Tay T.R. Koo a,* , Yi-Lung Chen a , Zhenyu Zhang a , Kan-Lin Lu a , Ruwen Deng a , Trent Banfield b , Andreas Papatheodorou Elsevier

The sustainability characteristics of international air routes: A composite index approach

Due to their multidimensionality and complexity, indicators are often used to measure and track progress towards travel and tourism sustainability at a destination/country level. These sustainability in￾dicators are often forms of composite indices and can be used to drive change at national and institutional level. Conceptually, “composite indicators are based on sub-indicators that have no common meaningful unit of measurement and there is no obvious way of weighting these sub￾indicators”, and technically, they are “mathematical combinations of a set of indicators” (Saisana, 2004, p. 1). Although they are not fully in￾clusive (see for example issues emerging with respect to university rankings, which use composite indices), the society accepts the use of indices for a variety of purposes including public debate, complex de￾cision making, strategic marketing, benchmarking and to evaluate/drive performance based on Specific, Measurable, Achievable/Agreed, Rele￾vant/Realistic, and Timebound (SMART) objectives (OECD, 2015). One of the main challenges in the design of sustainability indicators is breaking down the complex multidimensional concept into manage￾able units of information: they need to simultaneously capture different aspects of sustainability, aid ease of interpretation, and be appropriate for complex decision making (Pinter et al., 2018). A composite indicator may have limits in incorporating all the significant properties of a system. However, its advantage lies in synthesizing complex concepts, and in acting as a tool of “negotiation” whereby a community of peers use it as a common measuring rod; thus, the underpinning methodo￾logical framework of a composite indicator is that which allows the integration of a broad, non-equivalent and potentially conflicting viewpoints, in order to reduce the complexity of issues such as sus￾tainability into intermediate objectives that can be observed and measured (Nardo et al. 2005). In fact, it has even been suggested that without indicators the term sustainability is meaningless (Butler, 1999). To this end, building indicators is an important pathway in pursuit of a comprehensive route-level cost-benefit analysis, which offers advan￾tages when making sustainable choices. The United Nations World Tourism Organization (UNWTO) defines sustainable tourism as “tourism that takes full account of its current and future economic, social and environmental impacts, addressing the needs of visitors, the industry, the environment and host communities” (UNWTO n. d.). Operationalising such a complex concept through an indicator framework is not an easy task. Glyptou et al., 2014 observe that the great number and variety of sustainability indicators highlight the lack of consensus over the most appropriate process for the devel￾opment of universal indicator framework. They note this absence is due to the multidimensional nature of sustainability and the great demand on volume and variety of data required for the evaluation; consequent