Peter_G wrote:
Hope this helps.
It did work! Thanks very much Peter!
I’ll try to find a way to “bulk import” several plates at once, and not have to do it individually. It will come down to locating the folder where SD stores the plate, but iPads are not where “file explorer” friendly.
Ibra wrote:
I will post when that works…
Please do! :)
Ibra wrote:
DH = OCH+50ft
Where do you get that one from?
Assuming NCO: Your DH / MDH is the higher value of the OCH and the system minimum (which is – simplified! – 200 ft for a 3D-approach oder 250 ft for most of the common 2D-approaches except NDB). On many 2D-approaches the OCH is higher that the system minimum, so no need to add anything here.
Just crude approximation for GA flying, of course there is system minima, do you have some IFR plates where OCH is bellow 150ft for ILS Cat I approach and 200ft for GPS approach?
Ibra wrote:
Just crude approximation for GA flying,
But why not simply set DH = max(200,OCH) for an ILS or LPV200.
of course there is system minima, do you have some IFR plates where OCH is bellow 150ft for ILS Cat I approach and 200ft for GPS approach?
Yes.
Airborne_Again wrote:
But why not simply set DH = max(200,OCH) for an ILS or LPV200
That’s also a simplified version as well and you are assuming to have an ILS or LPV200
My point it’s hard to fill up all those one pager of formulas while hand-flying flying after a runway change or given a new approach
- If one has the Jepps plate you read the number round it and spend more mental effort flying it
- If one get an OCH number add 50ft round it and spend more mental effort flying it (you can check calcs on the ground)
On typical GA flying (down to 200ft DH), system minima & OCH are tightly linked and highly correlated anyway, things will only start to diverge bellow 200ft where one pager of complicated minima formulas would be very useful…
Airborne_Again wrote:
Yes.
ESNZ ILS 12
Yes you are right ESNZ ILS 12, the minima would be wrong by 10ft
Blackpool ILS28 as well, the minima will be wrong by 7ft
I can’t fly those levels of precision !
Ibra wrote:
My point it’s hard to fill up all those one pager of formulas while hand-flying flying after a runway change or given a new approach
- If one has the Jepps plate you read the number round it and spend more mental effort flying it
- If one get an OCH number add 50ft round it and spend more mental effort flying it (you can check calcs on the ground)On typical GA flying (down to 200ft DH), system minima & OCH are tightly linked and highly correlated anyway, things will only start to diverge bellow 200ft where one pager of complicated minima formulas would be very useful…
So your point is that it is difficult to compute the (M)DA in your head when the OCH is below system minimum? There’s some truth in that, although I don’t think that you solve that problem by adding 50’ to the OCA.
Yes you are right ESNZ ILS 12, the minima would be wrong by 10ft
Blackpool ILS28 as well, the minima will be wrong by 7ft
I can’t fly those levels of precision !
Well, you asked for it – I provided it!
Anyhow, you should be able to determine when you’ve reached the DA with a precision of 10 ft. We’re not talking level flight at the MDA during a dive’n’drive approach.
Airborne_Again wrote:
although I don’t think that you solve that problem by adding 50’ to the OCA
Just need some improvements: some linear regression of (M)DA vs OCA on all GA IFR plates
The key thing is still having an (M)DA and flying it…
Well, methinks that determining a DA/MDA on an instrument approach in IMC is not the right place for using rules of thumb to begin with. And, IMHO there is no reason for doing so. I am using government plates with just OCH‘s on it for my personal flying, and all I do is adding the system minimum to the threshold elevation and then check to see if the OCH is more restrictive.
But you are correct when you say that any error that gives you a lower minimum with you method is small in most cases. On many 2D-approaches, however, you are wasting 50 ft that way.
Maybe start a new thread here? Seems to be quite a bit off-topic discussion last few days.
Ibra wrote:
I need to try adding some GPS and naming meta-data to the PDF to help Georef by SkyDemon and get selected in “MakeApproach”
I will post when that works…
Just an FYI, maybe this thread in the SD forums is helpful: