  The flyby anomalies are unexplained velocity jumps of 3.9, -4.6, 13.5, -2,
1.8 and 0.02 mm/s observed near closest approach during the Earth flybys of six
spacecraft. These flybys are modelled here using a theory that assumes that
inertia is due to a form of Unruh radiation, and varies with acceleration due
to a Hubble-scale Casimir effect. Considering the acceleration of the craft
relative to every particle of the rotating Earth, the theory predicts that
there is a slight reduction in inertial mass with increasing latitude for an
unbound craft, since near the pole it sees a lower average relative
acceleration. Applying this theory to the in- and out-bound flyby paths, with
conservation of momentum, the predicted anomalies were 2.9, -0.9, 20.1, 0.9,
3.2 and -1.3 mm/s. Three of the flyby anomalies were reproduced within error
bars, and the theory explains their recently-observed dependence on the
latitude difference between their incident and exit trajectories. The errors
for the other three flybys were between 1 and 3 mm/s.
