Snoopy wrote:
I see it exactly like 172driver. The point of this procedure is to allow ifr flights a structured arrival to a point from where it can be determined if vfr conditions exist or not.
I also agree completely with 172driver.
Another way to look at distinction between the approach terminating at the MAPt and a normal instrument approach which has a visual approach segment, Is that losing visual reference during the visual segment of an approach is NOT an emergency. It does happen and with the correct sequencing of actions conducted promptly should be a safe and normal procedure. Where as losing visual reference under VFR would be an emergency, certainly in an amongst that terrain.
I also agree completely with 172driver.
#metoo
I assume that the LOWZ RNP A procedure has been properly thought out as far as the instrument part goes, but visual part has not.
I believe someone touched upon it (though I can’t find it right now) but the requirement of switching to VFR has not been well thought out at all. The AIP plate is crystal clear that IFR ends when descending below the OCA/H.
The OCA is – even at the highest missed approach climb gradient – as high as 4690 ft. The ground elevation at the MAPt is about 2500 ft, so the height is about 2190 ft. That means that both the altitude and height are above the limits for the “clear of cloud” VMC criterion. Instead you will need 1000 ft vertical separation from cloud for VFR. In other words you must make the DA 1000 ft higher (at least 5690 ft) otherwise you would be illegal the moment you descend below the OCA! That doesn’t make sense.
@d00t has kindly in post 94 taken a photo from the MApt.
The plate states you need to be familiar with the terrain and environment, although no sign off or currency appears to be required.
It also states it is a CDFA and for climb gradient reasons the go around is initiated at DA.
I see no reason why this is interpreted as a let down procedure where identification of the runway environment is not a condition to proceeding beyond DA or MApt. The conditions for CDFA operations are clearly stated in the regulations.
The fact that there is no runway lighting is another TEM consideration.
As post 94 shows, a pilot familiar with the terrain and environment should be able to take a decision that the airport is in sight or not – if this needs visibility of 8 miles or better is another TEM factor.
While my IR in mountainous terrain has been limited to British Columbia, Italy and Switzerland I can guarantee that no approaches on a commercial op would dream of descending/proceeding beyond DA without sight of the runway environment.
In the old days you even had to count mountain obscuration lights plus the airport before descending on some coffee grinder NDB approaches into the Okanagan valley. Actually some of the old four course LF approaches were still operational as they were better than the NDB.
in a CDFA, if at DA the runway is not in sight, a go-around must be flown.
airways wrote:
#metoo
Lol……….. 
EuroFlyer wrote:
in a CDFA, if at DA the runway is not in sight, a go-around must be flown.
I wonder if the altitude is at 5400ft at MaPt which is almost 3000 above the runway elevation, what is the point of having this instrument approach?
I am not instrument rated. I somehow assumed instrument approaches help you land when you can not do it VFR but with 3000 AGL decision height, you can easily fly that approach VFR. So why bother publishing any instrument approach like that at all for LOWZ? just send them off to LOWI or LOWS etc.
By9468840 wrote:
am not instrument rated. I somehow assumed instrument approaches help you land when you can not do it VFR but with 3000 AGL decision height, you can easily fly that approach VFR. So why bother publishing any instrument approach like that at all for LOWZ? just send them off to LOWI or LOWS etc.
Because if you are in cloud or above cloud, you need a way to get under it safely. That is what the approach achieves.
This procedure is designed so that IFR traffic can fly a structured path in IMC to the decision point and then, if prevailing conditions allow, land VFR in VMC.
An example would be if your cruising altitude is FL170 and there are clouds from 11.000 feet down to 6.000 (MSL) feet.
Again, the question is why the plane ended up where it did. And then the obvious question is what decisions led to this outcome. Then those willing to can learn from this tragedy.
