In response to the 11 September incidents , the Commonwealth instituted an Air Security Officer ( ASO ) Program under the APS . These employees were generally referred to in the media as Sky Marshals . The ASO Programme provided a discreet anti-hijacking capability for Australian civil aviation by providing armed security personnel on board aircraft . This involves both random and intelligence-led placement of armed ASOs on flights operated by Australian registered air carriers , including domestic and international flights into and out of Australia
11 September incidents
September 11 attacks
Australian Protective Service