ABOARD THE USS GEORGE H.W. BUSH—An unmanned plane piloted by a string of computer algorithms landed on an aircraft carrier for the first time Wednesday as the tailhook of the drone known as “Salty Dog 502” caught the third wire of the ship’s deck and abruptly came to a halt.

Top Navy officials repeatedly hailed as historic the successful landing—which after countless tests and simulations on land was not much in doubt.