This week, Philippine fishermen recovered a Chinese surveillance drone off the coast of Ambulong Island, well within the archipelago's internal waters. The small island is about 400 nautical miles away from the nearest Chinese bases in the South China Sea, including at least 100 nautical miles of coastal pilotage through the Philippines' central islands.
The drone is about six feet long, and is marked "HY-119." The police have turned it over to the Philippine Navy for further analysis, and an investigation is under way, according to the Armed Forces of the Philippines.
"The recovery of the HY-119 system has significant implications, as it provides insights into advanced underwater technology and naval capabilities," said the Philippine National Police in a statement.
Col. Xerxes Trinidad, a spokesperson for the Armed Forces of the Philippines, thanked the local fishermen for finding the suspicious device and turning it in. Philippine Navy sources told local media that the drone sub is believed to be a Chinese ISR device, capable of monitoring, recording and transmitting data.
Images courtesy Philippine National Police
The device's "wings" and its lack of propeller identify it as a seaglider, a submersible that changes its buoyancy in order to rise up through the water column, then "glide" at an angle on the way back down. This is a slow but energy-efficient method of propulsion for unmanned underwater vehicles, and has been developed extensively by the U.S. Navy.
Because this type of drone rises and falls through the water column, it is useful for collecting certain oceanographic data - salinity, temperature, currents and other physical measurements - that are essential for hiding submarines from acoustic detection. Seagliders can also be used to covertly carry out hydrographic surveys, or to listen for the movements of enemy submarines.
The glider found Monday is similar in appearance to three suspected Chinese spy drones that were recovered in Indonesia in 2019-20. All of these drones share a resemblance to the "Sea Wing" (Haiyi) UUV developed by the Chinese Academy of Sciences.
Courtesy Chinese Academy of Sciences
Courtesy Chinese Academy of Sciences / IOCAS
"If this is a Chinese drone, as seems likely, it indicates a troubling level of Chinese interest in the Philippines' internal archipelagic waters," Chinese maritime strategy expert Ray Powell told the Philippine Star. "[This] could mean that China intends to deploy submarines into Philippine waters, or perhaps wants to have that option if conflict breaks out."
