Both can be correct, each in his own inertial system.

There were too many things that they needed: The inertial navigation system, for one.

The A-10 began receiving an inertial navigation system in 1980.

"But inertial systems don't go anywhere near that kind of density."

An inertial navigation system measures every move of the plane.

Apparently, the inertial navigation system in my head was working fairly well.

In inertial systems it is equal and opposite to the light time correction.

I even had one case where the inertial navigation systems started acting up.

We'll be using our inertial navigation system to get us there.

The pole, according to the inertial navigation system, was three hundred kilometers away.