Lots of good information in the quoted post, but a comment on this point: Many cruise itineraries start and end in Buenos Aires, with flights to/from Ushuaia and perhaps a tour of BA included. (I assume it would be the same on the Chilean side, but, despite five trips to Chile, I've never gone to Antarctica from there.) If that's the case, allowing the extra day may still be a good idea - I always do, since the only time you have a travel delay is when you don't - but the considerations are much the same as for any trip to any major international airport anywhere. If there's an issue with internal flights within Argentina (or Chile), it's the cruise line's problem. If they have to hold the ship, they'll hold it. They often build a visit to Ushuaia National Park or something else into the itinerary to provide some flexibility. If internal flights are delayed by a few hours, they cancel that visit and sail on schedule.