SAR first responders and the role of UAVs with laser rangefinders

Law enforcement and public safety agencies use unmanned aerial vehicles (UAVs) for many roles, but search and rescue (SAR), remains one of the original applications. During the early 2000s, first responders saw the potential of UAVs for SAR, despite GPS technology, battery power and sensor fusion being quite rudimentary.

The idea was to use UAVs with excellent flight endurance and sensor abilities to sweep a search area, but in the early 2000s, the only UAVs with those capabilities were large military-grade UAVs. These UAVs were too big and expensive, making them technically challenging to deploy and requiring expert pilots to fly.

From the earliest thought experiments around the potential of UAVs for SAR, first responder teams knew what they needed: an aerial area overview with sensors providing usable data, to shape situational awareness and guide effective decision-making in complex and rapidly changing environments.

The development of UAVs for SAR

A significant year in the history of SAR and UAVs was 2005, with the establishment of the International Association for Search and Rescue Robotics (IASAR). With a vision for the potential of UAVs configured for the SAR mission, IASAR’s advocacy helped guide technical innovation.

Only five years after IASAR’s founding, UAVs were deployed in the SAR role after the 2010 Haitian earthquake, rendering aerial imagery assistance to disaster response and recovery teams. A few years after the Haitian SAR missions, Texas A&M’s Robotics program used UAVs in the first responder role after a devastating tornado in Moore, Oklahoma, in 2013.

The development of better UAV applications continued throughout the 2010s, proving that compact UAVs, much smaller than military-type UAVs, could operate to every need, even linking into large and complex rescue and disaster management operations. This was evident in 2017, when compact UAVs were used extensively after Hurricane Harvey, one of the most powerful storms to make landfall in US history.

During Hurricane Harvey SAR missions, compact UAVs proved they could search comprehensively and speedily across a vast damage area, locating missing persons and direct overall rescue efforts.

With UAV technology advancing and meeting more SAR needs, training first responders to deploy the technologies best became paramount. In 2019, DRONERESPONDERS was formed, as an NGO to educate, upskill and advance the knowledge of SAR specialists in using UAVs.

Why laser rangefinders are so important for SAR

Missing persons are often in places and spaces that are hazardous to reach. Missing hikers huddled in a cave during a storm, or people stranded in trees during a flood, are examples of SAR missions where high-altitude search aircraft easily miss location during overflight.

Compact UAVs have become a preferred choice for SAR teams because they can fly and navigate challenging terrain, finding people that high-altitude UAVs and search aircraft can’t. The UAV’s mission is to enhance situational awareness. When compact and agile enough, the UAV can fly through deep ravines, under overhanging ledges, into caves, and near terrain inaccessible to large UAVs.

As part of the UAV’s sensor payload, laser rangefinders make sense of a search area by providing accurate depth perception and distance measurements. That data, in combination with the UAV’s GPS, can be developed into sharable real-time location coordinates. When a missing person or object of interest in the search area is identified, localization coordinates can be shared, helping to develop the SAR mission from its ‘search’ to ‘rescue’ phase.

Depth, distance, and location are the three elements that allow SAR teams to understand coordinates and actions within their search areas, with laser rangefinders being the sensors that bring real-time depth and distance data, to help confirm localization. With a laser rangefinder as part of its sensor payload, a UAV operating in the SAR role can facilitate quicker, more confident and accurate rescue coordination.

When a UAV assists in a mountain mission, or a post-earthquake urban setting, the search altitudes are often low. Teams want to get deep into ravines, under forest canopies, and below collapsed roof structures, that means they’re mostly operating in the mid-range, using their SAR UAV’s laser rangefinders at less than 1000m.

Thinking big with mid-range laser rangefinders

The benefits of UAVs for SAR have been so overwhelming that authorities are responding with legislation to help teams use UAVs even more effectively, especially within or around challenging airspace.

In 2021, the FAA granted its first Beyond Visual Line of Sight (BVLOS) waivers for UAVs to operate over larger areas and in more complex environments. Since then, more than 500 SAR teams across the United States have integrated UAVs into their mission capabilities.

Even in the world’s most restricted air space environments, authorities are adapting to allow more UAV use for enhanced SAR. Washington D.C. has some of the world’s most restricted air space. In June, its Metropolitan Police Department announced an expanded compact UAV program to enhance SAR abilities by adding five new UAVs.

Since the earliest first responder developments with UAVs in the 2000s, the ability to fly low and go where helicopters and large uncrewed aerial vehicles can’t, hasn’t changed. Flying high-altitude UAVs with expensive long-range sensors is excessive for many SAR missions and risks missing crucial parts of the search area, like a hiker under a rocky overhang.

SAR teams want to operate low and search along the contours or terrain, below tree canopies, beneath ledges, or through industrial and urban structures. In these scenarios, UAVs need to be compact, which means they need laser rangefinders that deliver all the ability without increasing size. That’s where an ultralight mid-range laser rangefinder, with ranges from 250- to 1000m, is a valuable part of any SAR UAV’s sensor payload.

The SAR mission hasn’t changed from those first ideas around UAVs in the early 2000s. Whether SAR missions are in mountainous terrain with deep ravines or areas where a brushfire can rapidly change direction, UAVs save lives and reduce the risk to rescuers and first responders.