Boeing 747 Horn
Does an airplane have a horn?
We checked the horn of a Boeing 747 and the anwser is YES!
Based in the nose wheel it is operated from the cockpit (press "P" and "1").
It's installed as a warning signal for groundcrew and it is not not very impressive. Therfore we urge Boeing to use Hadley horns in stead.
We can imagine some of you want to have this horn. You can order it with the airplane attached to it. Please note that it will take some time to process your order and we only guarantee that the horn works... In fact: we think you are better off just contacting the Boeing company:
http://www.boeing.com/commercial/747/#/fun-facts