Maritime and Coastal Command
U-boats were one of the most feared German weapons. They had the potential of severing Britain's maritime lifeline and rendering the country ineffective as a combatant. Success by the U-boat campaign would have changed the face and outcome of World War II.
The Coastal Command was in charge of taking care of the submarines. They started with 265 aircraft at its disposal, and had done a rather good job through 1940 with what they had. Most of what they had were Avro Ansons. They were dubbed faithful Annies by the pilots because of their slow reliability, yet not very good at attacking. They were backed up by a few Lockheed Hudsons and Short Sunderland flying boats.
Added to the technological challenges faced by the Coastal commands of both Britain and Canada, and later the United States, was the sheer size of the area of operation. Millions of square kilometers of ocean, compounded by the unpredictable weather of the north Atlantic, provided the physical backdrop on which the crews of aircraft with limited range had to search for their quarry.
Tactical approaches to the challenge also fell foul of the different views of the three allies. This inability to agree on tactics was also evident in the planning of methods to successfully get ships from North America to Britain; convoy or lone vessels, that was a major bone of contention.
Three challenges, before the real challenge of u-boat hunting: geography, technology and tactics. Of course another challenge was crew training. There was not the luxury of months of training and exploration of effective tactics. The war was on and the need was now. Learn as you go was a major element of the training methods available.
Closing the Black Pit, that area of the Atlantic that could not be covered by coastal commands, was the need of the allies. As the range and weaponry of the planes of the allied coastal commands improved, the effectiveness against the U-boat began to show success.