Zagreb ZAG to Sofia SOF flight with Air Serbia

Air Serbia is the national flag carrier of Serbia, with its main hub at Belgrade Nikola Tesla Airport. The airline's origins trace back to Aeroput, established in 1927, making it one of the oldest airlines in Europe. Rebranded as Air Serbia in 2013 after a partnership with Etihad Airways, the airline has since modernized its fleet and expanded its network. Air Serbia operates scheduled, seasonal, and charter flights to over 90 destinations across Europe, the Mediterranean, North America, Asia, and Africa. They offer both passenger and cargo services, and in cooperation with partner airlines, extend their reach to international destinations in Asia, Australia, North America, and Africa. The airline is a member of the International Air Transport Association (IATA).

Buzz is a Polish airline, a subsidiary of Ryanair Holdings, headquartered in Warsaw. It operates scheduled flights on behalf of Ryanair and also offers its own charter flights from bases in Poland, Czechia, and Bulgaria. Originally launched by KLM in 1999 as a low-cost carrier, it was acquired by Ryanair in 2003 and ceased operations in 2004. The Buzz name was revived in 2019 when Ryanair rebranded its Polish charter airline, Ryanair Sun, to Buzz. Buzz operates a fleet primarily consisting of Boeing 737 aircraft.