Carrier ASW helicopters add depth to the escort screen

If the carrier's escorts already have anti-submarine helicopters, why does the carrier air group need more of them?

Carrier helicopters create the numbers and maintenance depth needed to keep several aircraft airborne, investigate multiple contacts, and mass two or more helicopters against a submarine.

Six escorts may each carry a helicopter yet still provide only a small number continuously airborne once maintenance, crew cycles, and readiness are considered. Several contacts can exhaust that screen quickly, especially when doctrine calls for two aircraft to cooperate against one submarine. A carrier pool of six or twelve additional helicopters can sustain dipping-sonar and sonobuoy searches, while escorts serve as refuelling and rearming lily pads beyond the carrier deck. The larger air group can mass aircraft on a real contact, investigate another uncertain contact at the same time, and retain enough reserve capacity for the next sortie cycle. Detaching a surface escort to investigate a contact is another option, but an air threat or a shortage of dedicated anti-submarine escorts can prevent it.