The Turn: North versus South:
If heading North a turn at 18:29 would not have been critical or necessary, but heading South such a turn would have been, as well as the earliest possible point when such a turn could have successfully been made to get around Sumatra and and evade Indonesian radar.
If heading North the plane could have continued on its westnorthwest heading for another 2 hours and 1100 miles to the Bay of Bengal when at any point it could then have turned North. In doing so it would not have been able to hit any of the Inmarsat arcs. This is the way Malaysian officials thought it went after their fruitless search in the South China Sea. The pilot’s maneuver at 18:22 to go dark and evade their radar was thus successful at conning them — and they are still reeling from it.
If it went North from N6.85E95.45 @18:29 to N34E82 @22:41 hitting the arcs along the way, it would have flown 2062 miles @491mph average with only that 1 turn of ~30 degrees at 1829.
But turning South at that point to its 2241 intersection is 2242 miles @534mph average with 2 turns: the first a big turn of ~90 degrees at 18:29 and the second lesser turn at 1941 of ~30 degrees.
Cruising speed of a Boeing777 is ~580mph. MH370 averages 557mph until the turn but then slows after the turn to 491mph North versus 534mph South.
Both require change in speed and/or direction at 22:41 to hit the 2411 arc. If it slowed down at 22:41 on the same heading it would hit Almaty Kazakistan N43.28E76.89 http://en.wikipedia.org/wiki/Almaty at 24:11 after another 693 miles @462mph average.
The speed factor, the autopilot factor, the radar factor, the satellite location factor, and the maneuver at 18:22 followed by Log On Request at 18:25 adn then the frequency burst at 18:29 all point to the turn South —
Nothing points North —
Near-conclusive evidence that Malaysia Airlines MH370 was hijacked: cockpit tampering deliberately hid plane from radar