Why carrier lifts should sit just below the flight deck

Should a carrier's landing-area elevators be flush with the flight deck or several feet below it?

Usually slightly below the deck, but not four to six feet down; aircraft approach speed shapes the final compromise.

A perfectly flush lift minimizes obstruction but can create its own handling and safety compromises. Placing it four to six feet below the deck is usually too deep for an efficient landing-area arrangement. A position slightly below deck level offers a better compromise. The exact offset depends on the approach speed and behavior of the aircraft expected to use the carrier.