Crowsnest AEW within a wider flight-deck plan

What AEW capability were Queen Elizabeth and Prince of Wales to use, and why a helicopter system instead of fixed-wing aircraft?

Merlin Crowsnest; fixed-wing AEW is better, but Merlin can serve the available carriers and amphibious decks as part of a common aircraft system.

Queen Elizabeth and Prince of Wales were to use Crowsnest-equipped Merlin for airborne early warning. In July 2020, the delayed system was expected to deploy with the following year's task force. Fixed-wing aircraft are normally the stronger AEW platforms, but the British choice was bounded by the aircraft and decks actually available. The intended force had two carriers and three LHDs, allowing a common AEW, strike, and lift system to move across five flight decks. That redundancy would matter whenever carriers or amphibious platforms were unavailable.