I was ASW as well, and it was a long time ago too. My rating was OTA (SOSUS). We used to work with the P3 crews from time to time, and as far as I was aware they only used passive and/or active sonobuoys. I recall they helped, along with a few surface ships, chase a Russian sub out of the Puget sound. Their fast-attacks (Russian) make a lot of noise when they leave with their tales between their legs, but I'm sure that crew didn't notice. EVERONE went active in the end, lol.