My goodness, brought that thread to a screeching halt didn't I?
I have said that the CAB investigators seem to have been held in low regard by Lockheed and Northwest. Evidence for Northwest's view is documented in Don Nyrop's letter. Evidence for Lockheed's view comes from the flight path map. I owe Lockheed a word of appreciation here.
When a reader first suggested I look at turn and bank calculations, I started by overlaying the CAB map with circles to measure the turn radius at different points. I said that not all who drew the map would have been thinking of my reverse-engineering their work. When the CAB report said that Lockheed held the inner curve to be the only possible path, it didn't dawn on me until much later what that signified.
To say that this was the only possible path is a remarkably assured statement. It does not sound like Lockheed was simply more discerning in its choice of witnesses to believe, which might have resulted in a statement of heightened confidence but certainly not one of such bald certainty. And no other means of recording the flight path is mentioned in any report.
The only reasonable explanation for Lockheed's statement is that the team calculated the path. I have no direct evidence, but I will assert this. With slipsticks and pencils they ran iterations just as I did with an Excel spreadsheet, and they kept on until they had derived a path that ended at the impact point.
When they had finished the path calculation, they said they had found the only possible one. When I ran the Excel routine I came close to the same path. When I flew the simulator I came up within a wingspan of the same path. Lockheed knew it was the only path not because witnesses agreed but because they ran the math.
This means that Lockheed knew the plane hit at much less than a vertical bank. The Lockheed team would have known how debris was distributed, and if I am correct that engine four was left at the tracks then Lockheed knew the plane hit at no more than 35 degrees.
The inner curve on the map was not something drawn by a draftsman with a French curve, nudging and tweaking while a bunch of guys looked over his shoulder until they had a consensus. It is the plot of their turn and bank calculations. The CAB's giant looping flight path range, trowelled on top of Lockheed's calculations, must have been like a slap in the face.
The inner curve is like a hand print in cement; it memorializes Lockheed's presence. It is evidence that due care was taken by at least some of the investigators, and it's a permanent record of what the Lockheed team was thinking.