The HFESA has two international conferences organised every year - OZCHI and the HFESA Conference.
OZCHI - This is the annual conference organised by CHISIG (the Computer-Human Interaction Special Interest Group of the HFESA). This conference has recently surpassed its 20 year anniversary which is certainly a milestone! This conference focuses on Computer-Human Interaction topics, and future uses of technologies.
HFESA Conference - This is the annual conference organised by the HFESA. This conference has a broad focus and may cover any issue pertinent to Human Factors and / or Ergonomics. For information about the HFESA 2011 Conference: http://www.ergonomics.org.au/home_page_module/home_right_panel/pages/hfesaannualconf2011.aspx