Smith lake is a possibility, but it's a few miles west of the the FBI flight path. you also have to justify the time frame in order to prove he dropped into the lake. the whole area is suspect in my opinion. the plane crosses Hayden island on the east side.
That's actually not a bad idea IF you can stretch the timeline. It is clearly in the Columbia drainage basin.
Never said it wasn't, but it's a little further west. you need to justify the plane that far west. Carr gives a time frame past this position. all the water in this area is what I've been stating for a while now. if one chooses to accept he jumped in the area of the Columbia, all of these water holes become potential targets for landing.
If the timeline is inaccurate, are we strectching anything? 
The one almost certain 'weak link' in whatever flight path you chose, assuming the Eastern Washougal route never happened, is the timeline. Depending on whose version you accept the time and position of "8:05" is a benchmark and central to everything else. Why? Because Rataczak pins everything to his last communication with Cooper at 8:05, whatever their position was when 8:05 happened. (If I understand this matter correctly, almost everyone accepts a plus/minus 1 minute error in the Transcript timeline).
So, the issue if when did he bail after 8:05 and where were they when that happened.
It's on that issue that we have differing accounts and there is literally nothing in the Transcript to clarify this. All Rat says is "5 to 10 minutes after 8:05". If the Anderson interviews are real, Anderson says it had to be later than Rat says because "we discussed it and nobody had called it in yet!". "We waited", Anderson says. Cooper called in again at least once
after 8:05 and asked the plane to be slowed and stabilized. All of the above is eating time after the benchmark 8:05. The key event is the "pressure event - bump". When exactly did that happened and when was it reported ...
The FBI etal places his estimated jump at 8:11. Anderson, if his interview is real, says 8:12 to even 8:16 is not an unreasonable estimate given everything else and the "confusion-delay in reporting" that was going on at the time.
If you extend the jump time to something beyond 8:11 now we are getting close to the Columbia River basin system which could bring Cooper money to Tina Bar by natural means.
There is "no" reason to believe the money arrived on Tina Bar by any other means! Therefore, the flight path, drop time & position, and the money at Tina Bar are all connected by facts of causation. One thing caused the other. It's old fashioned physics.
One thing that strengthens the idea of "causation throughout this hijacking" for me, is Cooper himself. This was a fairly well managed hijacking as hijackings go, with not too many lose strings and unexpected events, with Cooper delivering messages continually to the cockpit managing just about every facet of this hijacking he could control including slowing and stabilising the plane to accommodate a jump, right up to the time he jumped (according to Anderson).
That level of management strengthens the whole notion of Causation working throughout this hijacking which then explains all of the physical facts of the crime from the placard on the ground near Toutle to the money at Tina Bar, all connected to the general timeline, flight path options, and Cooper specific actions resulting in evidence on the ground.The crime and the events of the crime are simple, in my estimation. The personalities looking at the crime is what has become very complex. This crime and what happened is not rocket science - just the opposite! It is the people dealing with this crime and the lack of direct data available, that has lead to complexity, and 99.999% of that has nothing to do with the facts of the crime itself or with Cooper himself.
There isn't an un-natural event in this whole story. The whole thing is "by natural means" and that includes Cooper himself on that plane.
This whole story is a textbook case of classical Causation in action, from start to finish. I have yet to see one un-natural fact in this whole case ... if we had all of those facts!
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