Iron
I'm not totally comfortable with emulating the popular press, but Australia's worst is usually quoted as Hudson VH-ALA which crashed in the Territory of Papua New Guinea (pre independence) on 18 April 1948 killing all 37 on board. The following is a precis from Jim Sinclair's book "Balus":
VH-ALA crashed on take-off from Lae for Bulolo killing all on board. The pilot, Stanley Bowern, lost control when an engine failed on take-off. The aircraft crashed and burned on an island in the Markham River. In addition to the pilot, the aircraft was carrying 33 native labourers and 3 Guinea Air Traders engineers. Only the pilot was provided with a seat or seat belt. This accident prompted legislation that required all passengers, regardless of race, be provided with a seat and a seat belt. As the aeroplane was not overloaded, no charges were brought against Guinea Air Traders.