Use external libraries for your purposes, like this one.
Here is described, how to use it (you can find there also other useful informations).
import com.coreyoneil.collision.CollisionList;
var myCollisionList:CollisionList = new CollisionList(hero);
//add all stages separately
myCollisionList.addItem(stage[1...n]);
if(myCollisionList.checkCollisions().length > 0) {
//colision detected
}