tubby:
Aterpster, what criteria would the originator of the LOC procedure have used to decide that it was not to be used at night and then a few years later change this policy?
Penetrations of the visual segment's 20:1 surface. Later, the PAPI was determined to be accurate, thus (as is done on a case-by-case basis) the PAPI, when operating, was determined to be mitigating.