Missoula County Search and Rescue Stays Connected in a Mountainous Dead Zone with goTenna Pro

Challenge

The Missoula County Search and Rescue Team (MCSAR) operates 24 hours a day, seven days a week in western Montana’s mountainous and rural terrain — rain, snow, or shine. Their team consists of three squads, responsible for highly technical mountain rescues, K9 searches, emergency medical support, and any call for mutual aid from the Missoula County Sheriff’s Office and other neighboring public safety agencies. The team relies on voice radio and mapping applications such as onX for communications and situational awareness. However, their missions frequently take them to areas where both tools have unreliable connectivity at best. A well-known “dead zone” near Gold Creek is far from the county’s established radio repeaters and particularly challenging for voice communications, as the terrain prevents critical line-of-sight for radio transmissions.

A heavily forested valley near Gold Creek in Missoula County is prone to voice radio communications failure, creating a “dead zone” for MCSAR.

When minutes can make the difference in a mountain search and rescue mission, MCSAR knew that this communications gap needed to be addressed. After some research, they decided to bring mesh networking technology from goTenna Pro into this known dead zone and put it to the test. A successful test would show how a mesh network could extend the edge of connectivity past radio repeaters and cell towers, ensuring the team could still exchange messages and mapping information without delaying rescue efforts.

Solution

Unlike a traditional communications system, goTenna Pro’s mesh networking radio devices do not rely on a central radio tower, base station, or repeater to transmit data. Each member of the rescue team, equipped with their own goTenna Pro device paired to either an iOS or Android smartphone, becomes a single “node” in a mobile, ad hoc mesh network where data hops from device to device. In order to overcome line-of-sight challenges in the forested and mountainous terrain, spare goTenna Pro devices can also be set in a standalone relay mode and placed in strategic, high-altitude locations to extend transmission range and hop potential. goTenna Pro’s mesh networking technology specifically supports low-bandwidth data transmissions, such as text messaging, mapping, and location tracking. While MCSAR wouldn’t be able to use voice radio communications in the dead zone, the goTenna Pro native app provides a redundant means of maintaining situational awareness on a single screen —and on the team’s existing mix of iOS and Android smartphones.

An MCSAR team member transported charging goTenna Pro devices to the test site using a goTenna Pro Deployment Kit. Once on scene, the team quickly synced their devices and apps with the latest mapping information.

As with any mission, shared teamwide maps are essential to effectively and efficiently covering a search area. MCSAR utilized a goTenna Pro Deployment Kit to store and quickly sync the team’s devices and apps with the latest mapping information. Each Kit also contains an internal hotspot and battery source, should any team members arrive on scene with a low-battery device or a smartphone without the goTenna Pro app downloaded. After a brief pre-deployment training on the goTenna Pro devices, app, and Kit, the team was ready to put the mesh network to the test.

Results

For a full day of testing, six goTenna Pro devices were distributed across individual rescue team members and relays in the known dead zone — about four miles into an offshoot valley of the Gold Creek drainage area. The location was easily accessible by vehicle, so the team’s radio devices were attached to their two Utility Terrain Vehicles (UTVs) as well as the backpacks of two All-terrain Vehicles (ATV) riders, and paired to a single smartphone within each vehicle. The remaining two radio devices were used as relay nodes without a paired smartphone and attached to trees about six feet off the ground in separate locations within the testing area.

The distance from the MCSAR staging site to the farthest relay was approximately 4 miles. 

During the test, an ATV rider drove into a valley until they lost communications on their voice radio. Even from their location in the known dead zone, the team could still use the goTenna Pro app to send text messages and share mapping information back and forth with the ATV rider who would have otherwise been completely disconnected. The data transmissions overcame line-of-sight challenges through the closet goTenna Pro relay node, which transmitted data to the rest of the teamwide mesh network. goTenna Pro’s off-grid location tracking features also provided enhanced situational awareness, even to the team members who were still able to communicate via voice radio. A feature in the goTenna Pro app enables automatic position location information (PLI) updates at intervals from 5 to 300 seconds. MCSAR set their devices and apps to ping updated PLI every 30 seconds, so the mission operations chief stationed at the main staging area could track their vehicles in motion without clogging voice radio traffic.

Two goTenna Pro devices were tied to UTVs with zip ties, and paired to the driver’s smartphone using a  Bluetooth LE connection. 

The goTenna Pro devices were not only able to withstand the thick forests and mountainous terrain, but also rainy and wet weather conditions. goTenna Pro devices are built to IP68 specifications, ensuring dust and water resistance during austere rescue missions. The rugged testing environment did not impact device battery life either — MCSAR’s devices remained charged for over 6 hours of use with no loss in data. The test revealed that goTenna Pro’s low-bandwidth mesh networking technology could have far-reaching applications in MCSAR’s typical mission sets. While the team successfully demonstrated how the devices could form a redundant communications network when voice radios fail, they also discovered new mapping and location tracking capabilities in the goTenna Pro app that streamlined mission planning as well as command and control. In the future, MCSAR plans to deploy goTenna Pro devices with every search team member or vehicle in order to stay connected and aware in areas where it was previously impossible.