China has successfully tested an innovative airborne electromagnetic detection system, known as the Airborne Transient Electromagnetic (Atem) system, which could potentially locate hidden nuclear submarines beneath the ocean surface. Developed by a research team led by Fu Jingcheng, PhD, from Beihang University and the Chinese Academy of Sciences, the system features three large dodecagonal coils, each measuring approximately 82 feet (25 meters) across. These coils are suspended from a helicopter and emit powerful electromagnetic signals to detect submerged objects by analyzing secondary electromagnetic signals produced by conductive materials below the surface. The research team faced challenges in maintaining the stability of the coil array during flight, as wind and helicopter maneuvers could affect data accuracy. To address this, they developed a computer model to optimize cable lengths and tensions and added a flexible aerodynamic film to stabilize the coils. A successful seven-minute test flight confirmed the system's capability to maintain the necessary orientation for precision measurements. The findings were published in the journal Acta Aeronautica et Astronautica Sinica on April 25.