HMS Formidable and the armoured-carrier tradeoff

Interwar exercises involving Courageous, Glorious, Furious, and the Mediterranean and Home Fleets suggested that some attacking aircraft would penetrate a carrier's defenses. British planners therefore faced a choice between carrying more aircraft and ensuring that one or two expected 500-pound armour-piercing bomb hits would not disable the ship. The armoured hangar chosen for HMS Formidable accepted a smaller air group in return for greater resistance to damage. That tradeoff made sortie rate, aircraft reliability, maintainability, and repair especially important because each aircraft had to contribute more consistently.