In reply to CLEAR PROP's original question, it is indeed as some others have mentioned, i.e. Heavy aircraft from foreign operators are issued an instrument approach unless they specifically request a visual.
AIP refers:
ENR (2 SEP 04)
11.5.2 In addition to the requirements of para 11.5.1, with the exception of
Australian and New Zealand operators and aircraft conducting independent visual approaches at Sydney, HEAVY jet aircraft will
only be assigned a visual approach when:
a. specifically requested by the pilot, and the pilot has reported
the landing runway in sight; or
b. the straight-in approach aid is unserviceable.