PSO program and its application in Croatia
The Republic of Croatia implements a multi-year PSO (Public Service Obligation) program in which it undertakes to connect remote regions within the Republic of Croatia by air.
In the simplest way, this program enables countries within the EU to co-finance airlines, which almost all member states do, noting that most PSO tenders in countries are awarded to their national airlines.
Preservation of transport connections in domestic scheduled air transport is of importance for the economic and social development of the Republic of Croatia because it brings a number of direct, indirect, induced and catalytic benefits to the society. The obligation to perform domestic flights is imposed only up to the minimum necessary measures that meet the criteria of connectivity, regularity, capacity and affordability, and without which airlines would not have a commercial interest.

Therefore, the PSO tender serves to operate scheduled air services on routes within the Republic of Croatia on which airlines would not otherwise operate, given that they would not have a commercial interest.
As part of PSO tender, Croatia Airlines operates on the following routes:
Zagreb - Split - Zagreb,
Zagreb - Dubrovnik - Zagreb,
Zagreb - Zadar - Pula - Zadar - Zagreb,
Zadar - Brac - Zagreb,
Osijek - Split - Osijek,
Osijek - Dubrovnik - Osijek.
Private airline from Croatia, Trade Air, operates on the following routes:
Osijek - Zagreb - Osijek,
Osijek - Pula - Osijek,
Osijek - Rijeka - Osijek,
Pula - Split - Pula,
Rijeka - Split - Dubrovnik - Split - Rijeka.
These routes will operate until the end of October 2020, when a new four-year period will begin in which the Osijek - Rijeka - Osijek route will be abolished, but therefore routes from Osijek to Zadar and from Rijeka to Zadar will be introduced.
What is interesting, on the routes operated by Trade Air, there is a very small aircraft, with the capacity of only 19 passengers. Tickets for Trade Air routes can be purchased on their website, as well as on various search engines and at Croatia Airlines website.
From all these routes it can be concluded that those have a common purpose, to connect the most remote parts of Croatia, or on the other hand, to enable a direct flight to Zagreb where passengers can continue their journey to destinations in Europe and the world.
The example on the Osijek - Rijeka - Osijek route
If you have to travel from Rijeka to Osijek this Tuesday, June 30, the bus trip will take almost 7 hours and you will have to pay a minimum of 280 kuna for a one-way ticket.
If you decide to travel by train, you will travel from Rijeka to Osijek for over 9 hours for approximately 230 kunas.
The trip from Rijeka to Osijek by car would take almost 4 hours, with a cost of at least 200 kunas for fuel and 188 kunas toll in one direction only.
But there is an option and by plane. The trip will take only 40 minutes, and for a one-way ticket you need to pay approximately 355 kuna.
From Rijeka to Dubrovnik by plane
The journey by bus from Rijeka to Dubrovnik takes over 12 hours, and a one-way ticket costs a minimum of 280 kuna. A train is not an option in this case.
The trip by car from Rijeka to Dubrovnik would take over 6 hours, with a cost of at least 260 kuna for fuel and 170 kuna for toll.
The air connection between Rijeka and Dubrovnik has a short stop in Split Airport, but in less than 2 hours you will be at Dubrovnik Airport. A one-way ticket starts at HRK 357, with a 19-seater aircraft from Trade Air.
Given that these domestic routes are quite unknown to the public, we would like to draw your attention to them this way, it may be more practical, faster and cheaper to travel between Croatian cities by air in the future for you.