Originally Posted by Octas8
That would be the current system Bloggs. The one where I arrive over an airfield with TAF QNH and wonder whether the place usually has a regular TAF service or not. What is the plate MDA based on? Head scratching. (Of course, local pilots would know.)
How would you have a TAF QNH for somewhere that doesn't get a TAF?
I'd suggest that local knowledge isn't a major factor. When you plan your flight you will request a TAF from NAIPS and when it doesn't give you one you will investigate why.
The worst that will happen is you won't investigate and just assume the place normally has a TAF but doesn't today. You will get there, use area QNH or AWIS QNH from somewhere within 100NM and you will add 50' when you didn't have to.