Takeoffs and landings.

[Tim B]

I was at Botany Bay on Sunday, around 1pm when I noticed an unusual occurrence regarding takeoff and landing directions.
The inbound flights were landing on runway 34L, after coming in over Botany Bay. There were also planes taking off on the third runway, 16L, also over Botany Bay, and banking left shortly after takeoff to ensure a good distance from the incoming flights on the main runway.
There were calm wind conditions at the time, so it wouldn't be a problem for the planes, but I have never seen this happen before.
Has anybody else ever witnessed this?