The Bay of Biscay technology contest

How effective was Coastal Command against U-boats entering and leaving their French bases through the Bay of Biscay?

It was fairly effective when British sensors held the advantage, but results fluctuated as German countermeasures caught up.

The Bay of Biscay campaign followed a recurring cycle rather than giving the Allies a permanent technical advantage. Airborne radar and Leigh Lights made patrol aircraft highly effective for periods, after which German Metox receivers and other countermeasures reduced their success until another edge emerged. Anti-submarine warfare depended on adaptation and training alongside the individual weapons.