A new technique for the assessment of Team Situation Awareness (TSA) accuracy based upon post task Critical Decision Method structured interviews was developed and tested using 39 combat-ready F/A-18 pilots. Pilots undertook a number of simulated air combat scenarios, flying in flights of four aircraft against a formation of enemy aircraft. Results showed a strong curvilinear relationship where high TSA accuracy resulted in higher performance in some areas of air combat, measured with friendly losses and kills. There were diminishing returns in performance as TSA accuracy increased. This may explain why previous studies on air combat have found relatively weak relationships between situation awareness and performance where the relationship has been assumed to be linear.