This paper examines the air route development process, including key stakeholder engagement, to identify essential factors in the successful establishment of new international air services at regional airports. Data from semi-structured interviews with airports, airlines and destination marketing organisations were analysed to provide perspective regarding Adelaide, an Australian regional international airport. The research proposes a model that maps out the relationships and processes of primary and secondary stakeholders for air route development and finds route profitability and stakeholder relationships as critical factors for air route development. The airport emerges as a leading actor in driving route development. Efficiencies and broader regional objectives are realised when the airport collaboratively engages with wide-ranging stakeholders. The paper provides future research direction to address identified limitations and provides recommendations to guide other regional airports and airlines in establishing new international air services.