I've never actually encountered aircraft while spanking convoys, suppose it's just because I'm a pretty flawless U-Boat commander
But one thing that does annoy me when attacking convoys is I always get fixated on a target, line up my front to a tankers arse and fire my torpedo's, but watch every second until I see the bugger is well and truly in a spot of bother. Too often this means I get coastal merchants nosediving into my conning tower unknowingly (Both to him and me up until the noise begins). Occasionally though I'll spot the trouble and take evasive action, jab 'D', then go to external and follow my torpedo some more, then usually I'll sit there and watch the thing blow up, then slowly sink and wind its way down to the murky depths to the mercy of the dreadful spindley killer fish. But naturally, I forget completely about my crew who are probably too terrified to speak up at their brutal, despot commander and just let themselves get crushed at unrecommended depths and meet a similar demise, if a slightly more embarrassing one.
Course, the same thing sometimes happens with me leaving my periscope up to watch my soon to be damaged prey and I'll find myself with bullets, shells and depth charges raining down on me.
But also in earlier years when convoys were defenceless I'd just charge straight at them surfaced, coming up alongside the most valuable game with my deck gun being quite ungentlemanly, but again my external camera went overused and not just twice but three times I ended up sailing straight into merchants, I even got rammed once by a C3 and I never bloody saw it coming, although it was a pretty impressive if worrying sight as I very quickly switched to bridge once I heard the familiar sounds of U-Boat steel twisting.
I also keep hitting enter as I muck around with time compression, squandering valuable torpedo's