Pearl Harbor Betrayed
Page 20
But if Kimmel had relied on that example and deployed a partial search from the west to northwest, his scout planes would have missed the Mitsubishis, Nakajimas, and Aichis that descended from due north on 7 December.88 Prior to the Japanese attack, Kimmel, his senior air commander Halsey, and his intelligence chief Layton all expected that any air attack attempted against Oahu would be made from the Marshalls, to the southwest. If a partial search sector were designed to include the southwest, as seems likely, the patrols would have been even farther removed from due north. Of course, the sector searched daily could have been rotated around the compass rose, in a kind of Russian roulette, but such a plan as that would not have avoided the second major question: how would a maximum effort around 128 degrees have averted the physical attrition of planes and crews that undermined the full compass search? As Kimmel told the JCC: “I decided that I could not fritter away my patrol-plane resources by pushing them to the limit in daily distant searches of one sector around Oahu—which within the predictable future would have to be discontinued when the patrol planes and crews gave out.… Had I directed their use for intensive distance searches from Oahu, I faced the peril of having these planes grounded when the fleet needed them and when the war plan was executed.”89
Some Kimmel critics have asked why he did not mount at least a narrowly conducted search employing just a few aircraft over some arguably “more dangerous sector” as a way of covering his behind in the event a Japanese attack did materialize. Kimmel anticipated that meretricious argument during the JCC hearings: “Now I might have made a token search and I might have been able to come here and say I made a token search. It was not worth anything but I made it, and therefore I am all right. I did not do that. I have never done that kind of thing, and I will not do it.”90
Had a daily patrol been run due north to a range of seven hundred miles, what might the pilots and crews, who had no radar, been able to see with their Mark I eyeballs, even when enhanced by 7×50 binoculars? Not very much or very clearly, particularly if they did not know what to look for. Going north from Oahu there is an extensive weather belt characterized generally by low ceilings, squalls, rain, and low visibility. A Pacific region meteorologist in Honolulu told the writer that intense low pressure systems cross the area north of Oahu west to east, one after another, during December. And a meteorologist-forecaster at the National Weather Service Forecast Office at the University of Hawaii said that typical of weather systems to 600 miles north of Oahu in December are stratocumulus cloud bases of 2,000 feet, and tops of 6,000 to 7,000 feet.91 Aircraft having to fly below 2,000-foot cloud bases would have a drastically reduced radius of visibility. Japanese pilots who participated in the attack reported later that on 6 and 7 December the skies north of Oahu were overcast. Vice Admiral David C. Richardson, USN (Ret.), longtime Navy pilot and, in his last assignment, deputy commander in chief, Pacific Fleet, has written about those latitudes in a letter:
The areas to the north are in the tradewinds. 15 to 25 kt. wind strength is usual. Seas are normally choppy. Cumulus clouds scud. These weather factors strongly affect visibility required to see even large ships like carriers at sea. Wakes rapidly disappear. I can’t begin to count the times I have searched for my carrier on return leg and suddenly spotted it looming large and near. (Nor my feeling of relief.) Widespread rain squall conditions were more to be feared than Japanese fighter pilots.92
We know something about the conduct of a daily intensive air search out of Oahu in this period of history, because, in the wake of the events of 7 December, distant reconnaissance was immediately undertaken there utilizing surviving patrol aircraft strength and PBY-5 as well as B-17 reinforcements that were rushed to the island from the mainland. Kimmel’s replacement as CINCPAC, Admiral Nimitz, was convinced that “the attack of 7 December will be followed by others.”93 He was proved wrong in that, but the distant reconnaissance flights he commanded brought together some reliable data pertinent to what might have been attempted prior to 7 December, if Kimmel had thought the flights advisable. On 7 January 1942, Nimitz had a total force of 67 PBYs and 42 B-17s, but each day, because of maintenance and crew rest requirements, he could only send out 25 of the former and 12 of the latter. The result was that, while he had hoped to cover 360 degrees, his long-range aircraft were covering only 290 degrees to a range of 700 nautical miles. Neither the PBY-5s nor the B-17s, it turned out, could achieve a radius beyond 700 miles, with reasonable margin for safe return, while carrying bombs, as they were mandated to do under a war alert—depth charges against submarines in the case of the PBYs. The remaining 70 degrees of the compass rose was covered, inadequately, by B-18s, Vought OS2U-3 Kingfishers and VJs to distances of 200–300 miles.
