Sliač Airport (IATA: SLD, ICAO: LZSL), historically Letisko Tri Duby (literally "The Three Oaks Airport") - is an international airport in central Slovakia, between Zvolen and Banská Bystrica, near the spa town of Sliač. The airport has one runway, which is 2,400 m long (18/36). The airport is shared between military and civilian use.
The Tri Duby Airport played an important role during the Slovak National Uprising in 1944, when it became the most important airport of the anti-Nazi Resistance. Between 6 September and 25 October 1944, the airport was the main base of the Slovak Insurgent Air Force, but it had to be evacuated afterwards because of the advancing German forces. Since the territory controlled by the rebels was encircled by the hostile German forces, Tri Duby and the nearby Zolná airport were the main gateways to the rest of the world. In addition to the significant Soviet aid, the United States sent supplies and OSS operatives through Tri Duby and these flights also evacuated American fliers liberated from German POW camps.
The airport changed its name from Tri Duby to Sliač in 1945. In 2009, it was closed for a major reconstruction project financed in part by NATO and EU. It was reopened in May 2011 for military and June 2011 for civilian use. Charter flights are currently operated to Bourgas and Antalya. Others are planned.