Attack on Pearl Harbor (41 page)

Aircraft combat losses can also be estimated using loss rates predicted in the Naval War College Maneuver Rules. Losses are calculated as a percentage of the attacking and defending numbers. Fighters were allowed two engagements per sortie.

For the first wave, 43 US fighters would be engaged by 43 Japanese A6M2 Zeros, while the remaining 63 US fighters went for the bombers. Losses would total 34 US fighters and 38 Japanese planes, 12 of them fighters and 26 bombers.

The NWC air–to-air combat formulas remained unchanged between 1941 and 1945. In the 1946 rules, the equations for air-to-air losses were revised to take into account wartime experience. Using these rules 8 US fighters and 50 Japanese aircraft, 12 fighters and 38 bombers, would be shot down.

The NWC rules allowed the surviving US fighters to return to their bases to be re-armed and re-fueled and sent up again. The P-40s were based at Wheeler airfield, about 8 miles northwest of Pearl Harbor, so flight time would be short. The NWC rules specified the required ground turnaround time. 60 fighters would be aloft to engage the second wave, 40 with two engagements and 20 with time for one. This likely overestimated the turnaround time at Wheeler, where most aircraft had individual ground crews, revetments, and service equipment. Aircraft could also be serviced by outlying airfields, reducing the queue at Wheeler.

The Japanese second wave was to consist of 33 A6M2 Zero fighters, with bombers bringing the total up to 167 aircraft. Using the same assumptions as before, the 1941 NWC rules would result in 12 US fighters and 16 Japanese aircraft (nine fighters and seven bombers) lost. The 1946 rules give six US fighters lost, with nineteen Japanese (nine fighters and ten bombers) shot down.

The NWC rules have weaknesses.

The NWC approach was designed as a “quick and easy” way to inject air combat losses into a wargame that was being executed with judges performing all the calculations with pencil and paper. It was designed to give expected value, approximate results on an operational level. It reflected the informed expectations of aviators during the interwar period; after the war, it was changed to reflect combat experience. The calculations provide a reasonable first-order estimate of losses in an air-to-air action.

The scenario calculated above does not include the 15 USMC F4F Wildcat fighters at Ewa Field, 14 of which were operational. If the AAC fighters engaged the first wave, Ewa would likely not have been strafed and these F4F Wildcats might have been able to join the battle. The Marines could have contributed an additional 16% to Japanese losses.

Full Army AA Alert

The Army conducted a full-scale seven-day exercise just prior to the attack. All AA guns were deployed and supplied with live ammunition. But, as related by a Provost Sergeant assigned to the defense of Bellows Airfield, “On Saturday, 6 December, we were told to take down all arms and lock [them] in [the] Armory and take our passes to Honolulu.”
³⁶

The AA unit assigned to protect Ford Island was quartered 15 miles away at Camp Malakole. Daily the guns were trucked to Pearl Harbor, complete with ammunition. They arrived at Ford Island by ferry. 7 December was the first Sunday in months this task was not performed.
³⁷

If the Japanese had attacked during the Alert, 19 mobile 3-inch batteries totaling 76 guns would have been added to the defenses.
³⁸
They could have accounted for an additional 12 to 48 aircraft destroyed. The combined Army three-inch AA batteries could have destroyed 18 to 78 aircraft.

Each of the airfields had an assortment of 20mm, .50-cal, and .30-cal machine guns available for perimeter and overhead defense, along with small arms. It is very difficult to make an estimate of enemy losses from these weapons, as it would require knowing how many aircraft came within range. These short-range weapons may have shot down as many as 4 aircraft in the attack. The contribution of these weapons can be included by adding the 4 historical kills to the estimates.

All the Defenses Combined

Adding together the potential Japanese losses from all sources gives the following low and high-end estimates.

This is a first-order estimate only. Calculating losses independently and then adding them will tend to overestimate losses—more aircraft shot down by fighters would mean fewer targets for the AA guns, and so on. The point of the calculation is to approximate the magnitude of Japanese losses to see if the American defenses were “inadequate” as claimed in many history books.

If the American defenses had been active as they should have been, the Japanese would have suffered stunning losses, and the damage to the Pacific Fleet would have been considerably less than what was actually experienced.

