An analytical survival modeling framework for reducing helicopter emergency medical dispatch cancellations

Helicopter emergency medical services (HEMS) constitute a significant part of the prehospital care system and can improve medical outcomes of the most critically injured patients. Due to the time-sensitive situation of helicopter dispatch, the service faces high cancellation rates, where helicopters are dispatched yet provide no patient assistance. These cancellations waste resources, occupy crews, and reduce availability for true emergencies. We propose a proof-of-concept framework that strategically delays helicopter take-off based on dispatch characteristics to balance cancellation risk and patient outcomes. Using Cox proportional hazards models and real data from a Dutch HEMS, we quantified the trade-off between postponement time, cancellation rate, and patient morbidity, visualized through Pareto optimality plots. The results show that modest delays can sharply reduce cancellations with minimal effect on patient outcomes in the studied patient group. Given the promising results in our case study, we provide a scheme of our approach to be implemented in dispatch systems. This framework can be integrated into dispatch systems across regions to improve efficiency, conserve resources, and sustain high-quality prehospital care.