I originally put ??? in that box and then decided to be provocative.
I am very happy with now being able to teach that LPV200 is a PA, and refer to “the guy who wrote the PBN learning objectives”. Then I may or may not include his reference – a chat with a random pilot who thought it would be cool to regard the LPV200 as PA 
I believe the test standards for IR skill tests still require applicants to descent on NPA’s to MDA(H) +100/÷0 ft during missed approach, ignoring the fact that most NPA’s these days have DA’s attached.
There is a fair bit of “history” attached to adding 25/50/whatever to the MDH. One FTO examiner I used to fly with told me these add-ons were implemented by the FTO industry, along with – he said – the 170A flight test, to improve first time IR test pass rates When I did my JAA IR initial test, 2012, the examiner asked me whether my POH had an altimeter correction; I showed him that it did not, and he said I may therefore go around at the published Jepp minima.
huv wrote:
In my experience, the widespread uncertainty is whether a non-precision DA can be treated as such, i.e. as a DECISION altitude, not a zero tolerance altitude, originally called a minimum descent altitude – or if you can go below DA on the missed approach, just like everybody agrees you may on an ILS. If not, then what is the point of naming it DECISION height?
The difference between MDH and DH is not about whether you can go below it. I personally don’t believe you can legally go below it under the FAA system unless you are approved to treat mda as dh using opspec 073.
A DH is is a height at which you must make a decision. If you fly a CDFA you need to make a decision at an altitude before the glidepath would take you below the MDA/DH. It is a point in space, a decision must be made there.
If you fly a D&D approach you can fly the MDA until the Missed approach point. You have a period in which you can decide to land or go missed.
JasonC wrote:
A DH is is a height at which you must make a decision. If you fly a CDFA you need to make a decision at an altitude before the glidepath would take you below the MDA/DH.
Then what is the point in changing name from MDH to DH? To me as pilot looking at the plate I need to know whether I have to make a decision at that altitude (which will take me a few feet below during the missed) or whether the number is a hard minimum. Those two used to be DH and MDH, respectively. Now the pilot looks at a DH number and wonder, hmmm, is this the old kind of DH, where I make the decision at the DH; – or is it the new CDFA kind of DH, where the DH is not a real DH, but a number that I should treat like I used to do with MDH’s – a hard minimum?
No, my impression is that Jeppesen plates for 2D approaches show MDH and 3D approaches show DH.
huv wrote:
No, my impression is that Jeppesen plates for 2D approaches show MDH and 3D approaches show DH.
And what about the EDSB chart in this thread (LNAV —> DA ?
@huv you are asking as if I personally made the change. It is the way Jepp does it with CDFA LNAV approaches. I think because this is also the way CAT want it depicted. I am not trying to defend it just explain what I think it shows.
If it is an LNAV ( including +V) NDB or VOR I treat it as an MDA, if LNAV/VNAV or LPV or ILS I treat it as a DA.
My experience is that Jepp plates show DA even for the most old fashioned NPAs. NDB at LFAC Calais is possibly the best example. Horrible timed NDB approach with the NDB off airfield, no DME, no FAF, yet the Jepp plate still gives us a DA at MDA.
NCYankee wrote:
A simple example where the LNAV might result in a lower MDA than a DA is the case where there is an obstacle that once passed, the LNAV permits placing a step down fix to descend to a lower MDA. With a GS, only one angle is permitted and step downs can’t be used to advantage.
I have seen this argument in a number of contexts, including the rare example of where an obstacle penetrates the LNAV+V glidepath between the MDA and the threshold.
Please could someone explain simply why the obvious solution is not simply to steepen the slope all the way down? After all, if you have to fly a steep slope in the last segment, it must be better for it to be stabilised over several miles than to be a sudden transition close in?
bookworm wrote:
The current Part-NCC and Part-NCO implementing rules allow you to do this, even though the GM discourages it.
Is that right about the GM?
GM1 NCO.OP.110 states:
An acceptable method of selecting aerodrome operating minima is through the use of commercially available information.
Which seems to say that Jepp is King, and Jepp says DA=MDA.
More specifically, GM7 NCO.OP.110 says:
An SAp (Stabilised Approach) will never have any level segment of flight at DA/H or MDA/H, as applicable. This enhances safety by mandating a prompt missed approach procedure manoeuvre at DA/H or MDA/H.
Which seems to suggest that that the missed approach is started (albeit promptly) at DA/H or MDA/H and therefore not necessarily before.
