Flight Visibility on non-precision approaches
 

I am familiar with determining flight visibility on precision approaches with being able to see the decision bar from and a couple of additional lights to confirm I have 1/2 mile flight visibility. But how do you determine flight visibility on non-precision approaches, especially when your decision point is the VDP? Every article I find online references precision approaches only.

you are over thinking it. VDP IS a visual descent point, if you are in a position to land and have the runway in sight at the VDP continue the descent and land. If one of those 3 are not met, go missed. If you are beyond your VDP, you will probably not be able to complete a stabilized approach and landing anyway. Provided you have the environment in sight at the VDP, you will have the flight visibility in all real world situations.

in what real world, actually-happened, situation has anyone asked you, to you yourself come up with "flight visibility"

(unless after landing and "what do you estimate the visibility" from ATC)

ever?

If one were to exercise one's part 91 option to go down and take a look, and the official vis was reporting too low, it's conceivable that you might need to explain your flight vis. Or if RVR dropped after the marker for 121.

But if the official reported vis is good, then it should never be an issue.

when regional interview gouges stop mentioning stuff like this, or once I'm past that phase of my career, I'll let it go

If you're at minimums, your only concern is 'do I see the runway environment and can I descend from MDA?' If you have the approach lights, you can descend 100' below, and if you have the runway, come on down. That's not the time to be guessing what the visibility is. You needed the appropriate legal visibility to start the approach. To finish it, you need to be able to see the runway environment.

I believe JohnBurke's response above summed things up correctly.

Practically I agree. Technically you might need published vis.

But after-the-fact there might be situations where it would be beneficial to articulate how you estimated flight vis, if you choose to put yourself in such situations.

What am I missing here?
Isnt this where you just use the 3:1 rule?
If the minimums are 400 (AGL) the VDP is at 1.2 NM so if you see the runway at VDP the visibility is……..mathematically slightly more then 1.2 and for all practical purposes a mile.

As defined by the FARs, Flight Visibility means the average forward horizontal distance from the cockpit of an aircraft in flight at which prominent unlighted objects may be seen and identified by day, and prominent lighted objects may be seen and identified by night. As such, the required flight visibility is met if at approach minimums (MDA, DA, DH) and the approach lights are in sight.

The following reference is from FAR 121.651, takeoff and landing minimums:

On the Final Approach Segment (FAS), if the weather report indicates below-minimum conditions, the approach may continue to DA/DH or MDA. Upon reaching DA/DH or at MDA, and at any time before the missed approach point, the pilot may continue the approach below DA/DH or MDA if the following requirements are met:

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and where that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach procedure being used;

(3) Except for Category II or Category III approaches where any necessary visual reference requirements are specified by authorization of the Administrator, at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot:

(i) The approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable.

(ii) The threshold.

(iii) The threshold markings.

(iv) The threshold lights.

(v) The runway end identifier lights.

(vi) The visual approach slope indicator.

(vii) The touchdown zone or touchdown zone markings.

(viii) The touchdown zone lights.

(ix) The runway or runway markings.

(x) The runway lights;

I know that is typical FAA legal language, but to summarize, to descend out of the MDA/DA/DH, you must have white lights (approach light system) in sight. To descend below 100' TDZE, you must see colored lights or concrete.