The Reason Behind Japanese Aircraft Carrier Deck Markings

The Reason

If you’ve ever noticed the distinctive arrow markings on the forward decks of Japanese aircraft carriers in WWII footage, you may have wondered about their purpose. While several theories exist, the true explanation is surprisingly straightforward.

Aircraft carriers operate directly into the wind during flight operations to provide lift for takeoffs and landings. However, wind direction and speed are rarely constant. Sudden gusts or turbulence can push planes off their approach path, forcing aborted landings—or worse, sending them into the sea.

To solve this, the Imperial Japanese Navy developed a clever visual system: arrow markings paired with a steam vent. Lines were painted on the deck in 10-degree increments, with shorter marks for 5-degree intervals. A small steam valve at the arrow’s convergence emitted a thin stream of steam, accurately showing wind direction against the markings.

This simple yet effective system allowed pilots to detect wind shifts from a distance, adjust quickly, and safely complete their landings—an innovation that made flight operations significantly safer.