Paragraph 495 of FAA Order 8400.10, Air Transportation Operations Inspector's Handbook:
“The following is a list of statements which describe what RVR is not:
(a) RVR is not a measure of meteorological visibility.
(b) RVR is not a measure of surface visibility or tower visibility.
(c) RVR is not a measure of seeing conditions on taxiways, ramps, or aprons.
(d) RVR is not a measure of seeing conditions at or near MDA or DH.
(e) In the U.S., RVR is not measured or reported by a human observer.
(f) RVR IS NOT ‘VISIBILITY.’ "
The Pilot/Controller Glossary defines flight visibility:
“Flight Visibility - 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.”
AC 120-29A
4.3.4.4. “Specified Visual Reference” Requirements for Category I or Category II.
a. Section 91.175 and Standard OpSpecs specify that for operation below the DA(H) or MDA(H) on an
instrument approach, the required visual reference to continue the approach must be established. Unless otherwise authorized by the CMO (e.g., POI or APM for a particular type) the required visual reference may be considered to
be those provisions as listed in section 91.175 items (c) and (d).
b. Circumstances in which the operator may request and the CMO may authorize use of alternative visual
reference provisions might be situations such as certain Category I and II minima are based on use of autoland or
HUD (see paragraph 10.5.3). In this instance provisions such as those shown in section 91.175 (c) (3) (i) for “red
terminating bars” or “red side row bars” may not be necessary or appropriate. This is because these particular
approach lighting visual references or configurations may not always be needed when operations are predicated on
HUD or autoland use. They may not even be installed or applicable as a part of the approach lighting system for the
runway or runways to be specially authorized. Conversely, for operations such as the ones noted above for autoland
or HUD, it may be determined by the operator and CMO that continued descent below the DA(H) based solely on
visual contact with a VGSI (which may in instances be otherwise permitted by 14 CFR), but without having sight of
either the runway, runway lights, touchdown zone lights, centerline lights, or runway markings would not be
appropriate. In this instance, the CMO may authorize the operator to define and use alternate visual references or
visual reference combinations for Category I and II operations, rather than relying solely on the sighting of a VGSI
as a basis for continued descent below a DA(H).
§ 91.175 Takeoff and landing under IFR.
(c) Operation below DA/ DH or MDA. Except as provided in paragraph (l) of this section, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless—
(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 for operations conducted under part 121 or part 135 unless 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 being used; and
(3) Except for a Category II or Category III approach where any necessary visual reference requirements are specified by 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.
(d) Landing. No pilot operating an aircraft, except a military aircraft of the United States, may land that aircraft when—
(1) For operations conducted under paragraph (l) of this section, the requirements of (l)(4) of this section are not met; or
(2) For all other part 91 operations and parts 121, 125, 129, and 135 operations, the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used.
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From the references above, flight visibility is not approach visibility. On approaches with a DA/DH, where a decision is being made, once established on the final segment, the approach may be continued even when the reported WX vis is below the published approach mins. Once at DA/DH(or MDA), as long as any approach lights are in sight the approach may continue. At 100' the lighting listed in 91.175 (c) must be in sight.
As a rule we would teach, at MDA/DA any lights, at 100' must see colored lights to continue.