Most international flights use the former Otopeni Airport, now renamed Henri Coanda Airport, which is located around 10 miles to the north of the city, and the Romanian national airline is Tarom. The major international airlines (BA, KLM, etc) use this airport, whereas budget airline Wizzair use Baneasa Airport, which is actually around 5 miles closer to the city.
Buses from the airports run every 15 minutes during the day (every half hour at weekends) and tickets are cheap at only €1 for a return. Tickets are to be bought before boarding and validated on board.
The journey time is around 40 minutes from Henri Coanda, and around 20 minutes from Baneasa to the city centre.
Taxis to town cost around €15 and €7 from the two airports respectively.
By Bus
Eurolines run services to Bucharest from various European cities (such as Paris, Berlin and Rome) - with prices ranging from around €60 to €120 depending on destination. For more details check out their website.
