Small Unmanned Aerial Systems (UAS) are an emerging technology that may offer significant benefits to search and rescue (SAR).
In essence, they are remote aerial cameras, controlled by an operator safely on the ground. While they can be programmed to fly a pre-programmed flight pattern, there is always an operator in the loop.
UAS offer some of the same advantages as helicopters. They can potentially search larger areas of ground more quickly, find missing subjects sooner, and potentially save lives. They can also search areas that are extremely difficult or dangerous to search by foot, reducing the risk to searchers.
UAS also offer other benefits. They can fly in situations that would be too dangerous for helicopters: bad weather, or confined areas where clearance to the helicopter rotors would be problematic.
To search a steep canyon or ravine, we may need to deploy climbers on ropes, but there is a limit to how far they can then search laterally. These situations are ideal to deploy UAS, because we could search a steep, rugged area that a helicopter may not be able to access, and more quickly and safely than using teams on lines.
If we can find missing subjects sooner, it allows us to focus our finite resources on reaching them and rescuing them. Searching is far more resource intensive than a rescue.
King County Search and Rescue provides trained volunteers that also assist with evidence searches, many of which are crime scenes. We are also frequently called out to recover deceased subjects. When the medical examiner staff cannot safely reach the deceased subject, we are asked by law enforcement to take pictures of the subject and scene. Aerial pictures from UAS could be very helpful pieces of documentation in establishing cause of death, or capturing a crime scene.
Challenges
The greatest operational challenge with UAS today is endurance. Most “multi-copters” can stay aloft for 15-20 minutes using Lithium-ion Polymer (Li-Po) batteries. While this amazing feat wasn’t possible ten years ago, it means that it is important to deploy UAS as close as possible to the search area, given the limited flight times. It also means that we may need to launch multiple times to search a relatively small area.
Plane-type UAS – either electric or gas powered – offer longer flight endurance, but aren’t able to search rugged or confined terrain. While some are hand launched, successful recovery requires extensive training.
Getting usable real-time imagery from UAS is also difficult. While standard definition video can be transmitted live, the range may be limited by terrain. High definition video and still cameras can take images that can be examined later, but this is potentially a time-consuming process. Manned aircraft like helicopters have the benefit that one of the pilots or observers can examine the images in real time and report back or redirect the course of the aircraft.
Helicopters typically fly at 400-1200ft above ground level (AGL) using the thermal camera. UAS have some similar limitations to helicopters and other manned aircraft. Trees and thick vegetation can greatly reduce the effectiveness of thermal or visible light cameras.
It may be possible to fly UAS “multi-copters” below the tree canopy, though this increases the chance of crashes. With the cost of low-end UAS reducing, it may be acceptable to deploy several cheaper multi-copters, even if one or two are lost during the course of the mission.
Conclusion
Many people have expressed privacy concerns over so-called “drones.”
King County Sheriff John Urquhart is cautiously optimistic in his view about their potential use:
“Unmanned aerial systems can be a very good tool for law enforcement, including search and rescue. But the public isn’t quite ready for them yet…. especially in an urban environment. And if the public isn’t ready then we aren’t going to use them. I’ve supported reasonable restrictions on their use, including a search warrant in some situations, as long as we could still use them in exigent circumstances.”
We’re also hopeful for the prospects of unmanned aerial systems for search and rescue. By using these remote aerial cameras we can reduce the risk to our ground teams and helicopter pilots, find subjects more quickly and save lives.
Editors Note: Read about out how the Draganfly XS-4 ES UAS was instrumental in a life-saving mission in Saskatchewan last month.
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