Think of the GTX 330 as an excellent, albeit expensive ($5000) transponder that provides anti-collision capability as a cheap add on.

By Paul Bertorelli

Although we're not sure they should, some pilots worry about the risk of mid-air collision to the point of obsession. The threat seemingly looms large but, in reality, mid-airs are so far down the list of things that can kill you in an airplane that the numbers are sometimes too small to measure accurately. …