The DC-9 struck approach lights 1600 feet short of the runway while on an ILS approach to runway 20. The aircraft continued, struck dyke 785 feet short of the threshold and skidded for another 1200 feet before coming to rest 250 feet left of the runway centerline. PROBABLE CAUSE: “The pilot did not recognize the need to correct an excessive rate of descent after the aircraft had passed decision height. This occurred despite two verbal reports of increasing sink rate by the first officer. The captain disregarded the reports by the first officer, possibly because of the influence of a visual illusion caused by the refraction of light through the heavy rain on the windshield. The excessive rate of descent was initiated by a wind shear condition which extended in the lower levels of the approach path and a glide slope that tended toward the lower signal limit.”