lets calculate the kinetic energy:
ek = (1/2)*45000*(260*1000/3600)^2 = 117.36 x 10^6 J
from the definition of magnetic force we have:
F = Bqv
where F is the force, B is the magnetic field, q is the charge of the body, v i s velocity of the body.
The aircraft is going through a circular motion with radius equal to the radius of the earth plus the aircraft altitude, lets call all that radious r, therefore the aircraft feels a centripetal force:
F = mv^2/r
hence we can equal the magnetic and centripetal force:
Bqv = mv^2/r
we can solve for the magnetic field:
B = mv/rq
hence the intensity of the strength of the magnetic field is expressed in terms of the amount of charge q contained in the aircraft and the total radius of the circular motion.
B = (45000)(260*1000/3600)/rq
B = (1/rq) * (3.25 x 10^6) Teslas