Malaysian Airlines MH370 contact lost

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For anyone wishing to explore exactly where the inmarsat "arcs" are located.
This is a detailed description of how to use Google Earth to do it.
No speculation, no hypotheses. Just instructions, and a table I have calculated to take into account the distance of the satellite.
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Detailed Instructions:

We can't know how accurate the 40 degree ring is. Its probably been rounded, measurement accuracy is uncertain, final position of MH370 may be an uncertain distance away.

But it seems to be the solidest thing we have, and the Aussies seem to believe in it, as their new search area is bang on.
Using Google Earth, you too can explore exactly where such Inmarsat "arcs" go, using the "ruler" in "tools" at the top.

Proceed thus:
Search for the point directly below the IOR satellite, by entering "0N 64E"
Now open the little ruler window. Do this by finding "Tools" at the very top, and clicking "Ruler"'
In the little ruler window, choose "Line" at the top, and set units to "nautical miles"
Go back to the map…you'll see a bigger squarish cursor.
Click on the point 0N 64E, which should be in the middle, this sets the start of the ruler line.
Now zoom out (mouse wheel) to see up to (say) asia. Drag the cursor (say) North, making a line. Make it 2600nm long. This point is on the 40 degree arc.
You can still zoom and scroll the map normally, the ruler line will stick to your cursor.
Now feel free to explore where the line ends, keeping its length about 2600nm long.

And of course you can drag down south to explore the southern arc. Just remember 2600 nautical miles.

Clicking will freeze the line, so you can scroll about etc, but it can still be picked up and moved more by clicking its end point (a hand appears). The "save" button will make the line permanent (and unchangeable). Any other click deletes it. After saving, you can draw another line.

Now you can estimate for yourself how far MH370 might have deviated away from the given final 40deg ping arc, and factor in your own uncertainty, by increasing or decreasing the 2600 value..

You could even explore your theories of likely distance travelled, by doing a similar thing from whatever start point you like, using "path" instead of "line. This will not delete your previous line to the arc.

So why 2600 nautical miles? Not 3000, as another poster suggested?
I have corrected for the distance to the satellite, instead of assuming it infinitely high.
Here is a table of distances for other arcs.

Angle Distance (nm)
10 4284
20 3708
30 3147
35 2871
39 2653
40 2599
41 2545
45 2330
50 2064
60 1539
70 1021
80 509

PM me if you would like to check the formula I have derived. My qualifications to do so include both science and maths degrees - though in fact schoolboy trig is all that is required.

All this does assume that the satellite is truly stationary above the earth. Orbital variations are I think unlikely to introduce an error of more than 60 nautical miles.