Taiwan's Teng Yun military drone appears to draw a Double Ten over the mountains on National Day

Taiwan's Teng Yun medium-altitude long-endurance drone, developed by the military-run National Chung-Shan Institute of Science and Technology (NCSIST), appears to have flown a route over the Central Mountain Range on Saturday morning that traced a giant Double Ten, the symbol of the Republic of China's National Day, according to flight-tracking data shared by aviation enthusiasts and reported by the Liberty Times, the United Daily News and CTi News.

The aircraft, shown on the Flightradar24 tracking site under the code TU501, took off early on 10 October from the air force base in Hualien on Taiwan's east coast and headed west over the mountains, the reports said. Above the Central Mountain Range and the Puli area of Nantou county it made a series of turns of close to 90 degrees that, on the tracking map, formed two Chinese characters for ten side by side.

The United Daily News said the drone carried the military registration 90-15801 and that the pattern was flown during a test flight, with the drone's navigation and automatic flight-control systems holding it on a precise and symmetrical route.

An informed source told the Liberty Times that the sortie was mainly supporting the air force with airborne communications relay and intelligence, surveillance and reconnaissance during the National Day period. CTi News carried the same account, citing the Liberty Times and the United Daily News.

Television station TTV described the flight as a routine test sortie and said the military and NCSIST usually keep the details of such flights quiet. Mirror Daily noted that the public information came mainly from track records and social media posts, and that neither the military nor the institute had confirmed whether the route was designed for National Day or whether the drone was flying relay or reconnaissance missions.

Su Tzu-yun, director of the defence strategy and resources division at the government-funded Institute for National Defense and Security Research, told TTV that the angles of the turns and the symmetry of the pattern showed that the drone's flight control and positioning were very precise. He added that locally made flight-control processor chips had begun to be supplied this year, and that mass production of locally made image chips for infrared sensors could start at the end of the year, filling out the domestic supply chain.

According to NCSIST material cited by TTV, the Teng Yun is a large, locally built long-endurance drone whose peacetime missions include aerial imagery surveillance and reconnaissance, electronic signals collection, electronic jamming and weather observation. Mirror Daily said the series is designed for long loiter times and can be used for reconnaissance and other military purposes.

The Liberty Times said the flight took place as Chinese military aircraft and ships continued to operate around Taiwan during the holiday, and that national security officials said a Japan Maritime Self-Defense Force P-1 maritime patrol aircraft was also monitoring the waters and airspace around Taiwan at the same time.

Screenshots of the track spread quickly through military fan groups after the Taiwan ADIZ page and other enthusiasts posted them, with many users praising the drone's precision and wishing the Republic of China a happy birthday, the reports said.