A plausible 4 December 1941 sighting is hard to arrange. The Japanese route avoided normal shipping lanes and passed through the large patrol gap between the Aleutians and Hawaii, beyond useful Catalina coverage from Kodiak. Fishing boats and merchant ships tended to operate elsewhere, and many smaller vessels lacked the long-range transmitters needed to send a useful warning. Even the cargo aircraft that historically passed about fifty miles from the force was unlikely to identify more than an isolated destroyer. The route also ran near a seam between American command areas, so geography and divided responsibility helped conceal the approach.
Chapter · 4:53-13:55
Why Kido Butai was so hard to find
The northern route exploited gaps in shipping, aircraft coverage, submarine patrols, and Pacific command boundaries.