‘Detection dog’ ‘WC-135’ in the sky…looking for evidence of nuclear tests and explosions

A U.S. Air Force nuclear detection reconnaissance aircraft ‘WC-135W’ is landing at a base in Okinawa, Japan. Photo Credit: Yonhap News

Known as the “Nuke Sniffer,” the WC-135 ‘Constant Phoenix’ is equipped with advanced equipment capable of collecting particulates in the atmosphere and analyzing them in real-time. Based on the air samples collected from each region, it can determine in real-time whether a nuclear test or explosion has occurred. It is also known to be able to identify the type of nuclear bomb used in the experiment.

The special reconnaissance aircraft WC-135, a sibling of the RC-135, is considered one of the U.S. military’s key reconnaissance assets. In 2017, when information about North Korea’s sixth nuclear test was imminent, the WC-135 Constant Phoenix made an emergency sortie to the East Sea and monitored all over North Korea. So far, it has been deployed around the Korean Peninsula before and after all six nuclear tests conducted by North Korea.

The WC-135 detects radioactive materials through an atmospheric sample collection device, shaped like an engine, attached to the side of the fuselage. When the internal temperature of the air component collector inside the reconnaissance aircraft is lowered to below -50 degrees Fahrenheit, nuclear materials in the air stick to it. It operates on the principle of collecting radioactive materials such as xenon and krypton, which are emitted when atoms are artificially broken during the nuclear explosion process. By analyzing the measured content, it is possible to determine whether a nuclear test has been conducted, whether it is enriched uranium or plutonium, and the type of bomb.

10 U.S. C-135Bs Converted to Nuclear Detection Aircraft

During World War II, the United States dropped the first atomic bomb on Hiroshima on August 6, 1945, resulting in the death of 70,000 people. Three days later, on August 9, a second nuclear bomb was dropped on Nagasaki, killing 20,000 people. After experiencing the overwhelming destructive power of nuclear weapons, Japan declared unconditional surrender.

As a new asymmetric weapon, nuclear weapons, which are considered the greatest tragedy in human history, began to be developed in earnest by countries around the world. In response, the Eisenhower administration in the United States launched the ‘Constant Phoenix’ program to detect the intention of nuclear development in each country and to detect any nuclear weapons tests in advance. This was the starting point for the emergence of special-purpose aircraft for nuclear detection.

The U.S. Air Force chose the C-135B as the basic aircraft. It was filled with measuring equipment capable of collecting atmospheric samples from the nuclear test area and analyzing them in real time. The U.S. Air Force converted a total of 10 C-135Bs into special-purpose aircraft. These aircraft were assigned to the 55th Weather Reconnaissance Squadron at McClellan Air Force Base in California as part of the U.S. Air Force’s Air Force Weather Agency.

The aircraft was clearly labeled with the nuclear detection program name ‘Constant Phoenix’ to clarify its purpose and use. The WC-135, which was mainly used to detect signs of nuclear tests in communist countries, retired most of its fleet with the collapse of the Soviet Union in 1990. Only one of the original ten was upgraded with combat equipment and sensor equipment and continued to operate as the WC-135W. However, by the end of the 1990s, it was difficult to detect signs of nuclear development around the world with just one aircraft, so one EC-135 command and control aircraft was converted to WC-135 specifications and named the WC-135C for additional deployment.

U.S. Air Force special reconnaissance aircraft WC-135 ‘Constant Phoenix’. Photo Credit: Offutt Air Force Base

The basic fuselage of the WC-135 is the C-135B, which was developed as a military aircraft based on the Boeing 367-80 and Boeing 707 civilian aircraft from Boeing. Inside, it is equipped with equipment capable of detecting particulates, gas emissions, or debris in the atmosphere. The atmospheric collection device can collect and analyze a radioactive ‘cloud’ in real-time.

On the outside of the fuselage, there is a U1B, a device that analyzes particles filtered by a paper filter as the air passes through, and a special-purpose compression device that can collect air samples from a specific area. Once the necessary air samples are collected, the compressed air and paper filter are transmitted to the U.S. Air Force Technical Applications Center (AFTAC) via a network, and analysis is then conducted in the laboratory.

The WC-135 can accommodate up to 33 passengers depending on the mission. The aircraft pilot is stationed at the 45th Reconnaissance Squadron at Offutt Air Force Base in Nebraska. The special analysis equipment operator is a member of the 1st Dispatch Battalion of the U.S. Air Force Technical Applications Center.

