Why Merlin mission-kit swapping suits a small fleet

Why insist on swapping airborne-early-warning kits between Merlin helicopters?

It lets a small airframe pool cover several missions without carrying separate dedicated fleets.

Instead of embarking fixed groups for every mission, the Royal Navy can take a pool of serviceable Merlin airframes and configure them according to need. A carrier might embark roughly eight to twelve helicopters and shift the available machines between anti-submarine warfare, airborne early warning, and lift tasks. That avoids being trapped with four aircraft in each role when one category suffers losses or a mission suddenly becomes more important. The modular kit saves resources, though a similar Sea King concept proved too expensive for that older airframe.