A systematic review and research agenda on the strategies of air freight integrators

This study provides a systematic review of the strategic evolution of air freight integrators and develops a structured research agenda. Using the PRISMA 2020 framework, we synthesise 63 peer-reviewed studies to analyse how integrators formulate and adapt their strategies across three interrelated pillars: network structure, cost structure, and service differentiation. The review makes two main contributions. First, it establishes a unified operational definition of air freight integrators as time-definite, end-to-end logistics providers that combine air and ground transport under a single contractual and operational framework, exercising vertical integration through control of critical assets, capacity, and information systems. Second, it offers a cross-regional synthesis that explicitly compares Western incumbents (FedEx, UPS, DHL) with emerging Asian integrators (notably SF Express and YTO Express), moving beyond firm-specific or region-isolated analyses. The findings show that Western incumbents predominantly rely on highly centralised hub-and-spoke networks, while Asian integrators operate more hybrid and bidirectional configurations aligned with dense e-commerce demand. Across cost studies, economies of density are robust, while scale effects depend on network maturity, methodological choice, and business model configuration, helping reconcile contradictory results in earlier research. Evidence on service differentiation is more fragmented but indicates convergence in strategic logic, with both incumbent and emerging integrators shifting toward higher-value, specialised services while adapting offerings to regional market conditions. Overall, the review shows that integrators cannot be treated as a homogeneous category: strategic outcomes reflect deliberate trade-offs between network design, cost management, and service scope shaped by regional and institutional contexts. The paper concludes by outlining a focused research agenda that prioritises comparative analysis of Asian integrators, dynamic network-cost linkages, and theory-driven studies of service differentiation.