I've had the same lack of air contacts to date, bosje. (Early Nov 42 for me) I've got the improved SDworking , but only plane I spotted was near Hong Kong on last patrol before my Porpoise class got rebased from Perth to Midway.
BTW, I wasn't trying knock down your previous post. I agree that those large splits are harder to sink than first assumed. Given my usual bad luck, I've just assumed that somehow the randomizing functions with torp damage are working against me.
My latest victim I spied at long range and ID'd as another LOS. Given teh excellent visibility and my initial quick plotting, I figured I'd try to track him all the way in on sonar and then give him four tubes using the O'Kane method, so as to avoid my scope being spotted any earlier than necessary. Turns out he was just a little guy, but I gave him four tubes from my new Gato anyway. Poor guy erupted like Vesuvius, and two bow squared off the front of the ship nicely. No life boats spotted.