Originally Posted by
usedtobeATC
DOC 4444.
7.15.3 Approach lighting.
Note.— Approach lighting includes such lights as simple approach lighting systems, precision approach lighting systems, visual approach slope indicator systems, circling guidance lights, approach light beacons and runway alignment indicators.
A `Precision Approach Lighting System`, which I believe can be to CAT 1,2 or 3 standards, is something completely different to the PAPIs (Precision Approach Path Indicator) as far as I am aware.
Having done a bit more digging, ICAO Annex 14 does indeed class both PAPI and VASI as "Visual Approach Slope Indicator Systems", but if my interpretation of the relevant chapter is correct, they are not formally part of Approach Lighting.
I therefore tend to agree with those who suggest that PAPI is not part of an `ALS`. Is it, in fact, solely intended as a visual approach aid and therefore would not affect instrument approach RVR minima if it were to be inoperative?
Further opinions on this would be gratefully received!!
