Air attacks

[Pascal]

We know most of u-boote have been sunk by planes; but in the game, radars work so well, it is impossible to be in surprise with an air attack. It's always the same way: radar signal, then dive, then surface with smile, then radar signal, then dive, etc ....
So, my question: how so many sub have been sunk with such good radars ?

or perhaps radars in the game work to much well;