Summer officially starts later this week. And this is when airlines are finalizing their winter schedules, especially for long-haul flying. The major unresolved issued from Charlotte — we know the European flying this winter though the answer is a step backward — is whether US Airways has obtained the necessary permissions to start service to Sao Paulo, Brazil.

Sao Paulo (GRU) is the largest market in South America. And though US Airways already has the route authority to fly to the city, that doesn’t do it much good if it can’t get landing and takeoff slots in GRU at reasonable times or a parking space for the plane to sit during its long (12 hour plus) layover in Sao Paulo (business travelers want to fly overnight between the United States and Brazil).

Sao Paulo landing slots are assigned every six months. So if US Airways got slots it can use for a CLT-GRU flight starting in November or December, we should hear about soon. And if we hear nothing, then the flight won’t happen until May 2013 at the earliest.