[MaddogK]

I've always found that a torpedo fired without a lock always tracks the path of the last solution that was entered (your last successful lock), and have read elsewhere around here that you must hit the lock button twice without a target in view to clear the last lock and make the torpedo track straight when fired. I would assume you can also clear the last lock by sending the straight ahead bearing from the sonar console (hydrophones) to the TDC but don't remember ever trying it.