Why would a helicopter-equipped anti-submarine surface ship still carry torpedoes?
Short answerThey provide a last-resort return shot if a submarine gets close enough to place the surface ship in immediate danger.
NotesA viewer notes that the Soviet Moskva carried torpedoes even though helicopters extended its anti-submarine reach. Surface ships often retain torpedoes as a last-resort anti-submarine weapon. If the submarine is already close enough to fire, the ship is in grave danger. The tubes preserve a chance to kill the attacker even in that worst-case engagement.