Helicopter patrols change Scapa Flow and carrier vulnerability

The counterfactual does not guarantee different outcomes, but it makes persistent local surveillance much cheaper. At Scapa Flow, routine patrols might notice deteriorated barriers or detect the submarine that historically sank HMS Royal Oak. Helicopters based at Gibraltar could watch the narrow approaches and exploit shallow, clear water even before airborne surface-search radar matured. Carrier patrols might also warn HMS Courageous of a submarine or reveal Scharnhorst and Gneisenau before they reached HMS Glorious. Each case remains conditional because the opposing navies would adapt too, but the common change is a larger and more continuous warning envelope around bases and ships.