The introduction of larger capacity and longer-range aircraft into air traffic operations has provided for more comfortable and cost-effective flying. These aircraft additionally serve as a pre-condition for expanding the traffic network, allowing entry into new markets and the development of airline traffic operations.

Selecting which types of new aircraft should be included in an air company's fleet is a complex and serious undertaking for any airline. The success of the airline - and even the question of its survival - may depend on these decisions. It is thus interesting to look at the past and see how the first domestic air carrier Aeroput, and its successor Jat Airways, coped with these important issues in previous decades.

Starting with the five-passenger-seat aircraft "Potez 29", which Aeroput purchased from France in 1927, and leading up to the ATR-72 aircraft introduced into the JAT fleet in 1990, both companies used 19 different types of passenger aircraft, manufactured by sixteen well-known world manufacturers, for their scheduled flights. Only two aircraft (in 1935) were manufactured by the local airline industry.

In its early days, Aeroput only flew over lowlands and only one-engine aircraft were used. When routes were extended over the heights of the Dinara mountain range in 1933, the company had to introduce aircraft with two and three engines into its fleet, which provided for a safer flight, a larger number of seats and the possibility of carrying larger loads.

The expansion of international routes and an increase in passenger numbers enabled Aeroput in 1937 to acquire from the USA the most modern aircraft of the time with a metal construction, the Lockheed Electra 10, thus ranking the company among the more successful air carriers in Europe.

Post-war air traffic was renewed with a re-construed military transporter plane, the Douglas DC-3, and Junkers JU-52. They had been the only aircraft in the JAT fleet until 1954 when more modern aircraft, the Convair 340 and 440, were purchased, which increased travel speeds to over 500km/h and offered pressurized cabins and other conveniences for passengers. These aircraft enabled Yugoslav Airlines to introduce new intercontinental flights and to compete internationally with European air carriers.

By the end of the 1950s, the first long-haul aircraft with four DC-6B engines were introduced, making it possible for JAT to arrange charter flights to any continent, thereby announcing its presence in intercontinental traffic.