| visual glide slope indicator | indicateur visuel d’alignement de descente (There are four basic types of visual glide slope indicators that are used in Canada: visual approach slope indicator (VASI), abbreviated visual approach slope indicator (AVASI), precision approach path indicator (PAPI), and abbreviated precision approach path indicator (APAPI). The PAPI and APAPI are the present standard. ICAO uses the term VASIS for VGSI. Other systems, such as the T visual approach slope indicator system (T-VASIS) and the abbreviated T visual approach slope indicator system (AT-VASIS) used by ICAO and some Australian and Pacific Islands airports, are expected to be progressively phased out of service) |