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I was looking at airplanes a while back and noticed that there is sometimes a wire running from about the CG near the wind to about halfway up the tail. I see this more on 737s but I have also seen it on C130s. What is this wire? To hold up the tail? I have seen: What is this wire going from mid-fuselage to the tail on this 737? but I am more interested in all of the other planes that have it too. Are there planes that actually use guy-wires for support or are all of the wires I see antennas?