Midway - Chapter 7 of Radar and the Fighter Directors

By David L. Boslaugh, Capt USN, Retired

A Plan to Annihilate the U.S. Pacific Fleet

In mid-May 1942 the U.S. Navy codebreakers scored again. They had found that the Japanese planned to strike Midway Island and U.S. bases in the Aleutian Islands in early June with a huge battle force. It would be made up of virtually every combatant ship in the Japanese Navy, 165 combatants in all. Planes from four fleet carriers: Soryu, Kaga, Akagi, and Hiryu with supporting forces were to destroy the defenses on Midway early on 4 June in preparation for an amphibious landing of 51,000 men the next day. A Northern Area Force with two light carriers and other surface combatants were to make a diversionary attack on the Aleutians with the goal of capturing the islands of Kiska and Attu. Another primary goal of the battle force was to lure what was left of the U.S. Pacific Fleet into a decisive sea battle to finish what they had not accomplished at Pearl Harbor. Admiral Yamamoto, the Combined Fleet commander, would lie off a few hundred miles in his flagship Yamato, the largest warship in existence. He was sure U.S. carriers would deploy to rescue Midway, and accompanied by six other battleships, he would move in to eliminate any remaining American ships after the expected carrier battle. Yamamoto was convinced that the carrier Yorktown as well as Lexington had gone down in the Coral Sea, and, with only two U.S. carriers left in the Pacific, he was safe in splitting his carrier force into two groups.

In preparation, Admiral Nimitz strengthened the Marine garrison on Midway, and had additional airplanes flown in to supplement the twenty-one Brewster Buffalo Fighters and sixteen Vought Vindicator dive bombers already on the island. The additional aircraft sent to Midway included seven Wildcat fighters, eighteen Douglas Dauntless dive bombers, four Army Air Corps B-26 torpedo-carrying Marauder medium bombers, and six Grumman TBF Avenger torpedo bombers. Also available were eighteen Boeing B-17 long range heavy bombers, based on Oahu, and thirty-two PBY Catalina patrol planes, based on Midway. The Grumman Avengers were fresh from the factory, and this would be their combat debut. Nimitz had the carrier Yorktown rushed through battle repairs in three days at Pearl Harbor Naval Shipyard, and Task Force 16, comprised of the carriers Hornet and Enterprise, with supporting combatants, was recalled from patrol and readied. With Yorktown back in the battle, Nimitz had three carriers which, all together, could carry about 250 planes; which was about the same as the air complement of the four carriers under Admiral Nagumo. Vice Admiral Halsey, who normally would have commanded the TF 16, was hospitalized with a skin rash, so Nimitz assigned the job to Rear Admiral Raymond A. Spruance. Yorktown, and supporting ships, formed Task Force 17 under command of Rear Admiral Frank J. Fletcher, who would act as commander of the combined task forces. [15, pp.62-68]

On 3 June, the admiral’s staffs aboard the two flagships, Yorktown and Enterprise agreed on how fighter direction for the coming battle would be handled. The battle plan called for keeping the two tasks forces about twenty-five miles apart. This would keep them close enough for mutual fighter protection, but separated enough that it would be hard for an enemy snooper to sight both forces at the same time. It was agreed that Spruance’s staff communications officer on Enterprise, LCDR Leonard Dow, would direct the fighters of all three carriers, with the stipulation that if TF 17 had to operate separately, LCDR Oscar Pederson, CAPT Buckmaster’s air group commander and FDO, would control Yorktown’s fighters. So that both FDOs would know the radio call signs of all pilots, fighter organization charts were exchanged, and both FDOs would use the same radio frequency. They also exchanged fighter direction terminology lists and found there were a few inconsistencies. Each carrier was given a FD call sign, with Enterprise being “Red Base”, Hornet “Blue Base”, and Yorktown “Scarlet Base.” Likewise, the fighters from each carrier would use their carrier’s color followed by their number in the squadron as their identification. All Enterprise Wildcats were IFF equipped, and more than half of Hornet’s fighters were so equipped, but barely half of Yorktown's fighters had IFF, so Yorktown’s air officer rearranged squadron assignments so that each fighter section would have one IFF equipped aircraft. Hardly any of the attack airplanes had IFF, so the FDOs knew they would be using a lot of CAP resources just checking out unidentified friendlies. The admirals also agreed that the prime responsibility of the fighters would be carrier protection, even at the expense of fighter escort for strike groups. [33, pp.323-324]

Many Planes, Heading Midway

In the early morning of 4 June, the American task forces were nearing a location 200 miles north of Midway, and Nagumo’s four carriers were almost at their launch point some 240 miles northwest of the island. At 0430 Nagumo launched his strike of seventy-two bombers, protected by thirty-six Zero fighters. At 0534 a patrolling PBY sighted two of the Japanese carriers and radioed their location, course and speed. A few minutes after that another PBY ran across Nagumo’s attacking aircraft and radioed, “Many planes, heading Midway—bearing three two zero—two five zero miles.” A few minutes later, a Midway-based SCR-270 radar, a close cousin of the CXAM, detected the raid. Alerted, the planes defending Midway took to the air; the fighters would try to stop the incoming raiders, and the bombers would work over the Japanese carriers. The Brewster Buffalos were no match for the protecting Zeros and there were not enough Wildcats. Seventeen of the twenty-eight American fighters were shot down and seven damaged for the loss of a few Japanese bombers. Only one of the new Avengers survived, and two of the torpedo armed B-26 bombers were shot down. No scores were made on the Japanese carriers. The Japanese bombers worked over island defenses for thirty minutes, but were not satisfied with the destruction. The air commander decided a return visit was needed, and ADM Nagumo directed that the returning strike force be refueled and rearmed for a return visit to Midway. At 0500 the Japanese heavy cruiser Tone had launched an Aichi E13A1 reconnaissance float plane, designated Tone No. 4, to search out 300 miles on 100 degrees and then to turn north for sixty miles, and then return to the cruiser. At 0728 the plane radioed a sighting report of ten enemy ships 240 miles north of Midway. Course and speed were given, but no mention made of aircraft carriers. At 0745 Admiral Nagumo was given the sighting report, which caused him to cancel the land attack and start rearming the attack planes with armor piercing bombs to go after the enemy surface force which he rated higher in priority than a second strike on Midway. [15, p.68] [9, p.243] [32, pp.30-31] [33, p.337]

Aboard Yorktown, ADM Fletcher heard the 0534 contact report. Yorktown had most of her SBDs in the air looking for the Japanese main force, so Fletcher directed ADM Spruance to have Hornet and Enterprise proceed toward the Japanese carriers. By 0745 Fletcher was close enough to the calculated position of the Japanese carriers to begin launching a strike. It would be an all-out effort. In the hurry of launching such a large force, the fighters who were supposed to protect the squadron of Devastator torpedo bombers from Enterprise, instead took station on Devastators from Hornet, leaving the former squadron without fighter protection. At 0815 Enterprise CXAM operators found a contact at thirty miles on bearing 185 degrees. It was Tone’s Number 4 float plane still looking for the task force. Task force FDO, LCDR Dow, broke fighter frequency radio silence to direct Red 17 section out on heading 170 degrees to check the bogey at low altitude. The terminology he used to designate heading was “Arrow”, and it meant pilots were supposed to mentally convert from true bearings to magnetic, for their compasses were magnetic. In the Midway area, this correction could be as great as twenty degrees. Conversely, LCDR Pederson, Yorktown FDO, used the term “Vector”, meaning magnetic bearings. This would cause some confusion in the forthcoming air battles. Because of low altitude cloud cover, Red 17 did not spot the float plane, and Tone No. 4 was able to get off another report saying the formation did indeed include one carrier. Fighter director Dow was still trying to destroy the annoying and dangerous snooper and at 0836 sent four more Wildcats out to search, but to no avail because the float plane was headed back to Tone. At 0844 he recalled the fighters. A few minutes later Enterprise’s CXAM showed another bogey to the north, and Dow this time sent out Scarlet 19 section for the intercept on what proved to be a friendly. [15, pp.68-72] [33, pp.337-339]

The Grumman TBF Avenger torpedo bomber first saw active service in June 1942 as a replacement for the obsolete Douglas TBD Devastator. It had an internal bomb bay that could hold one Mark 13 torpedo, or the equivalent weight of bombs. Crew was: pilot, rear facing dorsal turret (50 caliber) gunner, and a radioman/bombardier who also manned a ventral mounted 30 caliber machine gun. The plane also had one forward firing, nose mounted 50 caliber machine gun; later changed to two wing mounted guns. National Museum of Naval Aviation No. 1996.253.1299

At 0830 ADM Fletcher was able to start launching the air group from Yorktown. The two air groups did not know that Nagumo had changed his formation course, and they searched fruitlessly in the wrong area until some of the Wildcats ran so low on fuel they had to ditch, and the Hornet Dauntless dive bombers had to head back to their carrier or to Midway. Only the Enterprise dive bombers and the longer range Devastator torpedo bombers continued on, the Hornet bombers also having lost their fighter cover in the clouds. By 0920 Yorktown had separated so far from Task Force 16 that mutual fighter defense by one FDO was no longer possible, and LCDR Pederson took over directing Yorktown CAP, although, as air group commander, he would have much preferred leading the strike. At 0920, Hornet’s Devastator torpedo planes found the Japanese carriers and pressed an attack, but all fifteen were brought down by defending Zeros before they could get to launch range. Fifteen minutes later the unescorted Enterprise Devastators found the target and ten of the fourteen were shot down with no scores on the carriers. Yorktown’s torpedo planes, also without fighter cover, found the Japanese formation at 1000, but it was a repeat of the two earlier disasters. No scores on the carriers, and ten out of seventeen were brought down by the Zeros. [15, pp.68-72]

Akagi, Kaga, and Soryu Mortally Wounded

By 1005, the thirty-three Enterprise Dauntlesses were running critically low on fuel when they spotted the Japanese carrier formation. They split into two groups, one aiming for Kaga and the other for Akagi. Although the Japanese battleships were fitted with radar, their carriers had none, and they had no advance warning of the incoming dive bombers, and no time to prepare. This time the protective Zeros were either out chasing withdrawing airplanes, or had landed to refuel and rearm. Two bombs ripped through Akagi’s flight deck setting parked aircraft on fire and detonating bombs intended for rearming planes in the hangar deck. Akagi was abandoned at 1047. Kaga absorbed four 1,000-pound bombs that ignited a number of secondary explosions. At 1025, Yorktown's thirteen dive bombers took on Soryu, who suffered three bomb hits, and in twenty minutes was ablaze from one end to the other. Aboard Hiryu, which was standing off some miles to the north and under the AA protection of a force of battleships, cruisers, and destroyers, Admiral Yamaguchi could see three smoke plumes rising to the south. At 1058 he ordered Hiryu to mount an immediate counter strike of eighteen dive bombers and six fighters. They managed to find and follow some of Yorktown’s Dauntlesses heading back to their carrier. At about 1150, Yorktown's CXAM operator picked up the attackers at thirty-two miles, bearing 225 degrees; following the returning strike force. [5, pp.189-190] [9, p.144]

Yorktown Under Fire

LCDR Pederson sent out four Wildcats to intercept the raid, but by the time they received their vectors, the raid was in to twenty-five miles. Upon receiving their Tallyho report, he vectored out Yorktown’s remaining CAP and requested enough of the Enterprise and Hornet CAP to have nineteen Wildcats intercepting the twenty-four incoming Japanese planes. Pederson warned the returning Dauntless dive bombers to stand clear. The defending fighters did not make their interception until the raid was in to fifteen-to-twenty miles from Yorktown, and in spite of a vigorous fighter and AA defense, eight of the Aichi D3A dive bombers managed to make runs on Yorktown, and scored three hits. One bomb penetrated near the forward magazine, one blew up a portion of the flight deck, and one proceeded down the smoke stack and exploded in the boiler rooms, extinguishing the fires in all but one of the six boilers. The ships hull was still intact but she could only make six knots for a number of hours until four more boilers were relighted, enabling her to come up to 20 knots. [15, p.75] [11, p.21]

In one other small but exciting drama at 1340, Enterprise FDO, LCDR Dow, was advised of a new bogey bearing 180 degrees at range forty-five miles. A detection at this range meant it was at fairly high altitude. Dow vectored out Red 26 Section to intercept, and in twenty minutes they were on top of a Japanese float plane. It turned out to be scouting plane No. 5 from the heavy cruiser Chikuma, and its crew had been shadowing the American task forces for three and one half hours. The plane did not try to run away, and turned to face its pursuers, but did not last long. The episode did show that the CXAM could very precisely direct fighters to a target at long distance. A few minutes later Dow had another interesting experience brought on by transmissions on the fighter net to the effect that Hornet’s “Blue” fighters were getting low on fuel. Suddenly on the net came a transmission in very good, no accent, English, “All Blue patrols return for juice.” Dow quickly warned his fighters to not let the bastards deceive them. The incident did underscore the need for higher frequency, line of sight, radios so that the enemy could not listen in to their transmissions at long distances. In any event such attempts at deception would probably not work because the pilots well recognized the FDO’s voices. [33, pp.395-396]

An Aichi D3A1 ‘Val’ dive bomber from the carrier Akagi. A 1936 design with fixed landing gear, and a top speed of only 242 mph, the Val was considered obsolete by 1942. Regardless of that, they did considerable damage at Pearl Harbor, and to Lexington and Yorktown. They were armed with two fixed forward firing machine guns, one flexible rear firing, and could carry up to 810 pounds of bombs. Imperial Japanese Navy photo, Source: Warbirds Site http://www.ijnafpics.com

Admiral Yamaguchi had not yet used Hiryu’s torpedo squadron, and next ordered a strike on the American carriers by ten torpedo laden Nakajima B5Ns, escorted by six Zero fighters. Again they found Yorktown, whose CXAM radar at about 1430 detected them at forty-five miles range. Two minutes after detection LCDR Pederson sent out four Wildcats stacked at 15,000 to 18,000 feet altitude, and two more at lower altitude. The four high CAP passed over the raid without seeing them, and Pederson had to radio them “Return buster, you have passed them.” The lower two tallyhoed. The Wildcats and Yorktown’s AA fire brought down half of the torpedo planes, but the remaining five launched their weapons, and two found the ship. The torpedo strike knocked all of Yorktown’s generators off the line, so Pederson’s CXAM and fighter direction radio were no longer working. On Enterprise, LCDR Dow assumed overall task force fighter direction at 1444, and began sorting out fighters from three different carriers and retrieving those low on fuel. Again the stricken Yorktown came to a stop, this time with her rudder jammed and a twenty-six degree list. CAPT Buckmaster, concerned that the ship might capsize, had all but a skeleton crew of damage control personnel abandon ship to be picked up by escorting destroyers. [5, p.192] [11, p.21] [32, p.32] [33, p.399, p.410]

On board Enterprise at 1600, FDO LCDR Dow had twenty-seven CAP Wildcats in the air, and had them busy checking out bogies. One of the investigating Wildcats almost flushed the pesky Tone No. 4 float plane, but it was able to hide in a cloud bank just in time. Tone No. 3, an open cockpit, single-float Nakajima E8N2 biplane, did not fare as well. At 1615, Dow’s radar operator detected a contact bearing 290 degrees at range twenty miles, apparently snooping around Yorktown. He vectored four Wildcats out to investigate, and a few minutes later added two more to the intercept, thinking it might be a strike group. What they found, however, was one antiquated biplane with a single large float. As many as six Wildcats ganged up on the snooper who, in spite of the large float, turned out to be very nimble and evaded the fighters as they made four passes. He might have eventually gotten into protecting clouds, but made the mistake of trying to make a run on one of the Grummans whose guns had jammed. This necessitated his holding steady for a number of seconds which allowed two of the other fighters to flame the biplane. [33, pp.213-214]

The Nakajima B5N carrier-based attack bomber could carry one Type 91 torpedo or 1,760 pounds of bombs. It had a flexible rear mounted machine gun, and some models had two forward firing machine guns in the wings. It was crewed by a pilot, a navigator/bombardier/observer, and a radio operator/gunner. Government of Japan photo, Source: Warbirds site http://www.ijnafpics.com

Hiryu Goes Down

At the same time that Japanese torpedoes were hitting Yorktown, Enterprise’s Scouting Squadron Six found Hiryu. Twenty-five Dauntless dive bombers rose from Enterprise, and sixteen from Hornet, and by 1600 they were on the way. When Enterprise’s flight leader saw Hiryu about thirty miles to the west, he took the time to maneuver his dive bombers to the southwest of their target at 19,000 feet so that they would approach up sun. The tactic worked. Six Zero fighters were orbiting above Hiryu, but they did not see Enterprise’s planes until they were in their dives. By tight turns Hiryu avoided bombs from the first wave. The ship was not so fortunate with Hornet’s dive bombers. Bomb explosions rippled along the flight deck and the ships own exploding ordnance and aircraft fuel tanks fed the inferno. The four Japanese carriers burned throughout the night and Soryu and Kaga sank early in the morning on the fifth. Akagi and Hiryu finally had to be put under by torpedoes from Japanese destroyers later in the morning. Yorktown was still afloat and put under tow to return to Pearl Harbor, but her luck ran out when she was torpedoed by a Japanese submarine on six June, and sank a day later. Battle analysts have concluded that the critical element in the sinking of the four Japanese carriers was surprise by the U.S. dive bombers. If the Japanese carriers had radar equivalent to the American CXAM they most likely would not have been surprised, and the battle probably could have come out much differently. [5, pp.190-193] [32, p.32]

The burning Hiryu on the morning of 5 June 1942 with a large hole in her flight deck. The carrier was sent under by a Japanese torpedo about four hours later. Naval History and Heritage Command photo NH 73065 (Donation of Kazutoshi Hando, 1970)

More Criticism of Fighter Direction

Even though the Battle of Midway was considered a signal American victory, senior officers were still critical of fighter direction. Many of the problems noted in Coral Sea reports were still with them. In some instances, fighter directors were not using the correct vocabulary. For example, only Enterprise pilots knew that when the Enterprise FDO used the term “Arrow” he really meant magnetic headings rather than true, but the pilots from other carriers did not know of his practice. He was also faulted for not identifying himself in his transmissions. Identification Friend or Foe equipment was also a subject of complaint, both because many airplanes still did not have it, and also because of reliability problems. The fighter net radio channel had again been saturated to the point that FDOs sometimes could not get timely information and vectors to the fighters. The need for ‘super frequency’ radios with multiple channels so that the fighter directors could have their own inter FDO communications circuit rather than talking to each other on the fighter net was again brought up in the action reports. [11, p.21]

As at the Battle of the Coral Sea, once again a snooping Japanese patrol plane had been detected but not successfully engaged. Action reports expressed dissatisfaction with Japanese patrol planes ability to locate U.S. forces and to successfully shadow them. In a July 1942 letter, the Chief of the Bureau of Aeronautics stated:

It is particularly important that shadowing aircraft be shot down. The presence of a shadower may be the first indication of an approaching raid which will require all the concentration possible on the combat air patrol. It is unlikely that more than two fighter planes will be required to bring down the most persistent shadower, but the importance of eliminating this source of information to the enemy cannot be overemphasized. Even though the shadower may have already transmitted a contact report, it is still of value as a tactical scout, and in homing an approaching raid onto a friendly force.

With respect to the loss of Yorktown, Admiral Nimitz wrote with some approval in his action report that over half of the dive and torpedo bombers and half of their escorting fighters that attacked the ship had been shot down. He also commented on a new tactic developed by the San Diego Fighter Direction School, called the “X-Ray Formation.” The FDO was to use this order to the CAP when he was sending them out to engage a raid at unknown altitude. It would have most of the cap proceed at the given altitude, but four planes (one division) would proceed at 5,000 feet above the main body, and two (one section) would stay 5,000 feet below. It had been found since the Battle of the Coral Sea that sending planes out at 20,000 feet when raid altitude was unknown called for pilots to use oxygen which was tiring; and at that altitude low flyers could pass underneath undetected. Nimitz also wrote, “Development of tactics in stationing fighters at various altitudes and distances from the carrier, along with the Fighter Direction School now being established in Oahu, should produce further improvement.” [11, p.21]

Camp Catlin

The construction program of new aircraft carriers and the plan to place fighter directors on combatant ships other than carriers created a demand for more trained FDOs; more than the Fighter Director School at San Diego could turn out. Admiral Nimitz decided that rather than enlarge the San Diego school he would move it to Hawaii with larger facilities and staff. Furthermore, he would consolidate all Pacific Fleet training related to radar in one school. In April 1942 the Pacific Fleet staff advised Commander Jack Griffin, in charge of the San Diego school, that he was to establish a new Pacific Fleet Radar Center at Camp Catlin, located between Pearl Harbor and Honolulu. Griffin was to be Officer in Charge, and his first task would be to relocate the San Diego School to Camp Catlin. There was already a radar maintenance school at Pearl Harbor Naval Base and it would remain in place, but would come under Griffin's jurisdiction. Other components of the Center would be:

  • A radar operator’s school.
  • A radar countermeasures school.
  • A radar tactical school for senior officers.
  • A fighter director and radar plotting advanced training school, with primary facilities at Camp Catlin, and an annex at Naval Air Station, Honolulu, for hands-on fighter direction practice.

It was highly desirable that officers attending the Fighter Director and Radar Plotting School had previous sea experience. The school had six progressive courses, Course I was a one-week introduction covering basic radar theory and operations, air and surface plotting, and use of the maneuvering board. The second one-week course, Course II, had lectures on the theory of fighter direction combined with lectures and practice drills on radar plot communications. The more advanced aspects of radar operation were also included. Course III was Preliminary Fighter Direction including simulated intercept practice, more FD lectures, and advanced radar interpretation techniques. Course III was also a “weed-out” course for those slated to go on to Course V: Fighter Direction. The curriculum description noted, “Some students may not display qualifications for advancement to Course V and will be returned to their ships upon completing Course III.

Course IV was titled “Radar Plot Watch Officer Qualification Course” and also lasted one week. It included training films, lectures, and reading, as well as practical drills. Subject matter included:

  • Functions and organization of radar plot,
  • Surface tracking,
  • Surface engagements,
  • Radar interpretation,
  • Radar navigation,
  • Shore bombardment,
  •  Identification Friend or Foe,
  • Coordination of air and surface attack, and
  • Elementary fighter direction

In practice drills, the students worked as a radar plotting team in radar plot mock ups and rotated so that they were experienced in the duties of each team member. Graduates were qualified to stand radar plot watches and to run team training.

Course V was two weeks of advanced fighter direction training, and prerequisites were completion of Courses I, II, and III. Practical exercises included intensive synthetic training using the familiar tricycles, followed by live air intercept practice at Honolulu Naval Air Station Annex. Lectures included use of specific air search radars, and examples from actual fighter director battle experiences. The curriculum description stated, “Successful completion qualifies students as Interceptor, 2nd Class. Some students may not be qualified after second week; those needing only additional time to qualify are held over.” The description also noted that “...Fighter Director requires an officer of high calibre with excellent judgment and qualified by specialized training.”

Course VI was indoctrination in Radar Plot operations and tactical application of radar for prospective commanding officers and executive officers. It lasted from four to ten days depending on previous at-sea experience with radar and Radar Plot operations, and it consisted of practice drills in Radar Plot mockups, training films, lectures, and reading home work. The reading included recent action reports involving Radar Plot operations. Lectures included sample Radar Plot layouts. The ten-day course was recommended for senior officers who did not have previous radar and/or wartime experience at sea. [61, pp.246-247] [39, pp.35-38] [13, p.42]

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