Quote:
In some countries a PAPI or VASIS may be seen on base leg but obstacle clearance not guaranteed until within plus or minus 15 degrees either side of extended runway centre-line. Short answer: Don't descend until on final.
See above. That statement is simply not correct.
From AIP Australia:
Note 1. T-VASIS. The night azimuth splay is normally increased to 30 degrees to permit T-VASIS to be visible on base leg. However, obstacle clearance is not guaranteed until the aircraft is within the approach obstacle clearance surface. Accordingly, T-VASIS should not be used for approach slope guidance until the aircraft is aligned with the runway.