Rumour
has it that..............
APU was started as aircraft was being towed back (heading north) on its path to Bay 10,
Prevailing wind was from the north, and when aircraft was turn in from DOM 1/TWY C the northerly blew the smoke from the superheated hydraulic oil back up the pipe into the pax cabin.
Captain called Mayday Mayday Mayday on Sydney Ground East 121.7 and deployed the emergency slides.
You would have to safely assume he was pre-empting a possible fire. Best and only call any trained professional would make in those circumstances.
So bingo, from Local Standby to Full emergency in a hearbeat, 100/100 to all those involved, possible disaster averted and as it turned out, it became just another news item on the 6 o'clock News.
For anyone who believes that pilots are overpaid please go away and have a good think about that........