I must admit its the first time I hear something about this procedure.
I haven`t flown IFR for quite a while now but when was this procedure introduced? I have never seen an approach like this on the charts I used. (or maybe overlooked it)
Nevertheless, although I don't see anything wrong with the procedure, I can't find the big (or even a small) benefit.
212man, I use your post to explain my point of view.
Correct me if I missed or misunderstood something.
We add 50 ft to the MDA and treat it as a DA (ala FW) though, depending on the location of the MAPt and the VPATH coding, the MAPt may come first. Every approach is thus flown in the same manner with the same sight picture at the bottom - ILS, NDB, VOR, RNAV. Many NPA approaches are now approved - and published - as allowing the MDA to be used as the DA. This reflects the fact that the approach is being flown at approx 3° (5.2%), rather than the assumed 15% gradient used for OCH calculations by ICAO Doc 8168.
As long as I stay above the MDA I can (legally) descend / climb however I want!? The MAPt defines the point I have to start the climb out (at least) and the MAP. (I can start the climb way before the MAPt but have to track to the MAPt to start the MAP in regards of turns etc.)
So why do they have to be approved for this?
The fundamental misunderstanding amongst many pilots who argue against this concept is that somehow the MAPt relates to the ability to land from the approach - it does not.
The MAPt is the first point from which the Missed Approach Criteria are defineable, and in no way implies that a safe approach can be made from - or just before - that point.
Consider an NDB approach, with the MAPt at the NDB in the mid-field with an MDH of 650 ft - how can you safely conduct an approach and landing from that point? Dump the collective, and practically enter autorotation? Turn downwind and descend - back into IMC possibly?
The following applies for day operations:
Consider clouds broken at 650ft. You fly the 3° approach and there is this cloud layer right at the place you reach your "DA". You see nothing
(at 700ft!, cause you added 50ft for the DA. You are allowed to dip under the DA but you are not allowed to plan it. Actually, the approach would be a waste of time, because you already know you won't become visual before you start the approach) and start the MAP (or at least the climb).
The second in sequence is a guy flying the "dive and drive" procedure.
Lets assume the clouds did not move to give both the same situation.
After a quick (no autorotation of course) descent he reaches the MDA far before the MAP. He starts to cruise at 650ft and (because of the BKN cloud layer being at 650ft) he is lucky to find a "hole" in the clouds, descents further below MDA (now visual) and performs a visual approach.
Now lets assume he did not get visual on his way to the MAPt but gets visual at the MAPt. (The NDB is midfield) He descents below the MDA as far as possible (remains the required ground clearance) and performs a circling approach.
Visibility requirements should be considered, too. If you don`t find the requested VIS you start the MAP even if you are outside the clouds.
I understand your point, but we are still in the helicopter section, aren't we?
Circling with a helicopter is... well... not that difficult. You can slow down legally to 60 KIAS (CAT H) or 70 KIAS (CAT A).
Again, in my eyes its legal but not really practical or even safer.