I have a question - because I was initially confused and others might be too - when Inmarsat first suggested a North and South route, why does the 7th arc estimated landing site not mirror the estimated crash site in terms of North/South of the Equator? Wouldn't we expect a crash site direct South, sort of North East of and nearer to the French Southern and Antarctic Lands / Heard Island and McDonald Islands than what is stated?
That's a really good question and a fairly subtle one! It turns out that the northern and southern routes are symmetrical not along the equator, but along a line drawn from the subsatellite point to the point of north/south divergence, which was around 10 degrees north. This effectively rotates everything counterclockwise on the 7th arc: the southern endpoint is further north and east, and the norther endpoint is further north and west.
I have a question - because I was initially confused and others might be too - when Inmarsat first suggested a North and South route, why does the 7th arc estimated landing site not mirror the estimated crash site in terms of North/South of the Equator? Wouldn't we expect a crash site direct South, sort of North East of and nearer to the French Southern and Antarctic Lands / Heard Island and McDonald Islands than what is stated?
That's a really good question and a fairly subtle one! It turns out that the northern and southern routes are symmetrical not along the equator, but along a line drawn from the subsatellite point to the point of north/south divergence, which was around 10 degrees north. This effectively rotates everything counterclockwise on the 7th arc: the southern endpoint is further north and east, and the norther endpoint is further north and west.