Function XPLMGetNextNavAid 

pub unsafe extern "C" fn XPLMGetNextNavAid(
    inNavAidRef: XPLMNavRef,
) -> XPLMNavRef

XPLMGetNextNavAid

Given a valid navaid ref, this routine returns the next navaid. It returns XPLM_NAV_NOT_FOUND if the navaid passed in was invalid or if the navaid passed in was the last one in the database. Use this routine to iterate across all like-typed navaids or the entire database.