When you first boot the system up, it spends about 5 minutes measuring the rotation of the Earth. For this reason, you can’t reset it when in motion.

That’s very interesting. I’ve heard a lot about IRS/INS, but I didn’t know what it was doing during initialization.

It must be an extremely sensitive instrument if it can measure the rotation of the Earth. I’m wondering, does anyone in the cockpit have to sit still when it boots up? Because I can imagine walking around in the plane alone, or even just a powerful sneeze would already introduce some movement, not to talk about the ground handlers loading the cargo.