|Quoting nupogodi (Reply 240):|
Quoting WarrenPlatts (Reply 238):
It has been shown by inspection that the flight paths are indeed consistent with a series of ping rings corresponding to the times of the various handshakes
You can't be serious. You've created a model to fit the data (which itself was based on a model), and then said, "Look! The model fits the data!"
I am absolutely serious. You simply don't understand what we tried to do: the two flight paths that Inmarsat published are not random lines drawn on a globe.
Notice how the 400 knot track curves to the left, whereas the 450 knot path is mostly straight. Why do you suppose that is? The answer is that the gradual curve to the left is necessary in order to be consistent with the series of ping rings. If you plotted a more or less straight track with a velocity of 350 knots, it would curve even more to the left.
So, I'll repeat:
1. distance = velocity * time. They told us the assumed velocities (400 & 450 kts) and gave us the position at 24:11. The next ping ring back was at 22:40--1.52 hours in the past. Thus: 450 * 1.52 = 683 nm and 400 * 1.52 = 607 nm.
2. Now we go back and measure back from the 24:11 line of position (LOP) along the respective tracks 683 and 607 nm.
3. Then we measure the distance from those two points to the subsatellite point and compare them.
4. Hmmmm. The distances to the subsatellite point are identical: 2199 nm. So what does that tell us?
5. That the two points 683 and 607 nm back from the 24:11 LOP are in fact lying on the same 22:40 LOP, or as Duncan prefers to call them "ping rings" or as Pihero prefers to call them "loci".
There's a little more to it than that (e.g., taking into account the movement of the satellite), but you should be able to get the general idea.
No one is claiming the ping rings are perfectly accurate. Just the precision of the time measurement (+/- 0.3 ms) causes an error on the order of 50 nm. Also, one refinement that has not been done is taking into account the actual shape of the Earth: we've been assuming a spherical Earth, and so that could cause another 10 or 20 nm error for the southern latitudes.
But still, compared to the whole Indian Ocean, that's quite a constraint. And it also places quite a constraint on what possible flight paths can look
like. E.g., a gradually curve to the left is consistent with an a/c flying in heading mode, and getting pushed by crosswinds. A straight path like the 450 knot path is consistent with a constant heading flight in track mode.
The problem is that the current search area is so far to the east: it is hard to draw a normal looking flight path that is consistent with the other ping rings. E.g., see below: I can modify my waypoint track with a sharp left turn at 2490S to reach the search area and still be consistent with all ping ring data, but it looks odd: Why the sharp turn that appears to be going nowhere in particular?
A more plausible, normal-looking path would be to simply follow route P627 to waypoint KALOX, and then route M641 to Perth--but it doesn't fit the ping ring data....
So don't be surprised if the underwater search turns out to be a wild goose chase....
You can download the Duncan Steel ping rings as kml files and load them directly into your Google Earth if you want. This is super easy, and beats the heck out of trying to plot them out by hand as I had done previously. The files are Ping_Ring_00_11.kml thru Ping_Ring_22_40.kml.