From todays West Australian
Battle on over airport alternative
“For us, Cunderdin makes far more sense because it’s so close to Perth and gives us the opportunity of returning to Perth before our crew are over their duty time hours and that is critical.”
It would seem that the crew duty time + diversion (67nm) & subsequent required extension (no obvious pressure to extend) is right on the margin of the anticipated CASA Flight & Duty time exception.
h/t to Capt Bloogs, on the other thread
post #39 Cunderdin Ticks All YPPH alternate boxes
Great Circle Mapper