Accessing a non-class variable from inside a class defined in ActionScript

In my main timeline, I’ve got a multidimensional array variable named “map”.
On frame 1, this “map” variable is filled up with instances of a class named “maparea” (defined in an external actionscript file), but now I’d like to add a function named “neighbourcheck” in the “maparea” class, which will go through it’s neighbours on the map and check some properties on them.

But how can I access the main timeline variable “map” from inside my “maparea” class?

I’ve tried to use “_global.map” but that left me with the error “1120: Access of undefined property _global.”