Isoroku Yamamoto (Speculation)

[Blackadder1916]

I wonder about this. The naval vessels would have taken time to get moving, but Pearl Harbor only had one exit, so they would have been trapped in the harbor allowing little chance for escape. How many U.S. aircraft could have been airborne to defend the fleet, and how much (effective) anti-aircraft fire could have been put up to deter the attackers? All interesting questions. I think considerable damage could still have been done to the U.S. battleships, but the raid would simply have been much more costly to the Japanese pilots.  . . .

The premise that if the reports of junior (radar) personnel had been heeded, the outcome of Dec 7 may have been significantly different is a bit of a red herring.  While it is true that the report of a radar sighting was misinterpreted to be 'perhaps an incoming flight of B-17s', it must be recognized that the 'Information Center' (located at Fort Shafter) that received the report was basically shut down for Sunday routine and the only pers on duty were a switchboard operator and the duty officer (an inexperienced Lt. who had only been there a few days).  The first radar sighting was made at 0702 and the duty officer made his decision that further action was not necessary at approx 0720.  By 0740 the Japanese had begun their attack run (early due to error) at Ford Island and Hickam Field and the order to begin the general attack was sent by 0749.  It should also be considered that, while the Army was "ignoring" the radar reports, the Navy was "ignoring" the reports of submarine contact from the WARD.

What was probably the greater error (re the radar) was inadequate air defence C3 as well as poor Army/Navy liaison and a mindset (perhaps more so in the Navy) that while war was expected, they did not expect the Japanese to show up at Hawaii and believed that the fleet would be at sea when they would meet and engage the enemy.  Though the deployment of radar on Oahu was probably not the most professional due to an unfamiliarity with this new technology by many higher in the food chain, from a practical aspect, the only action that may probably have been taken (should the radar report had been heeded) would have been to move up to Alert No. 2 or 3, disperse planes on the ground and break out ammunition.

 

[Sito Origami]

The premise that if the reports of junior (radar) personnel had been heeded, the outcome of Dec 7 may have been significantly different is a bit of a red herring.  While it is true that the report of a radar sighting was misinterpreted to be 'perhaps an incoming flight of B-17s', it must be recognized that the 'Information Center' (located at Fort Shafter) that received the report was basically shut down for Sunday routine and the only pers on duty were a switchboard operator and the duty officer (an inexperienced Lt. who had only been there a few days).  The first radar sighting was made at 0702 and the duty officer made his decision that further action was not necessary at approx 0720.  By 0740 the Japanese had begun their attack run (early due to error) at Ford Island and Hickam Field and the order to begin the general attack was sent by 0749.  It should also be considered that, while the Army was "ignoring" the radar reports, the Navy was "ignoring" the reports of submarine contact from the WARD.

What was probably the greater error (re the radar) was inadequate air defence C3 as well as poor Army/Navy liaison and a mindset (perhaps more so in the Navy) that while war was expected, they did not expect the Japanese to show up at Hawaii and believed that the fleet would be at sea when they would meet and engage the enemy.  Though the deployment of radar on Oahu was probably not the most professional due to an unfamiliarity with this new technology by many higher in the food chain, from a practical aspect, the only action that may probably have been taken (should the radar report had been heeded) would have been to move up to Alert No. 2 or 3, disperse planes on the ground and break out ammunition.

Well stated. And even had American pilots found themselves somehow with fuelled and armed aircraft with pilots in the general vicinity of their planes, with clear airfields and enough time to marshal them aloft - Michael Bay movies and Death Star Trench scenes aside - what possible good raw pilots in P-36 and P-40s could have done against Japanese pilots in A6Ms remains to be seen. The results may have been surprising, though - the US did manage to fly 25 sorties in the event, and the USAF credits six pilots with 10 victories, six of them by Lieutenants Taylor and Welch, both in P-40s. Three of the other four kills, one apiece by four P-36 pilots, were unverified by the Japanese and there is speculation that they were actually lost to anti-aircraft fire. Then again, the number of friendly fire incidents would probably have increased as well - naval aircraft from U.S.S. Enterprise were shot down later in the day, for example. But as I stated earlier, I have to agree with you that it is a red herring, and that I believe that this early warning would have made the attack costlier for the Japanese pilots by some degree but probably had little material effect on the outcome of the attack itself.