Why long-range naval aircraft needed a second crew member

Why did the Royal Navy persist with two-seat observation fighters?

Long-range and night navigation required a navigator or wireless operator; the naval observer system was an additional benefit, not the underlying reason.

The second crew member was principally a navigator and wireless operator, rather than merely a way to ensure Royal Navy representation in the cockpit. Long-range flight over water required chart work, star sights, and position calculation that a pilot could not safely perform while flying. The same second pair of eyes also mattered for reconnaissance and lookout duties. The Fleet Air Arm's turn toward two-seat designs coincided with its 1933-34 emphasis on finding and attacking targets at long range at night.