The U.S. Air Force conducted preliminary research until 2002 and began development, completing aircraft mounting tests to be installed on the RC-135 trainer. In 2003, the Initial Operational Capability (IOC) of AARE was declared, and through this, the WC-135 acquired the ability to detect and capture nuclear signs and collect and analyze samples for over 50 years.

A member of the WC-135 crew analyzing the measurement data. Photo Credit: U.S. Air Force

The existence of the WC-135 began to be known to us as the North Korean nuclear issue emerged. Whenever there were signs of a nuclear test in North Korea, it was deployed on the Korean Peninsula to collect air samples. The analysis confirmed the occurrence of North Korea’s nuclear tests.

As soon as North Korea showed the first signs of a nuclear test in October 2002, it was urgently dispatched to Kadena Base in Okinawa, equipped with radiation detection equipment. At that time, the WC-135 flew around the Korean Peninsula, collecting radioactive materials that would have spread from a nuclear explosion, and returned to Kadena Base on February 4, 2003.

In 2004, as signs of North Korea’s nuclear test became frequent, the newly deployed WC-135C flew a total of 23 sorties for 100 hours. The WC-135W flew 83 sorties for 609 hours, detecting signs of North Korea’s nuclear test. Through this, they were able to analyze evidence of North Korea’s first nuclear test from the atmosphere.

The WC-135 has been deployed around the Korean Peninsula to collect evidence whenever the North Korean nuclear issue arises. Successful collection and analysis of evidence of North Korea’s nuclear tests were carried out in September 2016 when the fifth nuclear test was conducted and in March 2017 when the sixth nuclear test was conducted. It is expected to be deployed again on the Korean Peninsula in anticipation of North Korea’s seventh nuclear test, which is expected in the first half of next year.

On December 4, the newly deployed nuclear detection reconnaissance aircraft ‘WC-135R’ Constant Phoenix is receiving maintenance at Offutt Air Force Base in Nebraska, U.S. Photo Credit: Offutt Air Force Base

Following the U.S. intelligence agencies’ assessment that the possibility of North Korea’s seventh nuclear test is high, the U.S. Air Force has completed upgrading its reconnaissance aircraft fleet by deploying additional nuclear detection reconnaissance aircraft.

According to Offutt Air Force Base on December 17 (local time), a new special reconnaissance aircraft for nuclear detection, the WC-135R ‘Constant Phoenix,’ was additionally deployed at this base in Omaha, Nebraska on the 4th of this month. The base stated, “This is the third and final arrival,” and “With this, the Air Force reconnaissance aircraft system has been reorganized from the existing two WC-135W aircraft to three WC-135R aircraft. It has taken over four years since we started strengthening our nuclear detection capabilities in 2019.”

The WC-135R is a special reconnaissance aircraft for nuclear detection. It supports the determination of nuclear tests or nuclear explosions by collecting and analyzing air particles and gases in areas where there are signs of nuclear activity through an atmospheric sample collection device attached to the side of the fuselage. This mission is known to be participated in by the 45th Reconnaissance Squadron and the 21st Surveillance Battalion of the U.S. Air Force Technical Applications Center.

The first and second WC-135Rs were deployed at Offutt Base in July last year and May this year, respectively. As more countries are developing or effectively possessing nuclear weapons, the improvement of the nuclear detection reconnaissance aircraft to the latest model of three aircraft means that the U.S. Air Force can collect atmospheric samples related to nuclear activities in more regions around the world, according to the base’s explanation.

James Finlayson, the Director of the U.S. Air Force Technology Applications Center, stated, “For the first time in U.S. history, we now can respond to nuclear incidents or explosions occurring simultaneously worldwide without degrading mission performance or transitioning assets.

WC-135R Fleet Collects Evidence of North Korea’s 7th Nuclear Test

The WC-135 series reconnaissance aircraft have been active over the East Sea since North Korea’s first nuclear test in 2006, responding to actual nuclear tests or capturing nuclear test-related developments.

In September, a U.S. WC-135R took off from Kadena Air Base in Okinawa, Japan, and entered the East China Sea Air Defense Identification Zone (ADIZ), prompting suspicions that it was trying to observe Chinese military exercises.

One of the primary missions of the reorganized WC-135R fleet is to monitor signs and collect evidence related to North Korea’s 7th nuclear test. The WC-135R reconnaissance plane is a modification of the KC-135R, previously used for aerial refueling. In a report to the National Assembly’s Intelligence Committee in November, the National Intelligence Service stated that “nuclear tests are a matter decided by North Korea’s top leader” and that “depending on the determination of Chairman Kim Jong-un, there is a possibility that North Korea could conduct a nuclear test at any time in 2024.”

By. Hyun Ho Lee