A NOTE ON TIME ZONES IN SOUTH AMERICA
Quito is on the same time right now as EST.
Santiago and all of Chile, including PUNTA ARENAS, is on Daylight Time right now, with the net effect that they are 2 hours ahead of EST.
Ushuaia, Buenos Aires and all of Argentina is on standard time, 2 hours ahead of EST.
Brazil, relevant to AR11 only for Sao Paulo airport, is on Daylight time right now, with the net effect that it is 3 hours ahead of EST.
So, for the flights from USHUAIA, the first one to Buenos Aires will involve no time change, the second one from there to Sao Paulo will involve moving the clock one hour ahead, and then from Sao Paulo to Johannesburg(7 hours ahead of EST) the clock will have to be moved ahead another 4 hours. There is no time difference between Johannesburg and Maputo.