How hard would it have been for a Japanese observer to report American carriers leaving Pearl Harbor?
Short answerVery hard: the report had to survive a long communications and analysis loop before the fleet could retarget.
NotesThe practical delay ran from an observer through the intelligence network and headquarters to the striking fleet. A local sighting first had to reach the person or station authorized to transmit it, then be sent to Japan, decoded and interpreted, and finally retransmitted to the Kido Butai. Long-range radio equipment was large, conspicuous, and vulnerable to interception rather than a modern burst-transmission device. Every stage consumed time while the carriers continued moving. Real-time target updates were therefore much harder than a simple map of presumed spies suggests.