Airplanes differ. Not all of them have that closet up front.

If I were flying and wanted to take a guitar, I would take a small one and carry it on. Put bubble pack or foam in the case to protect it from bumps and bangs.

Guitars, etc, are surprisingly top heavy. (End with pegs is heavy.) Don't stand the case up.

Security personnel don't like the sight of tubes. When I send my flutes and recorders through the X-ray, I catch somebody's eye, smile, and say, "This bag has flutes in it."