Aircraft carriers did not accompany the Normandy landings for three practical reasons. Airfields in the United Kingdom already supplied enough aircraft close to the beaches, making carrier flight decks redundant. Carriers manoeuvring through the assault area would also have complicated the movement of slow landing craft and supply ships. Their flight operations required much more clear sea room, with one estimate increasing the mine-swept area fivefold, so excluding them reduced risk and logistical burden rather than discounting naval aviation.
Notable Point · 55:08-56:01
Why Overlord used land-based aircraft instead of carriers
Britain already provided a vast air base, while carriers would have obstructed the invasion lanes and multiplied the water that minesweepers had to clear.