Weird Harold wrote:The specific case that prompted the discussion of helicopter carriers is the Brazilian Navy replacing its only Aircraft Carrier with a single Helicopter Carrier. The Brazilians didn't have any carrier based AEW planes so they have always worked with land-based AEW and Patrol. Since they only have one carrier, they're NOT going to be working in conjunction with large carriers.
Other nations will have different reasons for commissioning helicopter carriers; the US, for example, uses them as floating Marine bases under the Air Superiority umbrella of fleet carriers' fixed wing and ASW shield of other battle group ships.
And the UK Invincible-class "through deck cruisers" of the Cold War were designed to support the NATO anti-submarine efforts in case of war. They allow numerous anti-submarine helicopters to be operated and maintained. They only carried a few Harriers to defend against (or prey on) Soviet maritime patrol aircraft. And you don't need all that high performance an interceptor to go after a <600 mph Tu-95 Bear.
Similarly I believe the JSDF's helicopter destroyers are primarily anti-submarine units, but also capable of using the helicopters for humanitarian or peacekeeping missions.
The US Marine corp, as already noted, uses their for airborne or air/amphibious assault. And the UK's HMS Ocean served a similar role.
Those do seem to be the two main purposes for helicopter carriers. Then depending on each operator's needs or desires they may also carry a few VSTOL aircraft for self-defense and/or ground attack - but that's secondary to their main mission of supporting a large number of simultaneous helicopter for anti-submarine, transport, or ground attack purposes.
You obviously can't use them for amphibious assault against a peer power without something else providing at minimum air denial, but anti-submarine work can often occur under land based air cover or far enough out that neither you or your enemy can reach with attack aircraft. But participating in peacekeeping often doesn't require air superiority - nor does humanitarian operations.
Not every naval ship has be to built to survive all out war with a peer; not even your most expensive ships.