Gary loves to make this seem like a simple math problem, but it really isn't. These charts are a guide that was developed to help manage a search, they do not in themselves constitute the search. The kind of searches they were developed for was missing aircraft such as the example given, as the USAF figured out that they really did not have anything in their inventory that could do a good job searching, so they gave the job to the CAP. I do not think the POD chart was developed for looking for missing persons, although it can be a tool used to do so.
The thing about missing airplanes is that they generally leave some sort of trace, fire, smoke, smoking hole, broken trees, aluminum debris field, disturbed snow, vultures gathering - something that can be seen from farther away than a single person can be seen. That's why the search visibility in the POD Chart starts at 1 mile, it was developed for missing airplanes and the signs they leave. Gary likes to quote my sample that uses the 1mi visibility, which is probably reasonable if we're looking for the Electra or perhaps a VW. However, in this case we're talking about looking for a person who is not necessarily out in the open, and I don't think a 4 mile, or even 1 mile search visibility is reasonable. I would not use those values if I were managing an actual search for a missing person in heavy cover.
Instead, I would use a less than 1mi search visibility and extrapolate the values of the POD chart to accommodate. Why? Because I don't believe that it is reasonable to say that anyone can see and recognize a person on the ground in heavy tree cover from a height of 500 ft from a mile away. The trees in the way would prevent you from seeing the person, all you end up seeing is the canopy. In effect, you have to be right on top of them to see them.
Gary on the other hand, believes he and our Navy fliers (apparently untrained in any SAR technique) can see and recognize a person on the ground under the tree cover from 4 miles away. He apparently has very good eyes.
A good case in point is found in the aerial tour
http://www.youtube.com/watch?v=DL9FGsvB3E8&feature=youtu.be where if you freeze frame the flight at 5:30 you will find that it is extremely difficult to see the three persons in the video, even though you are flying at less than 200 ft, and within about .2 of a mile from them. Note that the single person who is subsequently visible, only becomes so when the camera (who knows where they are) zooms in on them. And even then, only one out of three can be found.
As each of you evaluate this, what is your search visibility at this point, when you cannot see and recognize three persons on the ground? Is it appropriate for you, as search manager, to be using a 4 mile search visibility, or even a 1 mile search visibility for this search? I think not.
Gary prefers to go in that direction as it suits his argument that AE was never on Nikumaroro, and if she had been, the Navy would have seen her in their few passes over the island with their 2 man untrained in SAR crews flying open cockpit biplanes. If the Electra was lying on the beach, I would agree with him.
If Gary was hired to argue the case of CAP pilot sued by the grieving spouse of a pilot who wasn't found during a search, he'd be arguing the other way and describing how difficult such searches can be. He likes to portray things as black and white simple, because that makes it easy for juries to make a decision. Apparently, he's pretty good at it.
But, as usual, things are rarely black and white simple. You can judge this for yourselves. Look at Bill Carter in the aerial tour video, the guy in the white shirt. I can almost guarantee you that he, along with everyone else on the ground that day, has scrambled as best he can to get to a place "out in the open" where he can see the helicopter, he's between trees, and as far as he is concerned, he thinks he's easily visible. Bill is not hidden away under a tree, but he is in the shadow of the tree, so even though there are areas that are clear, that doesn't mean that a person in the clear area is easy to see.
If you look at the fly by the 7 site, even with the camera lens zoomed in, you cannot see the 3 to 4 persons who are ashore - not the three guys headed out into the lagoon - but several additional folks back in the bush. You have to ask yourself if there is really 30% probability of seeing persons on the ground in a single pass?
If you stop the video at 11:55, before the camera zooms in, the helicopter is approximately .75 nm from the 7 site, yet the three people who are out in the lagoon, wading in the open, are not recognizable, nor for that matter is the 21 ft red color rubber Naiad boat they are wading to, and they are all as out in the open as they can possibly be.
For the CAP, I've sat a target consisting of the major parts of a Cessna 152, set in a small clearing in the tall pine trees of Colorado, with a practice ELT beacon going. Several trained SAR crews failed to visually spot me even when they pretty much knew the target was localized to one ridge. Again, they had to be right on top of me to see me from the right angle.
You'd think that something that looks like the photo below (if I can get it inserted) would be easy to find, but it wasn't.
So we can go on arguing about what the probability was, or the search visibility to use, but in the end it really won't solve anything. My experience in SAR tells me that the probability, given the scenario, was pretty low, and I don't think that the POD tables are going to somehow mathematically get us there.
Andrew