically though and often a few feet difference dictate this.
From my souvenirs of IRME, at Provence (LFML) you have something of this kind, but it’s different missed approach trajectory depending on your single engine climb gradient. We were briefing that “in case of GA single engine, we need to inform ATC that…” – typically with DA42, the MACG is around that order (2.5 to 3 depending on ).
These mins are missed approach critical.
This is clear.
It’s because LOC has a defined MAP at which you start MisAp from MDA = higher than when initiating it from ILS mins after a dip.
But how did they calculate that DA using CDFA in LOC (GS out) approach is lower than DA for ILS approach with 2.5% gradient?
Because it is assured to be laterally earlier (due to defined missed approach point)?
Because it is assured to be laterally earlier (due to defined missed approach point)?
Makes sense… so you have more time based on distance to start MA and climb earlier even with lower gradient.
But it’s not clearly stated that D0.7 SG (ML09) is MAPt at least on Jepp plate. And for CDFA and using DA instead of MDA it’s even more blurred. SIA plate is much more precise in these terms. It clearly states MAPt and doesn’t mention possibility of using DA instead of MDA on CFDA LOC approach.
But it’s not clearly stated that D0.7 SG (ML09) is MAPt at least on Jepp plate.
Edit: Actually it is – I overlooked it. Small letters – maybe I need new glasses 
Emir wrote:
and how LOC (GS out) approach has almost same or lower minima than ILS
When comparing the ILS DA with the LOC (DA/MDA(H)) with the same 2.5% missed app.clb. gradient:
The ILS approach with the “higher” DA allows for pilot decision to continue or go around AT the depicted DA, and allows (by design) for a further altitude loss (below the DA) before entering the missed approach climb segment.
The LOC only approach will be flown either as CDFA with derived DA or with a hard MDA(H) (level off = not descending below)
The LOC only, when flown as CDFA, should be used with an operators addition to the DA (commonly 50 FT additive) and you get a derived DA+50FT (in reality you DA is now 50 feet higher than depicted as DA for the LOC only approach). Looking at the aircraft approach cat A your derived DA on this approach should be 1510+50FT=1560FT(which similar to the ILS approach allows for an altitude loss before entering the missed approach climb segment).
In other words, the ILS minima (cat A) is 1534FT vs LOC only minima (cat A) derived DA is 1560FT = higher LOC minima than ILS. This is for a CDFA approach type.
If you feel like pushing it to the limit, you could skip the CDFA and dip down after 3.9NM SG to the MDA of 1510FT and continue to the defined MaP at 0.7NM SG. This approach would not allow for any descend below 1510FT (as your using and MDA). It´s a theoretical consideration, I´d be hard pressed to consider it.
The Jepp chart (11-1) has a note 1 regarding operators using LOC DA instead of MDA.
If you look in the Operators Manual (OM) part B, of the operator where you´re doing your Saab 340 Type Rating, you should find a Reference Table showing the DA addition(s) for 2D approaches or some other Operators Procedure for 2D (LOC etc.) approaches. Find below attached an example of an operators reference table.
Have fun.
Yeager wrote:
The LOC only, when flown as CDFA, should be used with an operators addition to the DA (commonly 50 FT additive) and you get a derived DA+50FT (in reality you DA is now 50 feet higher than depicted as DA for the LOC only approach).
There is no reason to have any such addition to the DA. See my blog post here: https://www.aglarond.se/wordpress/add-on-to-the-da-of-a-cdfa/
That some operators choose to have such an addition anyway is a different matter.
