Lieutenant Junior Grade was one of the top scoring aces among Imperial Japanese Navy Air Service (IJNAS) fighter pilots.Dr. Yasuho Izawa, 1993, Gekitsui Ō to Kūsen (Ace and Combat), Kōjinsha He entered the Imperial Navy in 1934 and completed pilot training in December 1936. His first combat occurred over China in early 1938. He emerged as one of the top aces of Imperial Japan during World War II, credited with at least 80 aerial victories, including 14 victories in China. Subsequently, he flew Zeros from the aircraft carrier Zuikaku from December 1941 to May 1942, including at the Battle of the Coral Sea. Iwamoto decorated his planes with victory markings of cherry blossom flowers, with a single or double blossom flower referring to a shot down enemy fighter or bomber aircraft respectively.
In late 1943, Iwamoto's air group was sent to Rabaul, New Britain, resulting in three months of air combat against Allied air raids.pp. 127–136, Ryūnosuke Kusaka, IJN Grand Fleetch. 9, Gregory Boyington, BAA BAA BLACK SHEEP The general attack to smash Rabaul fortress with all Allied air units continued 17 December 1943 – March 1944.
Subsequent assignments were Truk Atoll in the Carolines and the Philippines, being commissioned an ensign in October 1944. Following the evacuation of the Philippines, Iwamoto served in home defense and trained kamikaze pilots.
As a result of the Japanese use of the British naval practices, the IJNAS scoring system was based on the system the Royal Navy and the Royal Air Force (RAF) adopted from World War I until World War II. This system differed from the scoring system used by some other nations during World War II. Research by academics surnamed Izawa and Hata in 1971 estimated his score at about 80 or more than 87. In December 1993, Izawa wrote that Iwamoto was virtually the top ace of the IJNAS.pp. 171–268, Izawa, Hata, 1971, Nippon Kaigun Sentōki Tai, Kanto-sha; pp. 62–63, Izawa, 1993, Nippon Riku-Kaigun Ace Retsuden(IJAF and IJNAF Aces), Kōjinsha
As of mid-1944, there remained only two IJNAS fighter pilots who were credited with over 100 victories. Depending on various totals cited, Tetsuzō Iwamoto or Hiroyoshi Nishizawa was Japan's top ace. Iwamoto was known as the Chūtai leader (Flying Company, squadron of 8 to 16 fighters). Iwamoto was one of few survivors of the IJNAS from the early part of the Second World War. He fought over the Indian and the Pacific Ocean from north to south, and trained young pilots even in the last months of the war.p. 470, Saburo Abe, Zero Fighter Pilots Association, 2004, "My combat against Spitfires on VJ-day", ZeroSen, Kaku Tatakaeri!, Bunshun-Nesco, pp. 248–249, Toshio Hijikata, 2004, Kaigun Yobi-Gakusei Zero-Sen Kūsen-Ki (Air combat note of an IJNAF reserved student officer Zero fighter pilot), Kōjinsha Like many Japanese veterans, Iwamoto was reported to have fallen into depression after the war. His diary was found after his death, with claims of 202 Allied aircraft destroyed.
Early life Tetsuzo was the third son of the Iwamoto family. He was born on a border town, southern part of Karafuto 15 June 1916, later grew up in Sapporo, Hokkaidō, Japan. He enjoyed skiing in his elementary school days. When he lived in Sapporo, his father was a chief police officer.
When he was 13, his father retired and Tetsuzo moved with his family to his father's hometown, Masuda, Shimane Prefecture. He studied at the Prefectural Masuda Agricultural and Forestry High School. His favorite school subjects were mathematics and geometry; in these subjects, he always scored As on his school report.
He was an active and nimble boy. He joined a school club brass band as a trumpeter. Another hobby was growing plants and flowers. He helped local fishermen in the fishing season, going out to the sandy beach early in the morning and driving fish into the nets. He talked down to his teachers sometimes in discussions, which was very impolite for a school student in pre-war Japan. He was regarded as the most opinionated student in his school.
