 In the aftermath of the Ghost Flight, the Civil Aviation Safety Authority issued a Discussion Paper and a Notice of Proposed Rule Making (NPRM), both proposing aural warning in the Beechcraft Super King Air and other pressurised aircraft.The outcome of consultation on the NPRM was that the Civil Aviation Safety Authority did not mandate aural warning of inadequate cabin pressure and this angered the families of some of the victims.Instead, the Civil Aviation Safety Authority issued a notice to owners of pressurised aircraft registered in Australia recommending installation of an aural warning, but not making it mandatory.