"...or could I push it to putting up a note on the board at my local supermarket or backpacker's?"
CIVIL AVIATION REGULATIONS 1988 - REG 210
Restriction of advertising of commercial operations
(1) A person must not give a public notice, by newspaper advertisement, broadcast statement or any other means of public announcement, to the effect that a person is willing to undertake by use of an Australian aircraft any commercial operations if the last mentioned person has not obtained an Air Operator's Certificate authorising the conduct of those operations.
Penalty: 10 penalty units.
(2) An offence against subregulation (1) is an offence of strict liability.
Note For strict liability , see section 6.1 of the Criminal Code .
Which part of CAR210 do you not understand?
