Drone Use in SAR – Part Two: Preparation and Operation
-Article courtesy of Mike Scott
In case you missed it, you can read Part One: Selecting the right UAV here
There is a lot to think about when using a UAV to support a SAR mission and we will have a look at a couple here: Mission planning and Payload operation.
We will have to save search patterns for the third installment as this might be a bit much to cover all in one go.
Remember, that the mission you are flying is “User” directed. That user could be the Search Team Lead, Rescue Coordinator or even the Police. Be patient when explaining what you can and can’t do with your UAV. In many cases the User will not know much about UAV’s and or the capabilities. It will be up to you as the pilot to walk them through this.
Ensure you have been briefed by the User prior to the flight. This gives you the overall scope of what has been happening in the search so far and could impact your mission. Look at images of the area or consult any maps that may be on site. Talk with any who may have been in the search area recently as new trails may not be on the maps you have access to. This will make for the best use of flight time. Always plan to do one more launch than you think you may need. Many times, its right near the end on a flight when you spot something that needs a closer look.
We will get into the payload operation and a few search patterns in a bit, but for now let’s just talk about the conduct of the mission. First and foremost, stay on task. It is very easy to stray away from an intended search area if you continually follow that little something at the edge of the screen. Maintain you situational awareness by checking you moving map frequently if you have one.
You should be in constant contact with the User. This can be tricky when you first start out, trying to fly and talk on a radio. When possible, have a second member with you to give and take new information as it comes up. However, those of us that played telephone as a kid will know, the more times info is passed along the more diluted it gets. Many SAR teams have radio training as part of the overall basic training. Some radio networks are very relaxed and can sound like two guys chatting on the phone, while others are much more ridged and strictly use 10 codes or even code words. Whatever the system your team uses, practice it with the UAV on the ground using scenarios. Also, don’t bother making contact until you know you have a good UAV and the payload is working in flight. Calling “Skitter 1 is airborne” only to realize the IR camera won’t turn on. You may be in for a short flight. My last bit of advice for this section is this, report only what you see and not what you think. Don’t speculate or guess about what you are looking at, just describe it as best you can.
Payload operation can be broken down to a few smaller elements and will differ slightly depending on the UAV you are using. I will try to cover the most common features, but if you are even in doubt, please contact the UAV manufacturer for further details.
So let’s jump right into Buttonology. You have lots, so let’s use them all! A majority of the buttons or switches that you have will be focused around the payload, while some will be primarily for flying the UAV.
EO/IR toggle. If equipped with a dual camera set up you can change cameras while in the air you’re your control unit. Electro-Optical or DLTV (daylight TV) is good for picking out colours and contrast while searching the area. The added benefit of having an IR (infrared) camera is the ability to check the temperature of surrounding objects and compare them to what you are looking at. Remember, despite what you have seen on TV or in the movies, you will not be able to see into buildings, through glass or into water. So when is the best time to use either EO or IR? The easy answer is all the time. The EO camera can be used at night to check for the presence of flashlights, headlights or the flicker of fire against the trees. Conversely, the IR camera is still very effective at locating object in the middle of the day as it looks at the surface temp of the objects within the field of view. For example, if it just happens to be 110 in the shade, a person at 98.6 will show up as a cooler object. Below is an example of a black and white DLTV image and the IR version taken at those temps as well as a colour DLTV/IR for comparison.
In the top DLTV photo you can probably see 2-4 people, but in the next one that is in IR with black hot/ white cold you can see many more (7). And below shows white hot.
There will be two times during a 24 hour period when the IR camera will struggle to differentiate between object temperatures. This is called the Diurnal Cycle, IR Crossover or Thermal Crossover.
As you can see these times will change based on the local sunrise and sunset. A rule of thumb is: an hour after dawn and dusk lasting between 10 – 30 minutes you will encounter this effect. We will talk about how you can lessen this effect if you have ability later on, but for now just knowing this happens will make flying at those time a bit less frustrating, I hope. Below is another example. See how many people you can pick out on this photo. I will show you the IR version later on, or you can scroll down if you’re the kind that needs a sneak peek right away.
Polarity. Working in white hot or black hot will depend on you and your eyes. However, black hot is much easier on the eyes and closer to the way we see things and you won’t be bothered by the halo or bloom effect that is common when using white hot.
Zoom. There are two types of zoom you will find in these cameras: optical and digital. Whats the difference you might ask. Well, optical zoom gets up close and personal by using the camera actual lens adjustment and digital zoom adjusts the image in the camera itself normally by enlarging the pixels of the image. The example below shows the difference in the images you get:
Frame Rate. Having the ability to adjust the frames per second can help get rid of the “chunky” looking or “stuttering” feed. Going from 15 FPS (frames per second) to say 30 FPS will result in smoother footage. However, this may lead to less detail as the image is scrolling by faster. You may want to reduce the FPS to gain detail when searching through a very busy area.
This will become very apparent when using IR, but will depend on the quality of the camera as well.
Ok, I think we will call it on this installment for now. I will follow up with a dedicated post on search patterns as well as acquiring and tracking. For those of you that held on to the end, below is the IR version of the field I talked about earlier.
So it turns out there are quite a few in the photo. Did you see them in the EO/DLTV shot? Thanks for taking the time to read through this post and I hope you keep following for part 3.
*All UAV operation should be limited to manufactures recommended flight parameters and local aviation laws.