Why did both crew consider YMIA, have a look at the flight plan tracks for each aircaft. They both flew past YMIA on the way to YPAD and at the times they flew past YMIA was clear.
From the report, the YMIA 2230Z METAR (before the flew past) had BKN034. The AWIS was U/S so unless they requested YMIA weather when flying past from ATC and ignored the TEMPO on the TAF, it's hard to say it was clear.
Just reading the appendix again - VYK had calculated and advised a diversion point for YMML and at that time, YPAD had a SPECI and an ATIS which were below the landing minima but a TTF that said they were fine to continue. And at 2302 new TAFs for YPAD and YMIA (admittedly for the 0000 commencement) also indicated visual conditions. They were completely screwed by the BOM.
4Dogs:
The system must work for all aircraft and should never depend on what an ops centre may or may not be doing
Airline's aren't my world but from the recent thread here, I understood that Ops Control was required for the airlines to provide the service that Flightwatch used to. Yes, it would seem that being SATCOM, VHF and ACARS equipped that the crew of YIR had no excuse for not knowing the amended Adelaide TAF but the statements by the ops centre that they knew about the changed conditions but didn't pass it on (as they have a meterologist and access to the full weather briefing including the 'code grey' information), combined with the fact they didn't seem to know where the plane was (thought it was on descent at 2220)
I also knew that any TTF is only valid until it is replaced (ie, generally good for 30 minutes but sometimes less!)
But by it's nature, any changes shouldn't be of a 'gotcha' nature. How can it be possible to issue a TAF AMD saying PROB30 1721/1724 0500 FG and at the same time (2100Z) issue a TTF saying NOSIG which was valid from 2100 to 2400. It beggars belief as it only captured those arriving post TTF and within the buffer zone as needing a alternate/holding.