Three missed opportunities in carrier aviation

What were the three biggest missed opportunities in carrier aviation?

The examples are Courageous and Glorious, the absence of an American carrier in strike range at Pearl Harbor, and the Royal Navy's stalled single-seat fighter programme.

Courageous should not have been exposed in anti-submarine hunting, and Glorious should have sailed as part of a protected task group with aircraft operating. Used properly, either carrier could have influenced later operations far beyond the moment of its historical loss. The delayed American carrier force near Pearl Harbor was a missed chance to strike back, though normal operational delays created that timing rather than a single bad decision. A specifically aviation-focused example is the Royal Navy's single-seat fighter programme, which failed to produce results before the war. These cases separate avoidable employment failures from opportunities lost to timing, policy, and development constraints.