It will be reported to the Australian Transaction Reports and Analysis Centre (AUSTRAC), but this won't prevent you from flying, assuming the money was earned legally and you aren't doing anything illegal with the withdrawal.
Under current Federal legislation, all Australian banks are required
to report cash transactions of $10,000 or more (or foreign
equivalent), including details of the relevant account holders, to the
regulator, the Australian Transaction Reports and Analysis Centre
(AUSTRAC). From 1 October 2011, new rules are introduced that require
banks to collect information, record and report on the identity of
anyone performing a cash transaction of $10,000 or more to AUSTRAC.
Also, depending on the size of the bank, you may have to call ahead to make sure that they have enough cash onhand.