SharePoint hosted app, accessing the lists of the ParentWeb

I have a SharePoint 2013 hosted app which is trying to access the lists of the parent web.  This is the code I am using and when I try this I get an access denied error.  How do I fix this? The line in bold throws the error.

 var web = this.context.get_site().openWebById(this.webInfo.get_id());
    collList = web.get_lists();
    context.load(collList);