The most convenient way to reach Goiânia is to arrive at São Paulo airport (Guarulhos International Airport, GRU https://www.gru.com.br/en) or at Brasília International Airport, BSB (https://www.bsb.aero/en).
From Europe: Flight time from Europe to Sao Paulo is just over 11 hours and to Brasilia is 10 to 16 hours, depending on your starting point. Most flights leave from Europe in the evening and arrive Brazil early in the morning. On the return leg they leave late afternoon or early evening to get to Europe the following day around lunchtime or earlier.
Air France, Alitalia, British Airways, Iberia, KLM, Lufthansa, Swiss, TAM and TAP all run regular services between Europe and Brazil. This means that travelers have a choice of several different airlines linking the two continents daily.
From the US: Flights by American Airlines, Continental, Delta, United and the Brazilian flag carrier LATAM link the US with Brazil. Flight time is 8.5 hours from Miami to São Paulo, just over 9 hours from New York, 11 hours from Atlanta, 13 hours from Los Angeles and 16 hours from San Francisco. Concerning the flights between the USA and Brasilia, the average time is 9 to 13 hours, depending on the place of departure. Most flights between North America and Brazil are overnight flights that arrive Brazil in the early morning.
From Central and South America: There are flights from all the Central and South American capitals to Sao Paulo and Brasilia.
Since other countries not included in the descriptions, please consult the international airports in their countries.