Starting military career
Iwamoto started his military career in 1934 after he graduated the school at 18. Following the advice from his parents to study while young, Tetsuzo left for a large city where he was supposed to take a college entrance examination. He, however, secretly applied for and passed the examination for acceptance as an Imperial Japanese naval airman 4th class, and was promoted to 3rd class 5 months later. His parents were very disappointed, for they became reliant upon Tetsuzo rather than his eldest brother, who was already studying at some university in a large city and would not return to Masuda.Mrs. Iwamoto's postscript within Zerosen Gekitsui-Oh(Zero fighter ace)
In 1936, when he was a naval mechanic 2nd class and a crewman on the light aircraft carrier Ryūjō, he studied hard and passed the difficult IJNAS exam, taken by thousands of applicants. He was enrolled in the class 34th Sōju-Renshūsei (Sōren means flight trainee program) for naval petty officers and sailors. He graduated as one of the select 26 young aviators of the class 34th Sōju-Renshūsei (flight trainee program) in December of that year.
On April 4, 1936, he was sent to Kasumigaura-Ku (Kasumigaura FR(AG)) as a probationer in the class 34th Sōju-Renshūsei (flight trainee program), then on April 28, formally joined Kasumigaura-Ku. While his training going on November 1, 1936, he was promoted to naval mechanic 1st class. Finally on December 26, he graduated 34th class of Sōju-Renshūsei, was promoted to airman 1st class (old rank name of pre-war Japan, equivalent to senior airman). During flight training school at the Tomobe branch of Kasumigaura-Ku (Kasumigaura FR(AG)), his fighter course instructor was the well-known Chitoshi Isozaki.
In December 1936. Iwamoto entered Saeki Kōkūtai (a Kōkūtai was a Naval Air Group, whether being based at land or on board a carrier) for 6 months of advanced training (termed extended education), finished and next entered Omura Kōkūtai on July 16, 1937. He had hard training there every day from senior pilots including Air Petty Officer 1st class Toshio Kuroiwa (rank grade was at that time), who was the IJNAS legendary dogfight master pilot. Tetsuzo Iwamoto (called Tetsu in short from his senior pilots) had to wait for his debut until February 10, 1938.
China front Tetsuzo's ability as a fighter pilot was recognized by all on his first air mission with the 13th Flying Group on February 25, 1938, over Nanchang, China.
After combat training, on February 10, 1938, Tetsuzō Iwamoto was led by his leader APO 1/C Toshio Kuroiwa, flying for two and a quarter hours over the China Sea from Omura Airbase at Kyūshū Japan to the airfield outside of Nanjing China.
His squadron on the Chinese frontline was the 13th Flying Group Fighter Squadron. This Flying Group was highly regarded and was famed as the Nango Fighter Squadron, named after its former squadron leader, Mochifumi Nango, who had shown considerable courage and conspicuous leadership.
Iwamoto's first experience of combat came on February 25, 1938, over Nanchang. His squadron's fighters escorted a group of Type 96 land-based attack aircraft. Chinese fighters attacked, and the squadron's leader Lieutenant Takuma was lost on this mission.
Iwamoto described his first combat experience in his notes. During the escort mission, his squadron was intercepted by sixteen I-15s and I-16s at an altitude of 5000 meters. Iwamoto claimed 4 victories (1 probable) in the combat. He secured his first victory by firing when within 50m of the enemy fighter. He first saw white smoke, then the enemy burned up and crashed. He was then at an altitude of 4000 m. When he looked back, there was an enemy fighter just behind him. He instantly made a Split S maneuver and narrowly escaped.
