Increased competition within global airline industry initiates consolidation activities on entering into different modes of cooperative arrangements including, franchising, code share agreements, alliances, mergers and acquisitions. Selecting the optimal business model means implementation of sustainable competitive strategy as one of the key airline business challenges. Characteristics and trends in airline competition worldwide were analyzed by using correlation and regression metrics. European air transport competition analyzes include specific Southeast Europe topics. The liberalization of the Croatian air transport market has significantly affected the increase in demand in the international scheduled passenger traffic from the year 2004. Air transport in Croatia is growing much faster compare to the maritime and land transport sectors. A significant structural change in the aviation market due to the strong increase of low-cost carriers share in international scheduled traffic occurs. At the same time, the share of domestic scheduled and charter transportation is stagnating. Croatia Airlines in restructuring process provided in the period 2011 -2015 recognized necessity to justify market position through optimal network strategy.

Airline ancillary revenue which refers to non-ticket revenue sold directly to passengers or indirectly as part of their travel experience, has become a mandatory component for the revenue mix of all airlines as well as a key reason for the improved financial performance of the airline industry in the recent years. It is generated by a large amount of activities that include „a la carte” services such as fees for checked bags, frequent flying miles to airline partners, miscellaneous sources like advertising and commission-based products such as inflight retail, and car rentals - virtually any service added to the core transportation service. Contribution of ancillary services to the total revenue streams of airlines has been increasing substantially over the past decade. In 2007, the top ten airlines, as rated by total ancillary revenue, generated $2.1 billion, while ten years later, the top ten airline total has reached $29.7 billion. The paper explores the recent growth and trends in ancillary revenue in the airline industry, particularly within in the last ten years and identifies significant differences in ancillary sources with regard to carrier type. Low-cost carriers pioneered the practice of charging for supplementary services that were previously provided free of charge by seeking revenue from checked bags, assigned seats and extra leg room seating. Traditional airlines moved from all-inclusive booking arrangement and started to adopt add-on bundling practice when selling flight tickets taking advantage of low headline price. Their ancillary revenue mostly comes from the use of frequent flyer program, a mix of baggage fees and premium seats. Top airlines in overall ancillary revenue performance measured as total revenue, a percent of revenue, or on a per passenger basis are determined in the paper and new trends in creating ancillaries are elaborated. In order to improve profit performance, the airline revenue management and distribution systems should consider total revenue from each passenger, by linking his ticket value and his ancillary revenue potential.

Air transport industry is one of the very important businesses worldwide. Th e global recession in the years

Ancillary services in air transport represent a set of services provided to passengers to choose from, enabling them to enhance their travel experience while accumu-lating additional airline revenue. Low-cost airlines pi-oneered the practice, but the separation of ancillary services from the basic service has become an intense-ly growing trend in the air transport industry over the last decade. This practice has enabled low-cost airlines to significantly reduce the price of the basic service. To remain competitive in an era of transparency provided by search engines, traditional airlines offer ancillary ser-vices in addition to the basic service. To meet the passen-ger’s needs, a whole range of ancillary services has been created. However, existing revenue management systems do not take this ancillary revenue into account when cal-culating reservation limits. If the airline knew that an in-dividual passenger is willing to pay more for ancillary services, the system would be able to adjust the availabil-ity of the service for that passenger during the booking process. A review of research on passengers’ willingness to pay for ancillary services is presented in the paper, as well as a review on research on the personalisation of ancillary services and challenges of integrating person-alised pricing into existing revenue management systems.

Airline revenue management systems are used to calculate booking limits on each fare class to maximize expected revenue for all future flight departures. Their performance depends critically on the forecasting module that uses historical data to project future quantities of demand. Those data are censored or constrained by the imposed booking limits and do not represent true demand since rejected requests are not recorded. Eight unconstraining methods that transform the censored data into more accurate estimates of actual historical demand ranging from naive methods such as discarding all censored observation, to complex, such as Expectation Maximization Algorithm and Projection Detruncation Algorithm, are analyzed and their accuracy is compared. Those methods are evaluated and tested on simulated data sets generated by ICE V2.0 software: first, the data sets that represent true demand were produced, then the aircraft capacity was reduced and EMSRb booking limits for every booking class were calculated. These limits constrained the original demand data at various points of the booking process and the corresponding censored data sets were obtained. The unconstrained methods were applied to the censored observations and the resulting unconstrained data were compared to the actual demand data and their performance was evaluated.