Never successfully torped a ship from a plane have scored 60 CV's down in a tour with PT boat.
The key is your position relative to the CV group's direction and how many other friendlies are around.
With too many friendlies, the cv will turn as a friendly spends himself against the hull in a poorly planned attack and your newly launched torps miss the boats.
Since torps run about the same speed as a CV group, you have to be positioned almost directly in front of a cv coming toward you.
If you see me on, ask about torping from a PT boat and I will demonstrate the technique.