flyandive

Ok, time for me to jump in because if I'm confused then I know a few other people are as well.

There might be some confusion on what CANPA is so to clarify it stands for Constant Angle Non-Precision Approach. I'm not sure what the difference is between CANPA and "Real CANPA" is. It is a way to calculate a constant angle descent for a Non-Precision approach. Very rarely do you have to do much calculating since there is usually an approach angle published on the chart, yes even on LOC only charts and Jepps also have a descent rate table specifically for CANPA. In short CANPA is for Non-precision approaches. If you are thinking of VNAV then you are thinking of something different. Yes, some FMS VNAV approaches technically are still non-precision approaches making it a form of CANPA, it is not what most of us think of when we are talking about CANPA.

I did look at KSMX and BC is a circling only approach so it won't have a glide path angle on it because it is not an approach to a runway. You would either have to descend before the MAP and stepdowns to fly a straight in or just fly a circling approach. Every other LOC only plate I looked at though, did have a descent angle published as long as it was straight-in to a runway.

Lastly, it is possible to to have FMS VNAV on a LOC only plate depending on the equipment and the approach. I know this because I have flown aircraft with this capability and approval with a few caveats. You may have noticed on some approaches the note: "Only authorized operators may use VNAV DA(H) in lieu of MDA(H)." For those approaches the published MDA met DA criteria for obstacle clearance.
For the Q400 (The aircraft I have experience with) we would fly the approach as if it was a GPS approach using FMS data and an FMS calculated VNAV, however if it was properly loaded a "LOC" flag would come up indicating the FMS was showing the LOC CDI (Not RNAV CDI) and we would fly the approach to the MDA (Now a DA) before going missed which meant we would go below it during the missed approach. If that note was NOT there then we could fly the approach the same way performing all the CANPA calculations but we would have to add 50' to the MDA (Derived DA [DDA]) to ensure not going below it during a missed approach and the VNAV information was advisory only. This is very similar to how we fly CANPA approaches in the CRJ which only has advisory VNAV; hit the FAF fully configured, on speed, and begin a descent using the table on the jepp charts, about 7-800fpm until arriving at the DDA then go missed or land. If there is no table we calculate it like Rickair said.