I'm running a couple of careers in 1943 right now. Airplanes have been a nuisance but not horrible-yet.
It is attacking convoys that get me. I cringe everytime I get a convoy report or spot one now. I say a quick prayer and move in without too much confidence(I put on a confident face to my crew though

).
I've lost a couple boats attacking convoys in 1943 to hedgehog equipped escorts-<shudder>.
Back in 1940, I couldn't wait to find a convoy, and it took a while before I saw my first. Now in 1943, I'm happy finding singles.