Aircraft departed on search daily at 0600. The ground speed of a two-engined PBY during search averaged 100 knots, taking into account that one of the aircraft’s legs, outbound or inbound, had to contend with headwinds, particularly in the northern quadrants. Average ground speed of the four-engined B-17 at low altitudes was 150 knots. Flight time per search for a PBY was 16.5 hours; that for a B-17 11.7 hours. Average radius of visibility for the PBY was 15 miles; for the B-17 25 miles. The pilot’s rule of thumb was that the separation between his outbound and inbound tracks at the extremity of his range was double the distance of his visibility. If visibility was 15 miles, he would travel a 30-mile leg along the outer rim of the search perimeter before turning home to base. The divide narrowed as he approached base. In the month of January the PBY flew its last 550 miles in darkness.94
Applying these data to what is known of the Japanese strike force’s approach to Oahu yields interesting material for speculation. It is a given that visual detection of that force on the night of 6–7 December was not possible because of darkness. But, it may be asked, could the Japanese carriers have been sighted during the daylight hours of the day before, by a patrol aircraft flying the 0-degrees (north) sector to the maximum scouting range of a PBY or B-17? The answer is dependent, of course, on the known position times of the Japanese carriers. The “Japanese Attack Plan” reconstructed from postwar U.S. military interrogations of Japanese naval officers specified that the striking force was scheduled to rendezvous for refueling and supply on 3 December at point C, latitude 42 degrees north, longitude 170 degrees west, well northwest of Oahu. The force was then to proceed from the rendezvous point southeast to point D, latitude 31 degrees north, longitude 157 degrees west, arriving at that position, about 575 nautical miles north of Oahu, at 1130 on the sixth. From that point, following a topping off of fuel tanks, the carriers would begin a sprint south down the 158 degree meridian at twenty-four knots toward a launch position at point E, latitude 25 degrees north, longitude 158 degrees west, or 230 nautical miles due north of Oahu.95 Twilight on the sixth began at 0508, sunrise was at 0626, sunset was at 1719, twilight ended at 1838. Moonrise was at 2005.
From the tracking chart we can calculate that a PBY-5 taking off on the sixth at 0600, an average time to be “on the step” in Kaneohe Bay, and flying north along the 158 degree meridian at 100 knots would reach 31 degrees north, 158 degrees west at approximately 1145 on the clock while the carriers were refueling to the east outside the PBY’s visibility range; though a flight along the 157-degree meridian would intercept the refueling carriers at approximately 1204. Similarly, we can calculate that a B-17 lifting off from Hickam Field at 0600 and proceeding north along the 158-degree meridian would pass west of point D at approximately 0952 when the carriers were still to the northwest outside the aircraft’s twenty-five-nautical-mile visibility range; however, a flight north along the 157-degree meridian would place the B-17 within its visibility range of the still southeast-bound carriers for a window of approximately seventeen minutes, from 1010 to 1027. These positions and times are highly speculative. Assuming that the Japanese carriers lay within the PBY’s average fifteen-mile radius of visibility, or the B-17’s average twenty-five-mile radius, what was the likelihood of their being sighted? Weather
conditions would go far in determining the answer. From Japanese aviators—the official records, including deck logs and war diaries, were largely destroyed shortly before the Japanese surrender96—we have partial meteorological information. Captain Fuchida Mitsuo, who led the air attack, wrote in 1952, “We had maintained our eastward course in complete secrecy, thanks to thick, low-hanging clouds. Moreover, on 30 November, 6 and 7 December, the sea, which we feared might be rough, was calm enough for easy fueling.” After a presunrise takeoff of the attacking air fleet on the seventh, Fuchida set a flight course due south at 0615. “We flew through and over the thick clouds which were at 2,000 meters [6,562 feet].… But flying over the clouds we could not see the surface of the water, and, consequently, had no check on our drift.”97 From other sources we learn something about conditions before the sixth. Captain Genda Minoru, who planned the attack, and was aboard the flagship Akagi, told interrogators that during the passage to Hawaii the fleet “didn’t expect to meet any shipping, and fog and stormy weather would impair visibility conditions, anyway.”98 A prisoner of war told U.S. interrogators that the weather was closed in until the afternoon of the fifth.99 From interrogation of a carrier pilot U.S. intelligence learned that during the fleet’s passage, at least up to 2 December, “the weather was foggy part of the time.”100 Sadao Chigusa, chief ordnance officer of the destroyer Akigumo, recorded in his diary that “stormy weather” had attended the fleet’s passage as far as 5 December (Hawaii time).101
There is no report of weather conditions on the sixth as such that the writer has been able to uncover, but it is not unreasonable to assume that they generally conformed, if not to the stormy, to the cloudy conditions before the fifth and on the seventh. Any PBY patrolling the northern sector would have had to fly beneath the cloud bases, and it is problematic how much haze hampered visibility below those bases. If, instead of the PBY, a B-17 had been assigned to the northern sector on 6 December, its wider radius of visibility might have given it an edge in detecting ships below, but the B-17 would have had to fly, ponderously in its case, beneath the cloud bases. With the little observational weather evidence we have available from the period, though, on the other hand, with our general understanding today that meteorological conditions north of Oahu are usually marginal, particularly in winter, perhaps the most that one can say is that, if Kimmel had in fact ordered distant air reconnaissance over the sector north of Oahu, the flight crews may likely not have sighted the Japanese carriers; and that one may reasonably agree with what Martin and Bellinger concluded in their estimate of 31 August: namely, that in a dawn attack (certainly where the northern sector was concerned) there was “a high probability that [it] could be delivered as a complete surprise in spite of any patrols we might be using.”102
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If, as Kimmel argued, and, as he said, Washington plainly knew, he could not both conduct a distant air search and have his patrol planes ready in “maximum practicable number” to undertake their first wartime missions in the Marshalls raid, was there no other means he might have seized upon to post sentinels around his perimeter? There was, in fact, such a means, and it dated from the age of sail, when it acquired the name picket ship. Technologically inferior to aircraft, of course, in speed and coverage, and likely to be destroyed by the enemy it detected, the picket ship did have a justifiable use in modern times, which can be expressed in the maxim: in extremis extrema tenenda sunt.103 While Kimmel may not have thought he could spare his task force vessels for sentry duty, he and Bloch had other vessels at their disposal that could have been deployed for that duty, including submarines. Those other vessels sat low on the water, thus would have limited radius of vision, but they still had the practical potential of sighting by chance a carrier’s tall island on the horizon. Fleet-type submarines could cover 7,000 to 10,000 nautical square miles per day: with brackets on the periscope shears (supports) they could place eyes thirty-five feet above water. Even so, the small number of vessels and the marginal vision they provided meant that only a comparatively few sectors could be covered, such as the north and the south.
