Vector Solution for the intersection of two Circles of Equal Altitude
Andrés Ruiz González - Navigational Algorithms - http://www.geocities.com/andresruizgonzalez

GP1	0.999923847578223	0.000076152421810	0.012340714937586
GP2	0.707011424752991	-0.706986745829293	0.017452406437283
alpha	44.999000152306770
k1	-0.000017451091068
k2	0.707119121186716
OIc	0.499923847578177	-0.499923847730409	0.012340714943585
l1	0.707106781078880
l2	-0.707106781078880
GP1xGP2_unit	0.012340714937586	-0.012340714945826	-0.999847695156345
I1 xyzBL	0.508650050793906	-0.508650050951964	-0.694658370347556	-43.999999991123651	-45.000000008902106
I2 xyzBL	0.491197644362449	-0.491197644508854	0.719339800234726	45.999999991428218	-45.000000008538727