Determining that rescue work required quick response, after receiving the news, Viettel Network Corporation mobilized all the engineers and experts in the core network and radio fields of the Technical Center of Region 2 to participate in the mission.
Immediately, the team analyzed the subscription history, predicted the route, and identified the transmitter stations near the landing area of the two pilots. However, the landing location of both pilots was deep in the primeval forest, with hidden terrain and many valleys, making the location difficult to determine. At this time, the plan to adjust the antenna and increase the power of the transmitter stations was considered.
Signals "penetrate" complex terrain to save people
On one hand, the technical team used remote control technology to make changes; on the other hand, a team of district staff from Viettel Binh Dinh was sent to directly adjust the hardware on the antenna at the designated stations. After adjusting, the team continued to push, increase the maximum transmission capacity of the stations, using low frequency bands to enhance coverage.
Accordingly, the antenna's transmission power is increased 4 times, the angle of the transmitting antenna is adjusted to expand the station's coverage area by 5-7 times, from a radius of 1.5-2 km to 7-8 km, while 4G coverage covers the surrounding high mountains. Normally, signal boosting is only used in emergency situations such as rescue and relief. Because if the power is increased too much, the coverage area between the stations will overlap, leading to the customer's usage speed being affected, and the user experience being worse.
Through analysis, the Viettel team determined that the two pilots landed in two different directions, so they had to continuously adjust to find the broadcasting station with the signal. After about 15-20 minutes from the time the team adjusted, the first good news was returned, Lieutenant Colonel Nguyen Hong Quan - one of the two pilots - was able to contact the unit by mobile phone, at about 4:30 p.m. the same day.
Meanwhile, finding Colonel Nguyen Van Son's location was more difficult because the pilot's landing site was hidden deep inside and the signal was difficult to reach due to the obstruction of many trees and rocks. After many attempts to navigate the coverage area and continuously call Colonel Son's phone, the technical team finally received a response signal at 6:45 p.m.
From these calls, Viettel's technical team continued to instruct the two pilots to use 4G data waves to send coordinates back to the unit. At the scene, the rescue team quickly came up with a plan to organize a rescue approach.
Timely rescue thanks to terrain knowledge
Mr. Nguyen Quang An - an employee of Viettel Binh Dinh branch - directly joined the search team as soon as he received the order. Mr. An used to be a technical staff at Tay Son - Vinh Thanh cluster, specializing in installing broadcasting stations in mountainous areas, so he was familiar with the terrain.
Viettel Group Chairman - Major General Tao Duc Thang - personally called Mr. An, assigning him the task of following the determined coordinates to rescue the victim as soon as possible. Receiving the call, Mr. An was both surprised and honored. Fully understanding the assigned responsibility, the male employee was determined and ready to set off, going deep into the mountainous area.
As a navigator, every 20-30m, An checked the coordinates once to make sure the group was going in the right direction. Because in the dark, the forest path was already dense and difficult to travel, and even more difficult when the weather was rainy, windy, and the rocks were slippery. Above, two locals were leading the way, holding flashlights to find the way.
At around 8:00 p.m. the same day, Lieutenant Colonel Quan was found on a mountain in the Ham Ho area, Tay Phu commune, Tay Son district, about 10 km from the parachute drop zone.
Sharing more about the rescue process, Mr. An said that after finding Colonel Quan, the whole team was exhausted, and most of the phones they brought were out of battery. The team considered letting another team come in to rescue Mr. Son. But when checking the coordinates, they discovered that Mr. Son was not far away, about 600m, so the whole team was determined to rescue the remaining pilot. One group was divided to take Mr. Quan out of the forest, while the other group continued to search.
Although on the map, Mr. Son’s hiding place was very close, in reality, it took the rescue team another 2 hours to reach the correct location. The mountain road was slippery due to heavy rain, the whole team had to grope around in the dark, many times slipping and falling or crawling, clinging to the ground. The raincoats they brought were almost torn by the trees, some had to take them off and continue walking in the rain.
"We told ourselves we didn't want to make Mr. Son wait any longer, and we didn't know if he was injured anywhere, so we encouraged each other to keep going," Mr. An recounted.
All efforts were rewarded when at around 10:20 p.m., the rescue team found Colonel Son. As they neared the location, everyone started calling out Son's name. The moment they heard the pilot's voice respond, the whole team burst into tears and rushed to the source of the sound.
After nearly 8 hours of rain and deep into the rugged rocky mountains, the rescue team completed their mission. “My daily work gave me some experience in the terrain of the area and the operation of the stations deep in the mountains. But this ‘mountain crossing’ was truly memorable because the whole team had to wade through the forest in heavy rain, with no trails to follow. When I rescued both of them, I was really happy, forgetting all the hardships,” An said.
Leaving the forest at midnight, An immediately returned to his leader to report that the mission was completed and the whole team was safe. At 3am on November 7, An returned home.
Major General Vu Hong Son - Deputy Commander, Chief of Staff of the Air Defense - Air Force - sent his sincere thanks to Viettel and other units for their coordination and efforts to bring the two pilots back safely as soon as possible.
Lieutenant General Pham Truong Son - Deputy Chief of the General Staff of the Vietnam People's Army - highly appreciated the rescue work this time. "Using many technical measures, the units calculated every detail, found the location of the two pilots to deploy search forces in the most reasonable way. Heavy rain, strong winds, very fast flowing rivers, deep forests, high mountain slopes, but the forces quickly brought the two pilots back in very complicated weather conditions", Lieutenant General Pham Truong Son commented.
