A landing signal officer or landing safety officer (LSO), also informally known as paddles (United States Navy) or batsman (Royal Navy), is a naval aviator specially trained to facilitate the "safe and expeditious recovery" of naval aircraft aboard aircraft carriers.[1] LSOs aboard smaller air capable ships that launch and recover helicopters are informally known as deck. Originally LSOs were responsible for bringing aircraft aboard ship using hand-operated signals. Since the introduction of optical landing systems in the 1950s, LSOs assist pilots by giving information via radio handsets.