Salgado Filho International Airport (POA) is the international airport of Porto Alegre, located 7 km (4.3 miles) far from downtown. There are regular daily flights linking Porto Alegre to the majority of Brazilian state capitals, as well direct flights from/to Argentina, Uruguay, Peru, Panama, USA, and Portugal. The airport is served by all major Brazilian airlines, such as Azul, Gol, Varig, TAM, and international ones, like American Airlines, TAP, COPA, and Aerolineas Argentinas. Several flights from/to the biggest cities of Brazil are available daily in many different scheduled times, so it is easy to get to Porto Alegre arriving in São Paulo or Rio de Janeiro and taking a flight from there, buying the whole trip including the connection (whole trip tickets are cheaper than buying each flight separately or at arrival's time).
Bus trips form São Paulo and Rio de Janeiro to Porto Alegre are also daily offered but, as Brazil has continental dimensions, they are quite long (for instance, up to 20 hours from São Paulo to Porto Alegre).
When you arrive at Porto Alegre's airport, you can choose to pick up a taxi to go directly to your hotel (easier), or get a bus or train to downtown. There are two types of taxis at the airport. The red ones are the usual taxis you find around the city. The white taxis serve only the airport. Both charge the same price, counted by meter.
The airport facility has restaurants and shops. Be aware that Azul Linhas Aéreas operates only in Terminal 2, that is a different building connected by a free shuttle service every 15 minutes.