Losses most likely would have been on the order of 50% of the attacking force. This is in line with aircraft losses in the 1942 and 1943 aircraft vs. ship battles. At the Battle of the Coral Sea, the Japanese lost 30% of their aircraft, and the carriers
Shokaku
and
Zuikaku
were put out of the war for approximately a year working up replacement aircrews. At Midway,
Hiryu
launched two strikes against the US carriers that suffered 63% losses. The US torpedo bombers at Midway took 86% losses. On 20 February 1942,
Lexington
was attacked by 18 land-based twin-engine Betty bombers and 16 were shot down, for 89% losses. On 12 November 1942, 21 Betty bombers attacked an American task force off Guadalcanal and suffered 95% losses. The Japanese aircraft losses at Pearl Harbor could have been equally horrific.

The following table shows the Japanese fleet carriers and their active aircraft capacity. If the Japanese took any significant losses from their air groups in the Pearl Harbor attack, it is likely that they would consolidate their air groups, stripping some carriers to keep the others operational. The table shows what carriers might be forced out of service due to lack of aircrew:

In other words, the Japanese fleet would have had one-third to two-thirds of their fleet carrier force placed out of action, and might have had only two carriers with their smallest aircraft capacity remaining in service, with the others out until late 1942.

Japanese aircraft were also in short supply. In the above scenario an additional 50 to 75 aircraft might have been damaged beyond repair—in the actual battle 20 damaged aircraft were jettisoned as unserviceable. With those additional aircraft losses another carrier would have been out of service for some months awaiting replacement aircraft.

The Japanese were short on manufacturing capacity for naval aircraft, and had no reserve A6M Zeros. Two Japanese light carriers were not fitted with combat air groups in the early months of the war due to lack of aircraft and aircrew. Two active light carriers,
Hosho
and
Ryujo
, started the war with obsolescent A5M Claude fighters, aircraft with fixed landing gear, and continued to carry these aircraft for months.

Conclusion

If the Japanese had attacked just a few days earlier, while the Army defenses were in Alert 2, they would have lost enough aircraft and aviators to put one-third to two-thirds of their fleet carriers out of service. The Japanese could have conceivably lost more than half of their total stock of experienced carrier-qualified aviators. This would have had a significant effect on the course of the war in the Pacific.

A mass of folklore has developed concerning the attack on Pearl Harbor. Stories, assumptions, unverified witness reports and other tales have been passed from source to source with little critical examination.

1)
Japanese “Superpilots”

Before the war most Westerners had little respect for Japanese aviators. Among many odd beliefs, Americans thought that the Japanese had defective vision (stereotypically, the Japanese in pre-war movies characteristically wore glasses, especially the bad guys), and a genetic predisposition towards defective balance, making them poor pilots. Many believed Japanese aviators were not capable of executing so complex a task as an attack on Pearl Harbor.
¹

From the depths of contempt, after Pearl Harbor the Japanese aviators were hoisted to the status of demigods. Reinforced by their successes in the first six months of the war, legends have developed around the pre-war trained core of Japanese carrier flyers, that they were super-aviators, masters of aerobatics, consummate warriors, and all seasoned veterans of the China Wars. One historian claimed that “many” of the Pearl Harbor attackers had “hundreds of hours of combat flying experience.”
²
“Japanese aviation abilities, heavily downplayed by the United States and Great Britain before the war, were suddenly accorded almost mystical reverence.”
³

Some of the perpetrators of this myth have used statistics to bolster their claims. “The average flight time of a US Navy pilot in December 1941 was 305 hours against an average of 700 in the entire Japanese Navy and up to 2,000 in the Pearl Harbor strike force,”
⁴
intoned one source.

The aviators of the
Kido Butai
, the carriers of the Mobile Striking Force, averaged 800 hours at the time of Pearl Harbor. To place this in context, Japanese pilots received about 300 hours in basic training and 200 hours in advanced training before being assigned to a carrier. This took about two years, a year of ground school followed by a year of flight training. Even then, a pilot reporting to an aircraft carrier was not an “all-up round” ready for combat. Peattie found that “Japanese naval aviation, unlike the other branches of the service, mainly used its operational units as training facilities rather than training its personnel in specialized schools.”
⁵
Aviators newly assigned to an operational carrier needed to qualify in their front-line aircraft, learn to land on a carrier, fly in formation, launch and marshal, and fight.

