Perhaps someone with access to the then met report could confirm or eliminate any possibility of carb icing for a start?
Well, the data from the FlightRadar screen shot above shows a date/time of 18 November, 2341 UTC.
METAR YSSY 182330Z 02012KT 9999 FEW030 21/12 Q1010=
METAR YSSY 182300Z 02007KT 350V070 9999 SCT030 20/11 Q1011=
