Originally Posted by
deniah
More perplexing is after clearing C&I I was not allowed to re-check in onto the GRU-GIG segment. Had to get transferred onto local TAM flight. FTers told me my original itinerary (booked through agency) was technically not legal
UA does not have authority to fly a domestic segment in Brazil... same as the fact that TAM can't pick up passengers in NY and take them to Chicago.
If the itinerary is all UA (or CO or AA, for that matter) and is USA to Rio via Sao Paulo, then I&C are done in Rio. If you transfer from UA to a Brazilian carrier (TAM or Gol) for the segment from Sao Paulo to Rio, then you go through customs in Sao Paulo.