Not a pilot, but a scientist who stumbled across this discussion. :-) I doubt anyone is watching this thread anymore, but here's a perhaps more intuitive answer.
The circumference of Earth at the equator is roughly 40,000 km. Earth rotates once per day, so a point on Earth at the equator travels 40,000 km in 24 hours, or has a speed of about 1600 km/hr. The circumference of Earth at 60 deg. N. latitude is half that: roughly 20,000 km. But, a point on Earth at 60 deg. N also completes 1 rotation in 24 hours, so its speed is about 800 km/hr.
Now, say you fly south from 60 deg. N to the equator. You are departing from an airport that is moving to the east at 800 km/hr, but your destination is moving to the east at 1600 km/hr. If you fly directly south, when you reach the equator you will be thousands of kilometers to the right (west) of the airport. Once airborne you are no longer in contact with the ground, and as you fly south the ground beneath you is moving increasingly faster to your left.
Over small distances north and south this difference is minimal and, I'm guessing, very small compared to more routine navigational considerations and corrections. But for long flights north or south the correction is a necessity and--I'm guessing again :-) --probably computed by navigation software w/o the pilots ever seeing it. Again, not sure about the piloting parts--but the Coriolis stuff is correct., fwiw.