A “large-scale reshuffling” of the air groups occurred in early September 1941,
⁶
two months before the departure of the ships for the Pearl Harbor operation. Large numbers of junior aviators were introduced into the air groups. Among the critical torpedo bomber aircrews, many young, green fliers were initially assigned to the carrier groups from August throughout September. It was four to six weeks before the new arrivals completed their basic carrier qualifications.
⁷
This turnover was normal, similar to the spate of transfers and promotions that any large military organization goes through as senior people are transferred to training or administrative or command jobs, replaced by new junior personnel. In the memory of one Japanese aviator, “Usually people spent only one year on a carrier, because it was physically exhausting.”
⁸

As a result:

In September 1942 there were many new pilots (“nuggets” in modern US Navy slang) fresh to the Japanese carriers. There were also new ships to be manned, as escort carrier
Kasuga Maru
joined in September and fleet carriers
Zuikaku
and
Shokaku
were completed in October of 1941. This added an additional capacity of 171 carrier aircraft, up from 351, or a one-third increase.
¹⁰

Ensign Honma Hideo, a B5N Kate pilot assigned to
Zuikaku
, relates:

Ensign Honma was 19 years old and one of the more experienced aviators on his ship. The two others in his crew were 16 or 17 years old. The aged Honma “felt they were still kids.”

Genda, in a postwar analysis of the Pearl Harbor attack, admits that the “airplane units of the 5th Carrier Division [new carriers
Zuikaku
and
Shokaku
] could not keep up with the 1st and 2nd even to the end because the units were newly organized and were not trained sufficiently.”
¹²

One Japanese senior officer mentioned that when these ships joined the fleet skilled A6M Zero pilots were hard to find. Airmen were transferred from the light carriers
Ryuji
and
Shoho
,
¹³
while others were pulled from instructor duty and experimentation duty with the Yokosuka Air Group.
¹⁴
This provoked opposition from the Navy Ministry’s Aeronautical Department and the Personnel Bureau. Yamamoto was risking his “seed corn;” if these experienced aircrew were lost, the lack of trained and experienced instructors would make it all the more difficult to reconstitute the air groups.

The converted former luxury liner
Kasuga Maru
joined the fleet as an escort carrier [later named
Taiyo
] three months before the Pearl Harbor attack. She was fitted for an aircraft complement of 27—nine A6M Zero fighters (with 2 spares) and 15 B5N Kate carrier attack bombers (with one spare). However, there were insufficient airmen to make up her air group,
¹⁵
and so she was classified as an auxiliary and relegated to duties as an aircraft ferry. She was reclassified as a warship on 31 August 1942, but performed ferrying duties for a considerable period thereafter, only participating in one operation in a combat role.

All the aircrews began an intensive period of training for the attack. For the B5N Kate carrier attack bombers assigned to carry torpedoes, it meant three sorties a day for many weeks. For the dive-bombers, Abe Zenji, commander of a group of nine dive-bombers on carrier
Akagi
, testified, “These practice missions continued over and over, on some occasions for five hours or more.” According to the Japanese Navy’s post-operation study, “… there had been many fliers who were not familiar with landing-on-carriers practice…. Most of the training time for young fliers was therefore used in landing-on-carriers practice.”
¹⁶
Abe recalled that among the dive-bombers, “Accidents were common and some aircraft dived into the sea because the pilots were unable to withstand the G stresses in the face of the exhaustion brought on by the severe training schedule… we faced death every day.”
¹⁷

In other words, a large portion of the air groups were nuggets, and much of their training was devoted to fundamental flying skills. Weapon delivery practice came next. Integrated air group training, or rehearsals of the actual attack, was last, and never satisfactorily accomplished. There was no inter-type training, so the bombers never learned how to work with the fighters, and vice versa. This reflected the Japanese’s “stove-pipe” attitude towards aircraft missions. Each type was independent with little cooperation envisioned.