Kimmel had been urged to deploy small surface vessels to the northward and southward by Stark as early as 10 February. Warning him that “in view of the inadequacy of the Army defenses, the responsibility … must rest upon the fleet for its own protection while in Pearl Harbor,” Stark went on in the same communication to propose the following expedient:
It is noted that no provision is made in the Local Defense Force plans of the Fourteenth Naval District for the employment of vessels as a part of an aircraft warning net in the waters to the northward and southward of Oahu. It is suggested that in coordinating the plans of the Commander-in-Chief, U.S. Pacific Fleet, and the Commandant, Fourteenth Naval District, this matter be given consideration. It is possible that large sampans equipped with radio might prove useful for this purpose during the war.104
The Hawaiian “sampan” was a flat-bottomed skiff, built along oriental lines, propelled by a diesel engine, and, because of its sea-keeping capability, widely used on prolonged cruising in the Hawaiian fishery. Crewed by Hawaiian Japanese, the sampan fleet was based at Kewalo Basin, about twelve miles from Pearl Harbor. The vessel’s use proposed here as a naval picket boat was not as far-fetched as might be thought by modern readers. One has only to remember the Japanese use of small fishing vessels in a picket boat line positioned 600–700 nautical miles east of their home islands on 18 April 1942, the date of Lieutenant Colonel James H. Doolittle’s B-25 bombing raid on Tokyo and other Japanese cities. The U.S. Navy task force, including the carrier USS Hornet, from which the bombers were to be launched, was sighted by a picket boat while still 650 nautical miles from Japan. The task force twice changed course, but another outlier was encountered after each alteration. The pickets got off their sighting reports. It then became necessary to launch immediately, though the plan had been to launch at 500 miles distance. This meant both that the attack, scheduled to take place at night, had to be made during daylight and that the air crews, forced to fly 150 additional miles, risked not having enough fuel to make landing fields in China.105
On 21 December 1945, before the JCC, Admiral Turner testified as follows:
We informed—the Chief of Naval Operations informed—the Commander-in-Chief of the Pacific Fleet in at least three official communications during 1941 that it would be desirable to use ships to the northward and on one occasion to the southward of Hawaii for detecting approaching raiders, in addition to the use of airplanes, and we had endeavored to get small craft to send out and be on look-outs. One of these letters suggests the use of five sampans that had just been condemned [legally appropriated for public use under the right of eminent domain] by a court out there and the use of yachts which we were trying to get to them.106
Kimmel had still other craft that might have proved useful as pickets, and, together with the sampans, should have been numerous enough to guard sectors to the northward and southward, as recommended by Stark. These were five submarines, four old destroyers, four small minesweepers, three Coast Guard cutters, the gunboat USS Sacramento (PG-19), one net vessel, one gate vessel, two self-propelled oil lighters, and twelve tugs.107 Of the last-named Ingersoll wrote on 13 August to Kimmel that “should the fleet leave, [they] might be used for patrol purposes.”108 One is reminded of what Samuel Eliot Morison said about the Navy’s (Admiral King’s) costly delay in deploying a coastal picket patrol composed of small craft to detect German U-boats off the U.S. East Coast in 1942: “More of the Dunkirk spirit, ‘throw in everything you have,’ would not have been amiss.”109 When in the JCC hearings, on 21 December 1945, Kimmel’s picket boat assets were discussed by Senator Homer Ferguson (R., Mich.) and Admiral Turner, the following exchange took place:
Senator Ferguson: Why didn’t we use those then?
Admiral Turner: I do not know, sir.110
Kimmel’s comment on surface distant reconnaissance, made before the Army Board in 1944, was laconic: �
�The use of surface craft for distant reconnaissance against an air attack would have required so many ships that their use was considered entirely impracticable for this purpose.”111 The NCI in the same year concluded, somewhat moralistically: