THE U.S. ARMY'S AIR WARNING SYSTEM (AWS)
The key to the Hawaiian Islands air defence was the air warning system (AWS), consisting of radar units, an air warning center at Fort Shafter, Oahu, located 4.9 miles (7.9 kilometres) east southeast of Ford Island in Pearl Harbor, and the 14th Pursuit Wing at Wheeler Field, Oahu, located 9.4 miles (15.1 kilometres) located north northwest of Ford Island in Pearl Harbor. As the heart of the AWS, the air warning center contained an information center, fighter director, and an aircraft/antiaircraft weapon control system. The information center needed to receive data about incoming aircraft, either from long-range reconnaissance, units stationed on the outer islands, surface ship contact, or radar in order to operate. Aircraft plotters marked the flight paths on a table map where the director, with liaison officers from the U.S. Army Air Force's 14th Pursuit Wing and 18th Bombardment Wing at Hickam Field, Oahu, located 2.0 miles (3.2 kilometres) south of Ford Island in Pearl Harbor, the U.S. Navy, and civilian aviation, identified them as either friendly or unknown. If marked unknown, the director ordered fighter interceptors launched, under the aircraft controller's direction, to investigate. This was how the British operated their aircraft warning system, and in theory this was what the U.S. Army's Hawaiian Department had in place at Fort Shafter. In actuality the system used in Hawaii bore little resemblance to the British system. The whole AWS idea was so new to the Army that no one was sure how to make it work or who should control it. The cooperation needed among various military units and government agencies was far greater than anything anybody realized at the time. Because the mobile radar systems were the first units developed for the AWS, the Army Signal Corps took initial control. The Signal Corps had planned to deploy nine radar stations, three fixed and six mobile. By 7 December 1941, the six mobile stations were in operation but the towers for the three fixed stations were on the dock at Oakland, California. After the Signal Corps had set up the system and trained the personnel, control would pass to the Hawaiian Air Force. Contrary to popular belief, the air warning system as used in Hawaii on 7 December 1941 was under the Army Signal Corps, not the Hawaiian Air Force.
Lieutenant Colonel Carroll A. Powell, Army Signal Corps, was in charge of the Hawaiian air warning system that morning. To help Powell in setting up the system and to take operational control upon its completion, Brigadier General Howard C. Davidson, Commanding General 14th Pursuit Wing, selected the 44th Pursuit Squadron (Interceptor) Commander, Captain Kenneth P . Bergquist. Although Bergquist was known as a troubleshooter and had a reputation for getting the job done, the task of making the air warning system work before 7 December would prove to be too much for even his abilities. Everyone wanted to get into the act. Even the simplest job took months of coordination and frustration before it could be completed. Oahu abounded with US Government-owned locations suitable for the mobile radar units; but before a site could be used, approval had to be obtained from the National Park Service and the Department of Interior. More than once, Lieutenant General Walter C. Short, Commanding General Hawaiian Department, U.S. Army, had to intervene to get the approval process moving. Cooperation within the Army was no better. Captain Bergquist placed a requisition for headsets to be used by personnel operating the control center, only to have it disapproved by the Quartermaster Corps because the latter thought the Signal Corps was the organization in charge and, therefore, authorized to request items.
After completing the air warning center construction at Fort Shafter, personnel needed to be trained to operate it. The Army's Signal Corps handled training for the personnel required to operate the radar units and those at the air warning center involved in tracking the reports on incoming aircraft. Captain Bergquist, with Captain Wilfred H. Tetley, U.S. Army Signal Corps, and Lieutenant Commander William Taylor, USN, managed training of directors, controllers, and those personnel who would be temporarily assigned to the system during exercises and wartime operations. Tetley and Taylor were detached from their respective units and in no way represented the Signal Corps or the Navy during this training phase. In other words, the Signal Corps trained part of the personnel and the Hawaiian Air Force the rest, with no one in command of the complete training. During the two main exercises held with the U.S. Navy in 1941 and during several smaller exercises conducted by the center itself, either the director knew the direction of the attacking aircraft or personnel from the other branches would report for the exercise as liaisons so the incoming aircraft could be identified. On 12 November 1941, after the center was manned, the Navy launched a simulated strike from an aircraft carrier 80 miles (128.7 kilometres) out to sea. The radar stations easily picked up the attackers, the center quickly identified them as enemy aircraft, and within six minutes interceptor aircraft were airborne and met the attacking force 30 miles (48.3 kilometres) from the island.
These exercises demonstrated that the Hawaiian air warning system would work if it had operational radar units, a fully staffed information center, and armed and ready-to-fly interceptor aircraft. During the simulated enemy attack on 12 November 1941, the AWS received information from (1) mobile radar units, (2) long-range reconnaissance aircraft, (3) ships at sea, and
(4) outer island units. The information was fed to the AWS and the director fed information to (1) U.S. Army Air Forces, U.S. Navy and Civilian aviation representatives; (2) an aircraft controller who was in contact with the 14th Pursuit Wing which controlled U.S. Marine Corps and U.S. Navy fighter units; and (3) to an antiaircraft artillery controller who relayed the information to antiaircraft artillery units.
The best General Davidson could do was to ensure at least one pilot from the 14th Pursuit Wing was on duty every day in the air warning center to learn firsthand how the whole system operated and to offer assistance to the controller in handling pursuit aircraft. To save money, manpower, and wear and tear, the six mobile radar stations only operated during the following hours:
Sunday: 0400-0700 hours
Monday thru Friday: 0700-1100 and 1200-1600 hours
Saturday: 0700-1100 hours
On the morning of 7 December, the system was further degraded when, although five of the six radar systems were operational and the enlisted plotters were on hand from 0400 to 0700 under Signal Corps direction, no director, aircraft controller or antiaircraft controller were on duty. The only officer present was First Lieutenant Kermit A. Tyler, a 78th Pursuit Squadron (Interceptor) pilot based at Wheeler Field. Lieutenant Tyler was there to observe how the system worked and assist the aircraft controller with the pursuit aircraft after they had launched. In no way was he responsible for, or for that matter expected to know how to activate, the air warning system. The most he could have done was call Bergquist (now a
major) and let him know what was going on. It is unlikely that such a call would have helped the Hawaiian air defence that fateful morning, because the third and final part of the air warning system, aircraft ready to launch, was not set up at all.
The whole purpose of the air warning system was to launch interceptor aircraft against would- be aggressors; yet, no aircraft were ready to launch and attack the enemy that morning. If the Hawaiian Air Force was expected to defend the islands, why were no aircraft on alert? Within the answer to this question is the basic reason the Japanese attack on Oahu was so successful. Few, if anyone, in the Hawaiian Department felt the Japanese would attack Hawaii despite many indications that an attack on Hawaii was possible. Rather, most people considered the Hawaiian Islands a staging area from which the U.S. Navy would sortie against predetermined targets. It was also commonly believed the Imperial Japanese fleet would attack Singapore or Malaysia, or possibly even the Philippines.
Although some Hawaiian Air Force units held exercise and full alerts on Oahu, and others deployed under field conditions, there was an air of make-believe to the deployments. When they were over, people would carefully clean and put away the equipment and ammunition for the next exercise. During the week preceding 7 December, the entire Hawaiian Department, by order of General Short, engaged in a full scale exercise for seven consecutive days. Army units from Schofield Barracks deployed, antiaircraft units drew ammunition and set up stations all over the island, and the Hawaiian Air Force armed aircraft and dispersed them to protective revetments. The air warning center was fully operational and launched aircraft against simulated attacking targets.
General Short considered this exercise a great success. After its cancellation on 6 December, personnel returned to the barracks, carefully cleaned and repaired the guns and equipment, removed the ammunition and repacked it in storage containers, and returned the aircraft to their main bases to be reparked close together because Alert One was still in effect. After doing this, each command gave the troops the rest of the day off and told them to report to work Monday. When and if war began, General Short and the other senior commanders in Hawaii felt they would be given plenty of warning to begin long-range reconnaissance, set up communications between the Army and Navy, staff the aircraft warning center, and arm and disperse available aircraft ready for deployment against the enemy. The fleet would sortie, and the Japanese would find a sky full of American aircraft, piloted by well-trained personnel eager to defend the island.
RADAR INTERCEPTS
The radar systems in use on 7 December were SCR-270B mobile radar units housed in two trailers. The unit's heart was the oscilloscope that gave a picture similar to a heart monitor in hospitals today. The operator would move the 20 by 40 foot (6.1 by 12.2 meter) antenna through a given arc until the line across the bottom showed a small spike or "pip." By adjusting the antenna and the controls on the set, the pip was enhanced until the operator could tell the approximate distance to the target. Next, the operator would look out the window to a plate mounted on the antenna base, with an arrow on it that would give the direction of the contact. Unlike today's radar scopes the antenna did not oscillate and there was no constant repainting of the picture on the scope. This system could not tell an incoming target's altitude, its size or number, nor could it differentiate friend from foe. There was also too much "ground clutter" for a distance of 15 miles (24.1 kilometres) from the transmitter to identify targets.
In July 1941 these radar sets began arriving on Oahu. Signal Company personnel began assembling them at Schofield Barracks and then began learning how to operate them. Once assembled, personnel moved them to prepared sites throughout the island. The Signal Corps planned to put up six sets. On the morning of the attack, five were operational, with the sixth still at Schofield. The five operational sets on Oahu were at Kaaawa on the northeast coast, Opana near Kahuku Point on the north coast, Kawailoa on the northwest coast near Haleiwa, Fort Shafter, and Koko Head on the southeast coast 7.2 miles (11.6 kilometres) east of Diamond Head. The best of the mobile radar stations was the Opana Mobile Radar Station which was located 230 feet (70.1 meters). The site consisted of a few tents and two equipment trailers. The radar set itself had a range of approximately 130 miles (209.2 kilometres).
The sets began operating at 0400 hours on 7 December except at Opana, which came on the air at around 0415 hours due to a delay for maintenance on the generator first thing in the morning. The operators had been on duty since 1200 hours on Saturday. They divided their tour between standing guard, maintenance, and operating the sets. The schedule called for each site to have a crew of three: one operator, one plotter, and one person to maintain the power generators. Because several units worked off commercial power and used the generators as standby power, some crews cut back to two people per shift on the weekend. Opana had two crew members that Sunday morning.
During the first two hours, no radar contacts were made. At 0613 hours, Koko Head and Fort Shafter began picking up sightings south of the island. Then at 0645, Kaaawa, Opana, and Kawailoa picked up a target approximately 135 miles (217.3 kilometres) north of Oahu heading south. All three stations called the Information Center with the targets, which were then plotted on the master plot board. Personnel at the center included five plotters (one for each radar site), a historical information plotter; Private First Class Joseph P. McDonald, the switchboard operator; and Lieutenant Kermit Tyler, a pursuit pilot. The radar sites phoned the plots to the five plotters, and no one present found anything unusual with the information. McDonald had worked the switchboard for several months and knew the radar operators, while Tyler had been to the Information Center only once before. On 3 December he had worked from 1200 to1600 hours with just the switchboard operator. On that occasion nothing had happened, because the sites were not operating. Therefore this was the first time he had actually seen personnel plot targets. When the reports began coming in, Tyler went to the historical plotter's position and talked with him about how he recorded the information. These first plots were probably two Aichi E13A1 Navy Type 0 Reconnaissance Seaplane Model 11s (given the Allied Code Name "Jake" in 1942) that had been launched from the heavy cruisers HIJMS Chikuma and HIJMS Tone at 0530 hours. The aircraft from HIJMS Chikuma was tasked with flying over Pearl Harbor to determine if the U.S. fleet was at anchor in addition to reporting weather conditions. The aircraft from HIJMS Tone was tasked with flying over the U.S. Navy anchorage at Lahaina on the northwest coast of Maui, 80 miles (128.7 kilometres) southeast of Oahu, to determine if any ships were anchored there.
At 0700 all the radar sites began shutting down. At the Information Center the five plotters and the historical information plotter shut down and left the area, leaving McDonald and Tyler behind. At Opana, Privates George E. Elliott and Joseph L. Lockard had been scheduled to work until 1200 hours, but the next shift had come back early from a pass to town so they could relieve them at 0800 hours. This meant that when the truck arrived to take them to breakfast, they would be through for the day. However, the same call that informed them about getting off early also let them know the truck would be late picking them up. Lockard was a trained radar operator and had been with the SCR-270Bs since they arrived on the island, while Elliot had just transferred into the Signal Corps from the Hawaiian Air Force and only knew how to operate the plotting board. Because the breakfast truck would be late and they were going to be off for the rest of the day, the two decided to use the time to work on Elliot's training. At 0702 hours, Elliot picked up more than 50 aircraft bearing 005 degrees at 132 miles (212 km); thinking he had done something wrong, he immediately began to check the settings. Lockard then took over the operation and also rechecked the controls. This was the biggest sighting he had ever seen since learning how to operate the system. Elliot then tried to call the Information Center, using the phones connected directly to the plotters. No one was there to take the call. He then called on the administration line and got McDonald. The switchboard operator knew both of the radar operators and tried to explain to them that he and Lieutenant Tyler were the only people on duty in the Center; all others had gone off duty at 0700 hours. (Strangely, the tour of duty for the Pursuit Officer lasted until 0800
hours.) McDonald then spotted Lieutenant Tyler and called him over to talk to Elliot; meanwhile, Lockard got on the phone and tried to explain that this was a large target and might be significant. McDonald interjected at this point that if the targets were so large, maybe they should call back the plotters so they could practice handling a big aircraft movement. Tyler thought about this for a moment and then told Lockard and McDonald not to worry and closed the conversation. The conversation lasted seven or eight minutes and Tyler told Elliott that his target was a flight of Boeing B-17 Flying Fortresses inbound from the U.S.; this occurred at approximately 0720 hours when the target was at 74 miles (119.1 kilometres), bearing 003 degrees.
Because the breakfast truck still had not arrived, Lockard and Elliott continued to track the target until 0739 hours when ground clutter interfered and the target was lost. At that time, approximately 0745 hours, the target was at 20 miles (32.2 kilometres) bearing 041 degrees. Just then the breakfast truck pulled up, so the two young radar operators shut their unit off and headed down the mountain to breakfast, not yet realizing that they had discovered the first wave of the Japanese attack.
Why had Lt Tyler told the operators not to worry, and why had he not followed McDonald's advice to call back the plotters? Tyler saw no reason to change the normal operations that morning. First, there was no alert or warning of an impending attack. Second, the U.S. Fleet's carriers were at sea and the sightings could well have been the carrier's aircraft returning to port. (The Navy would launch their carrier aircraft prior to arriving in port and have them land at one of the airfields so they could be used while the carriers were tied up in port.) Third, a bomber pilot friend had explained just a few days before that one could always tell when aircraft were arriving from the US because the local radio stations would play Hawaiian music all night. The incoming aircraft would use the music to tune their directional finders and thus locate the islands. (This was exactly what the Japanese did.) On the way to the Center, Tyler had heard the Hawaiian music, so he assumed a flight was coming in. (When plotted at the Opana Radar Site, the B-17s would bear 010 degrees, 5 degrees east of the bearing of the Japanese aircraft.) Finally, although Lockard had said this was the biggest flight he had ever seen, he did not say how many aircraft he thought it might contain. Later, Lockard would claim he knew the flight had to number over 50 aircraft to make that large of a pip on the screen, but at the time he did not give that information to anyone. Had Tyler known that the sighting was over 50 aircraft, he might have reacted differently; but with the information on hand, second lieutenants do not wake up commanding officers at 0700 hours on Sunday mornings with wild speculations.
Lockard and Elliot heard about the attack when they returned to their camp. After a quick breakfast, they returned to Opana and helped keep the site operating 24 hours a day for the next several months. The first Lieutenant Tyler heard about the attack was a telephone call from someone at Wheeler Field shortly after 0800 hours. The plotters were immediately called back, and soon a full complement began to arrive. Tyler would stay in the Center except for short rest breaks for the next 36 hours. During the morning's activities, two plots began to form 30 to 50 miles (48.3 to 80.5
kilometres) southwest of Oahu. The plots may have been American aircraft looking for the Japanese or even an atmospheric phenomenon; no one was ever quite sure where they came from. Not knowing what these were and thinking they could be the retiring Japanese circling before landing on their carriers, the senior controller passed this information on to bomber command as the possible location for the Japanese attack force. No one remembered to check the early reports coming in before 0700 hours or the Opana sighting after 0700 hours. The Opana Radar Station continued operating during the morning and tracked the Japanese aircraft when they headed north back to their carriers. The Information Center at Fort Shafter recorded these reports at 1027 and 1029 hours. However, the high command had convinced themselves that the Japanese carriers lay in a southerly direction and the radar reports were ignored. It wasn't until several days later that people assembled this information and realized the radar stations had located the direction from which the attack had come and the location of the Japanese fleet.