Hi, relative newbie here. I was trained that my primary focus in checking airspace when getting ready to deploy was down, left and right. My major responsibility is to make sure the space "below" me was clear, and to expect that the people above me are doing the same. Yes, I know I am ultimately responsible for myself, and I can see that knowing I'm clear in ALL directions is preferred, but I wonder about the practicalities of "barrel rolling" to clear the airspace above you. Don't you lose some of your focus downward if you have to barrel roll to clear upward? Do you really have sufficient time and altitude to alter your path if in fact you DO see someone above you? And if you do vector to avoid someone above you, don't you run the risk of moving into someone else's airspace, maybe someone you hadn't seen previously? Just wondering. larry