Well this has been an interesting few months. In August I was finishing what I thought would be my last report version, planning to publish in September. To tie up loose ends, I wanted to correlate a newspaper description of prop ground strikes to my overhead view. The ALPA mentioned prop strikes too, but I had no idea what I was looking for. The newspaper was very specific about the location, so I magnified that part of the image and it pretty much blew me away. The large scar that I'd taken for a scrape mark was prop hits. To me it had looked like a scrape across the furrows of a plowed field. That's what I get for thinking like a farmer.
I laid it out on my virtual terrain and measured it. The mark is about 110' long, and it starts about 380 feet from the embankment. So this seems to be the next hit mentioned by the CAB and the distance is right. This tells us a whole bunch about the plane at that point.
First, it can only have been the number three prop. The ALPA says four was lost at the embankment and the prop marks came from three. The ALPA also said the plane was almost inverted at that point, which is ridiculous, and which is why I had dismissed this pretty completely. The marks can't feasibly be from one, or the plane would have been in a left bank. It can't be two or we'd see marks from one as well. Obviously I no longer think three was lost at the tracks.
Second, the marks are left on ground that slopes down to the west at about 1.5 degrees. The number three prop has about six feet of blade before the nacelle bottom is on the ground. For the plane to lose six feet or less of blade over a distance of 110 feet means it is descending at no more than about 3.5 degrees. Taken together, this means the plane was dropping at no more than five degrees. So here we have evidence that nearly 500 feet beyond the embankment the plane is still dropping on about the same five degree slope it had for about 300 feet before the embankment. There is nothing ballistic about this.
Third, there is no obvious scar left by the right wing to the right of the prop marks. This means again that the plane was in a max 35-ish degree bank. If the prop was being destroyed over this 110 feet, and still no wingtip scar, then the plane must have been approaching level by the end of that sequence.
Fourth, this means the breakup of the forward fuselage happened much faster than I'd thought, and in a tighter space. The remains of the forward fuselage came to rest about 120 feet past the last prop strikes, and of course it was leading the props. So it went from about 150 knots to stopped in a hundred feet. The engines went very little farther, so everything that broke off in this impact stopped in a remarkably short space.
To get my head around this so I could describe it, and to generate illustrations for my next report, I had to redo the impact animation. This was very unpleasant, as you might imagine, so I took a couple months off. I've posted the new animation on Youtube as
.