Airfield Circles

Greetings!

This week I received APM Mission Planner compatible Hardware and while doing the first steps of setting it up I noticed the local Park I keep frequenting being overlaid by an Airfield Circle[color=#FF0000]:[/color]

My House, not shown but somewhere near the top left, is also inside the Circle.

What exactly does this Circle do or what does it prevent me from doing?[color=#FF0000]:[/color]
a) Does it only serve as a warning?
b) Does it prevent me from doing a Mission inside the area?
c) Does it even prevent me from flying manually inside the area when not using the Mission Planner?

It should not prevent you from planning a mission inside the airfield area or loading the mission into the uav and executing it. It also does not prevent manual operation of the uav inside the area.

Thanks for clearing this up =)