He got his second victory against an I-15. He saw it below him, turned and attacked from its 6 o'clock high. When it was hit, it climbed sharply and went spinning downward out of control and crashed into the ground. He kept his altitude of 4,000 m. He got an I-16 at the top of its roll in his gunsight and fired a burst, its engine burning and out of control; Tetsuzo lost sight of it before it crashed, and he reported this as probable. Another I-15 came down to him from 12 o'clock ahead. Both made a climb and were soon in a dogfight. The I-15 tried to break free of him and made a straight dive. That action made it easier for Tetsuzo to aim. He downed this I-15 on farmland near the airfield. He was flying at an altitude of 2000 m.
Above him, many enemy fighters were maneuvering. He found one of them coming down with landing gear down. He chased it to an altitude of 200 m and fired a burst. The I-16 was surprised and made a Split S maneuver, but crashed at a corner of the airfield. This was his 4th victory.
Anti-aircraft guns started firing heavily, and he found himself in an intense barrage of flak. Rushing to escape at full throttle with a number of enemy fighters behind him, he succeeded in returning safely from the battlefield. His leader Kuroiwa had already returned to the Wuhu airfield, Anhui China, waiting for his return. Kuroiwa scolded Tetsu severely for the rash attacks he made on the day.
The 13th Flying Group Fighter Squadron was merged with the 12th Fighter Squadron on March 22, 1938, where Type 96 carrier fighters for 1st Chutai had landing gear painted in red and were called Red legs squadron while 2nd Chutai had gear painted in blue and were called Blue legs squadron.
Iwamoto was awarded the citation of flying group Cmdr Tsukahara for his extreme courage and conspicuous gallantry in action above and beyond the call of duty as a fighter pilot against intense Chinese air force on April 29, 1938. He made 82 sorties and 14 victories credited in the China front. Tetsuzō Iwamoto became the top IJNAS ace. His activities subsequently earned him Order of the Golden Kite – 5th class recommendation in 1940.
In September 1938, 22-year-old Iwamoto was ordered back to Japan, where he became a member of the Saiki Air Group and appointed to a training staff.
His flight log Flying Technique: Class-A of IJNAS Flight hours: over 8,000 hrs in March 1944 (net hours, not tripled as with a US single-seated fighter pilot. It was very unusual among IJNAS,IJNAS: Imperial Japanese Navy Air Service IJAASIJAAS: Imperial Japanese Army Air Service fighter pilots, although it was usual over 10,000 flying hours among the multi-seated aircraft IJNAS, IJAAS veteran pilots.) Oceanic Transition: possible, navigating and leading his fighter chutai (without Radar) Instrument Flight: possible Night Flight: possible Single-seat Fighter reconnaissance and attack mission across night ocean: possible Night landing: possible with simple approach lighting system Night carrier landing: possible with approach path indicator lights
Only experienced fighter pilots in the IJNAS could execute instrument flight with their single-seat fighter aircraft on combat missions; few IJNAS officer pilots could fly on instruments.
Tactics Single to single dogfight tactic – from losing to winning p. 127, 141, 305 Tetsuzō Iwamoto, 1973. Zero-sen Gekitsui-Oh Quick roll (Roll Senpō) (up and down quick roll tactic, skidding sideway (sudden decelerate) within 1/2 quick roll to forward the opponent aircraft on one's tail and get tail shot position of it. Cmdr Takeo Shibata promoted, his men developed and taught him.Roll Senpō: p. 469, Saburo Abe, Zero Fighter Pilots Association, 2004. ZeroSen, Kaku Tatakaeri!) Corkscrew loop (Hineri-Komi Senpō) (short-cut or twist-in loop tactic, skidding loop. Lieutenant Isamu Mochizuki's special, Section leader and Warrant Officer Toshio Kuroiwa trained him.WO Kuroiwa was the section leader when young Iwamoto first went to the China front 1938. Lt. JG Mochizuki was his chutai leader in 281 FR(AG) March 1943 – October 1943.) Yo-yo turn (Suichoku-Senkai Kasoku Senpō)