What are all those choppers doing in my back yard?

Seriously, about 30 big black helicopters have flown over my house in the last half hour. And they’re still coming (sporadically)

I search in the news, and Google, but I’m not seein nuthin.

The Internets have failed me! I turn to dopers. What on earth could be going on?

From The Age (13 March): link

It looks like it’s been happening around Melbourne for the past few days, and continues until tomorrow.

yep, that would be it!

It’s taken them a while to get round to the inner city then. Maybe it’s too easy to need practising…