To make this template more effective, I have made the following changes:
Converted style of template so it can be edited from the template on any page on which it is located
'Associated airlines' (which was linked to subsidiary), has been renamed to 'Subsidiaries' and only those airlines which fulfill the definition of a subsidiary are listed. The term 'associated' implies that Avianca has a shareholding in the companies which were listed (Ocean Air, VIP and Capital Airlines), and it is not a shareholder, they all share common ownership.
'Defuncted airlines' has been changed to simply 'History'; 'defuncted airlines' is not proper English. WayraPeru has been removed, as it was not an entity which preceded Avianca, nor was it a subsidiary
'Related companies' has been reduced to a single link and renamed to 'Parent company'; the other 2 wikilinks in this section all redirected to the link which remains anyway.
The website URL has been removed. Navbox templates are meant for easy navigation of directly related articles on WP, not as a promotional tool for an entity, and most certainly not for external links.