Tip: Are you a non-native English speaker? I have just finished creating a 
Web AppWe know it from films: The main hero is dying in his friend’s arms, saying his last words. Then his eyes close, and the friend says, with tears in his eyes, “He is gone.” In a novel, when a lover leaves her partner, he may say, “She is gone, and she is not coming back.”
Such usage is idiomatic and is not really an instance of a general grammatical rule. A non-native speaker just has to remember that
to be gone = to be far away; to have disappeared; (figuratively) to be dead
The form “have gone”, on the other hand, is the ordinary past perfect of “to go” and can be used just like any other verb:
Where is Peter? He has gone to France.
Has he gone mad?
Has he gone mad?
