NEWS FLASH
Air Serbia will increase frequencies on flights between Belgrade and Tianjin from one to two weekly. Starting October 31, services between the Serbian capital and the Chinese city will run each Tuesday and Saturday, pending government approval. The return flight will operate on Wednesdays and Sundays, meaning the aircraft will no longer spend over 24 hours in Tianjin, as is currently the case, rather, the Airbus A330-200 jet will have a 2-hour 50-minute turnaround time. Air Serbia has previously said it plans to increase operations to China, with flights to Shanghai and Guangzhou expected to be added sometime over the coming winter.

Comments
Air Serbia has none of those problems - not even pending government approval for twice weekly YYZ flights, unlike TSN.
That leaves Toronto as Belgrade's busiest unserved destination in the world by far. Ask Air Serbia why are they still holding back on announcing next North American destination?
They are trying to bring in more cheap labor from India and Pakistan to fix the problem, however system there is too corrupted by their government and JU is well aware of the situation .
If those arguments were valid Air Serbia should have expanded only to China instead of launching Chicago, also home to price sensitive diaspora. That diaspora is filling business class on Chicago flights and same is expected for Toronto.