Sure a helicopter can cover more area, but since they have found less than 1% of lost hikers in NH even after their multiple passes their actual POD is more like .0001%. POD for an individual ground searcher is also low but they're a lot cheaper particularly if volunteer.
The advice to make yourself visible to aircraft is excellent, this may include tossing something bright over a tree branch when stopped or leaving arrows in open areas if you are moving. A while back there was a note on whether a lost hiker should stay put, go downhill to road, or go uphill for better cell coverage with no firm answer. Certainly in the recent case, the guy was found sooner by walking himself out and the expensive helicopter was of no use at all.
That may not be exactly correct.
We would need to know if in every instance the area that they had the helicopter search, the subject was there at that time. I do agree with you though that 30% is usually a high figure for Helicopters more typical of areas out west. It was just an example. The effort expended by the helicopter is what allows it to search areas multiple times regardless of how difficult the terrain is.
But, night searches with FLIR and NVD's and the use of a ground laser or very visible ground fires would make significant differences. One is good, two is better but three small ones are best, again, increasing your footprint. Day searches with the subject able to generate signal flashes or smudge signals will greatly increase the effectiveness of aircraft as well.
If the helicopter is being used to search alpine areas I would think that the POD
could be around 30%. But the subject would need to actually be in that area.
NVD's are very effective in the infrared range. They even use IR sources to help illuminate areas when there is no ambient light. IR sources are very, very visible at very long distances. I have personally seen tanks illuminate their targets with IR searchlights at distances of well over a mile. At that was with second gen NVD’s. I have seen small IR sources like cigarettes at long distances also but I can’t say I have seen them a mile away.
When I was in I was doing everything I could to stay hidden, not trying to be seen.
FLIR (forward looking infrared) came about because of the militaries need to generate no radiation at all on the battlefield and still be able to see at night. The Starlights (NVD’s) needed IR illuminators in total darkness as did the old IR systems that also used large IR illuminators. Not healthy on the battlefield.
Even the thermal imagers that Fire departments use can be used in a search role fairly effectively.
EDIT: I should also point out that it isn't always an intention to find something or someone. It is sometimes the intention to exclude an area (low POA) from needing to be searched by limited ground resources.
Just my thoughts.
Keith