This article discusses the cognitive proximity observed between competing stakeholders in the same industry – avionics. Simultaneously, we find unintentional knowledge spillover. How explain this cognitive proximity between rival actors who do not cooperate? This work is based on a statistical demonstration: cognitive proximity is measured by the degree of similarity of their knowledge bases (using patents). We highlight the existence of both cognitive proximity and unintentional knowledge spillover in a rarely studied industry: avionics. We stress the need to take account of industry-specific factors in order to explain this form of cognitive proximity. JEL Codes: L62, O30