Under intensive training the aviators would accumulate over 100 hours of flight time per month—Ensign Maeda Takeshi’s flight log recorded 128 hours in October. This would have brought nuggets right out of flight school up to 700 to 800 hours total by November 1941. The sprinkling of second tour aircrew and leaders, most with over 1,500 hours, would bring the average flight hours up to the stated 800 hours average. So, the intimation by some historians that the Japanese aviators having an average of 800 hours denoted an unusually experienced and well-trained force is not correct. The statements in many histories intimating that the Japanese sent to Pearl Harbor a flock of super-pilots, seasoned veterans of the war in China, is a myth. This was a normal contingent of aviators, the majority in their first tour on a carrier. The major advantage was in the 26 flight leaders, of which a few had seen limited action—most of the naval aviators that saw action in China were land-based medium bomber aircrews, not carrier aviators. Only a few strikes, numbering in the single digits, were launched from carriers. The idea that “many” of the Japanese aviators had “hundreds of hours of combat experience” is wrong.

American pilots during the interwar period were given 500 hours before being sent to their squadron for advanced training. Just before the war began, to accommodate the rapid expansion of the fleet, training hours were cut back. Some pilots joined combat units with only 250 hours. They began arriving in the fleet in the autumn of 1942, well after Pearl Harbor.

“The [US] pilots in the service before World War II were an ‘elite’ group,” according to a pilot who joined his first squadron in September of 1942.
¹⁸
The Japanese training program, in terms of flight hours, was not superior to that given to American pilots during the interwar years. In contrast, in 1939 Canadian recruits were given 100 hours of flight training before receiving their wings and being transferred to combat duty in Britain.
¹⁹

The Japanese sent to Pearl Harbor airmen trained to typical interwar standards. Their primary advantage over their American opponents was a period of intensive training just prior to the operation, which got the newer airmen (including most of the aircrew on the two newly-commissioned carriers) up to the same operational level as new American pilots that were sent to operational units. The Japanese aviators that attacked Pearl Harbor were not the super-pilots that folklore would have us believe, particularly the A6M Zero fighter pilots, the subjects of particular veneration in the popular mind. Understanding this, it is easier to comprehend how the American fighter pilots at Pearl Harbor were able to rack up a kill ratio of between four: one to six: one, and lose only 15% of their numbers. When it came to their primary mission, to sweep the skies of American fighter opposition, the Japanese fighters failed. They shot down two fighters that were barely aloft after their takeoff run, but of the fourteen fighters that attained combat altitude they only disposed of two, a far cry from the Japanese fighter performances in China where the A6M Zero would typically shoot down 20 of 23 Chinese fighters. The Japanese fighter pilots were not as good as in China, and the American fighter pilots and their fighters outclassed what the Japanese had previously seen.

The quality of
Kido Butai’s
fighter pilots would improve over the first six months of 1942, where they had the opportunity to gain more flying hours in attacks that were almost unopposed. They reached peak efficiency during the raid into the Indian Ocean and the attack on Darwin. Even so, they were not overwhelmingly dominant in the Battle of the Coral Sea, and their lack of flight disciple and command and control deficiencies directly led to the annihilation of the carrier striking force at Midway.

The Japanese training standards eroded dramatically during the war. The aviators at Pearl Harbor were much better than later flight school graduates, another contrast that accentuated their relative prowess.

A noteworthy point was that the Japanese planners decided upon the number of bombers to carry torpedoes before they resolved the technical problems of launching torpedoes in shallow waters, and before any reasonable percentage of hits could be estimated. The number of B5N Kate bombers allocated to level bombing attacks against the battleline was also determined in advance, when level bombing percentages were so abysmal that Genda had “almost given up on horizontal bombing.”
²⁰

An alternate approach would have been to train all of the aircrews in both forms of attack, and then allocate weapons after the technical issues had been resolved and after a better estimate of hits with each weapon could be determined. This would have allowed the planners the flexibility to change weapon-target pairings at the last minute based on such factors as the accuracy displayed in training or the latest information on the composition of the American fleet in harbor. Instead, the weapons-target pairings and aircraft assignments were made months in advance, and not changed. One reason for this was the training required to get the aviators sufficiently skilled in just one form of attack. They were not sufficiently skilled to swap from one role to another. This limited the flexibility of the planners.

Shokaku
and
Zuikaku
were operational just weeks before the Pearl Harbor raid.
Zuikaku
and
Shokaku
’s B5N Kates were all allocated to level bombing attacks against airfields, targets demanding less accuracy than fleet targets.