He probably refers to the effect of earth rotation in inertial systems.
You can consider stars as being fixed in space. If you have a gyro or an IRS which keeps aligned with a star, so to speak, you can navigate. But you have to take into account earth's rate. And transport rate, too, as said above, but this effect is due to earth's shape.
Take a look at all the gyro stuff, you will find it there.
The other effect he could refer to is Coriolis force, which is also due to earth rotation. There is a recent thread about it with plenty of interesting posts. However in the end I still have some doubts...