Colombia is well connected by air to major cities in South and Central America, as well as a number of major destinations in the US, Canada and Europe.
Colombia's biggest international airport is Bogotá's newly renovated Aeropuerto Internacional El Dorado. A second phase of its expansion project is under way.
Other major airports servicing international flights:
Aeropuerto Internacional José María Córdova Serving Medellín.
Aeropuerto Internacional Rafael Núñez In Cartagena.
Aeropuerto Alfonso Bonilla Aragón Serving Cali.
Colombia's national carrier is Avianca, which is one of the better airlines in the region both in terms of service and reliability.
Colombia requires, technically at least, that visitors have an onward ticket before they're allowed into the country. Airlines and travel agents quite strictly enforce this, and no one will sell you a one-way ticket unless you already have an onward ticket. Upon arrival in Colombia, however, hardly any immigration officials will ask you to present your onward ticket.
The trick is to buy a fully refundable ticket with your credit card and request a refund upon arrival in Colombia. If arriving overland, a printout of an unpaid reservation may also be sufficient to get past the border guards. Scruffy-looking travelers are more likely to be asked to show an onward ticket than those who are neatly attired.
There is a COP$115,200 or US$38 departure tax on international flights. While previously it was paid at a separate window, it's now generally included in the price of the ticket.
In theory travelers visiting Colombia for less than 60 days are exempt from this charge; round-trip tickets for less than this period originating outside Colombia should not have the tax included.
Airline tickets in South America are often expensive. If you are traveling one way to Ecuador, Venezuela or Brazil, you will probably find it cheaper to fly domestically to the land border (Ipiales, Cúcuta or Leticia, respectively), cross the land border and take another domestic flight to your final destination.
That said, Bogotá is often the cheapest entry point to South America and there are plenty of intercontinental flights out of Bogotá, plus a few out of Cali and Medellín. You can fly Bogotá–Quito and Cali–Quito, for example. As a result of the political crisis in Venezuela, which has seen Avianca suspend service to that country, seats in and out of Caracas are very difficult to come by.