Hi Benjamin – I booked an Antarctica cruise departing in December and have the same question. It looks like there are regular flights daily between Buenos Aires and Ushuaia. I’m traveling from the East Coast, probably will fly Canadian Airlines through Toronto to BA, stay a day, then hop down on a separate booking to Ushuaia. I’ll keep you posted as I learn more.
I’m a solo traveler. I embark in mid-December!
I am also plaaning for December
Most flights to Ushuaia leave from AEP, the local airport in Buenos Aires. I've always flown in to EZE (the international airport) overnighted, or a few days in Buenos Aires and then gone to AEP for the flight south. Some flights out of Ushuaia do land at EZE and you can get right to your homeward international flight.
You can check flights via PTY (panama) or SCL (Santiago, Chile) which might offer different options.
Brenda - when are you heading down? We are leaving (east coast) on the 17th of December. We're heading out for a 22 day excursion through Quark