Men rescued from Pacific island after writing SOS in sand

I don't think this works as well as you might hope. When in dense foliage, it's difficult to hear sounds that are not that far away. It's a fantastic noise insulator. For this reason, survival classes usually teach signalling with reflective surfaces, like mirrors, watch faces, metal object/knives, etc. If you can sweep a helicopter with a reflection several times, they'll notice and rightfully think it's man-made. Plus, you can't hear someone screaming over a helicopter anyway.

> I think the search and rescue efforts as they stand are pretty disruptive (helicopters, teams covering grids) so I don't thin this is incrementally worse.

Certainly they are, but I do think drones close to the ground would be incredibly more disruptive, and potentially dangerous to curious wildlife.

> The "unprepared skiiers" you mention are someone's child (and often someone's parent).

You are not wrong. I think I was getting at, that most rescues are unglamorous, and usually caused by sheer stupidity of the people that were lost. Boats running out of fuel because they didn't prepare properly, or the skier example of ignoring all warnings, etc. It's not often that people were prepared, and the rock beneath their feet gave-way and now they're trapped.

Yes, we have to rescue stupid people too, but I think we should weigh the external costs to the environment when doing so. We wouldn't drain a lake to find a missing person. Maybe that's not a fair comparison? I don't know... but I do know people went outdoors to experience nature, so we shouldn't destroy it trying to save people either.

I guess, in short, you can make this scheme work, but I don't think it'll add tangible benefits to rescues, and it might actually be more effort to manage and operate, which could suck resources away from actual "boots on the ground/in the sky".

There is a lot of interest already in using both off-the-shelf and more purpose-built drone technologies in search and rescue. They currently have too many limitations: they cannot navigate complex tree canopies close enough to the ground to provide reliable visual contact with subjects; their flight time is so limited that deployment and management is a real pain for large search areas; and if they aren't fully automated then you get the same signal problems with your remote that we have with our much more powerful radios with the added benefit of extremely powerful repeaters scattered on nearby hills.

This isn't to say they can't be a resource in SAR. Alameda County brought out a brilliant array of UAV equipment after the Camp Fire and were able to survey large portions of the burned town of Paradise and then process the imagery down to almost 1 cm resolution in their IC trailer. It really was some next-gen stuff and they did it way faster than the ground pounders could survey the same area. Down in the southwest, in specific types of terrain, drones are being used to quickly survey some popular holes that hikers find their way into. And, a drone scouted an orchard and found a lost subject there about a year ago.

But you have to weigh those successes against the much larger number of cases where people with hundreds of hours of experience can still very nearly step on top of a nonresponsive subject without seeing them. Finding lost people is hard, and many of the failures to find lost people have more to do with the problems of getting bad information into IC, or searching the wrong area, or the subject being in an inaccessible area, or the lost person's remains getting quickly predated by local wildlife.

Thermal imaging likewise just does not work the way that people think it does. It doesn't work in cold environments like the Sierra in winter (western or eastern), because people are typically wearing insulated clothing and the entire area around them is a gigantic heat sink. It also doesn't work in very warm environments or in heavily vegetated environments or rocky environments with sunlight -- rocks absorb and re-radiate heat and so do plants.

I've had this conversation a few times with different technologists. What we need is a balloon that we can put up with a big ol' repeater on it. That would provide a lot more immediate benefit for search operations. But, it's not sexy, so nobody's as interested as they are in trying to fly quadcopters over impossible terrain 20 minutes at a time.