Normally, the air coverage is greatly increased 1943 onward compared to the first years of the war. In addition, allied aircraft use radar. Also, you have to take into account the various task forces patrolling in the North Atlantic: they bring aircraft with them which are launched from the aircraft carriers. It is expected that your U-boat will be harassed due to their activity.
However, the correct depiction of the frequency of these patrol aircraft, their armament and behaviour is something totally different. For this reason (and many others) I would say that you might want to check what the available supermods have to offer.
Have a nice weekend.
