firing antiaircraft practices in early February, the ship proceeded to the Destroyer Base, San Diego, for her yearly hull inspection in the floating drydock USS ARD-1 and then proceeded to the Mare Island Navy Yard for a brief overhaul. Following those repairs, Aylwin arrived at San Diego on the 6th, just in time to participate in Fleet Problem XIX. The "Black" Fleet put to sea from San Diego at 03:25 on 15 March. As part of the "White" Fleet, Aylwin got underway at 1640 and soon joined the remainder of Destroyer Flotilla 1 and the aircraft carrier . Searching for the enemy "main body" on the 17th, she fell in with , , and on the following morning. That afternoon, the cruisers made contact, attacked, and retired under cover of a smoke screen. Aylwin regained sight of the "enemy" and took up a position a safe distance astern to trail them through the 19th. After fueling from on the 20th, the destroyer conducted exercises in subsequent phases of Fleet Problem XIX until supporting a mock landing at Lahaina; at the outset, she lay-to between the islands of Molokai, Lanai, and Maui before standing in toward the "beachhead" to support the landing of troops. She conducted a brief minesweeping drill before refueling from and then anchoring at Lahaina Roads for a brief respite. From 4 to 8 April, Aylwin again was underway participating in further exercises before putting into Pearl Harbor. When the fleet sortied on the morning of the 18th, she ranged ahead of the departing battleships alert for possible "submarine" activity. Ultimately, Aylwin participated in the closing phases of Fleet Problem XIX, which had been conducted in three separate phases, each a small fleet problem in itself. As in Fleet Problem XVII, the exercises also tested the ability of the fleet to seize and hold advanced bases, indicating the Navy's Pacific-minded planning. The destroyer returned to San Diego on 28 April and, on 9 May, resumed her coastwise training schedule. She underwent brief upkeep alongside Whitney before getting underway on 21 June for the Pacific Northwest and cruising along the coast through July, touching at such places as Port Angeles, Washington; Ketchikan, Territory of Alaska; Humpback Bay, Wrangell Narrows, Taku Inlet, Yakutat Bay, Sitka, Seattle; and finally, Portland, Oregon. She returned via San Francisco to San Diego in mid-August, underwent tender upkeep alongside Whitney, and conducted training off the