 Following the Indo @-@ Pakistani War of 1965 , Pakistan invested heavily in modern submarines and long @-@ range torpedoes . In response , India opted to procure six Westland Sea Kings from Britain in 1969 , for ASW duties , designated as <unk> . The purchase also included the provision of air @-@ <unk> homing torpedoes for use against submarines . The delivery of the aircraft began a few months before the Indo @-@ Pakistani War of 1971 . Due to training shortfalls on the new helicopters , Sea King operations were considerably restricted during the 1971 war ; by November 1971 , increased aircrew experience had enabled offensive anti @-@ submarine operations to be conducted . The Majestic class aircraft carrier INS Vikrant was also refitted in 1972 – 1974 to enable extensive Sea King operations , becoming the carrier 's primary anti @-@ submarine aircraft . 
