VTOLs are Ground Units, and cannot have an Altitude; they can never use the Low Altitude Table. Note that Altitude and Elevation are two significantly different concepts.
VTOLs do not have a maximum Elevation they can achieve. We will request errata to place their ceiling at 500 levels.
I'm not completely sure what the "+1 regardless high in low altitude" refers to. If that's still something you want to ask, please rephrase and post in this thread.