Comment by zombees

In general aviation (anything other than the airlines for our purposes) midair collisions happen with alarming regularity anywhere there is any congregation of aircraft (typically within 10mi of a non-towered airport). Add to this that they are nearly 100% fatal, unlike traffic collisions, and you have a recipe for disaster. There are systems coming online to help mitigate this issue (ADS-B) but they've been in the pipeline for years and won't see universal adoption until 2020 in theory.