Firstly, it is illegal to fly within 30m of a building, vehicles, boats or people -
https://www.casa.gov.au/sites/g/files/net351/f/_assets/main/lib100071/flying_with_control_model.pdf.
If one is flying around, a hose, net, string, fishing line, etc... can be used to knock it down. Basically anything that will get tangled in the props will bring it down. I've seen one taken down by someone throwing a t-shirt at it which caught a prop. Once you have it in your possession, secure it and call the
. When the person comes looking for it, send them to the
station.
Having said that, it should be flown within line of sight, so the operator would need to be around. They could be flying it by FPV, so hiding around the corner somewhere.
Generally, if they see you getting close to knocking it down, chances are they will move on and leave you alone. They won't want to risk losing their drone to you.
I have a couple of drones/tri-copter and I make sure to never let it out of my yard. It's always more fun and safer to fly it in a registered model aircraft flying area anyway.
Cheers
whitedg