In the US see and avoid is the rule once airborn. It works really well. It works at all altitudes from lift off to cruise. Electronic help came just recently but it shouldn't be your collision avoidance system. Looking out the window and doing what makes sense is the best way to avoid a midair. Electronics will not avoid conflict more than your eyeball. Most of the near miss reports recently would be solved by looking out the window. Quite a simple concept but so accurate. Remember constant bearing, decreasing range and how that can ruin your day? Change the constant bearing and all will be fine. Usually turning behind the conflict fixes everything. I went through a long career of flying using this technique and believe looking out the window is the best way to retire with no incidents. It worked well for me.