Many animals move their eyes to direct and stabilize gaze. In flight, insects stabilize gaze via a pattern of head and body movements, yet their interaction remains unclear. We used a control theoretic framework to study how head and wing movements are coordinated and quantified how head movements shaped visual inputs in tethered fruit flies. Head movements reduced retinal slip error by up to 60%, slowing down visual inputs. Head movements responded to the visual stimulus in as little as 10 ms—which was more than four times faster than wing movements—suggesting a temporal order in the flow of visual information such that the head filters visual information which then elicits downstream wing steering responses. By comparing the responses of head-free and head-fixed flies, we revealed that head movements increased the strength of downstream wing steering efforts and improved coordination between the wings and visual stimulus. Fixing the head of flies had a detrimental effect on flight performance, decreasing wing gain, flapping frequency, and overall thrust, thus reducing the total mechanical power generated by the flight motor. To reveal how head movements modulate visual inputs entering the brain, we simulated an Elementary Motion Detector on a moving “head”. Head movements shifted the effective visual input dynamic range onto the sensitivity optimum of the motion vision pathway, allowing flies to encode visual motion speeds two times faster than previously thought. Overall, our findings reveal the critical role of active vision in insect flight control.