LostXOR

Seems some people think accuracy is limited. That’s not the case. From the article:

Immediate access to satellite measurements and navigation results is disabled when the receiver’s velocity is computed to be greater than 1000 knots, or its altitude is computed to be above 18,000 meters. The receiver continuously resets until the COCOM situation is cleared.

The limitations are enforced by the GPS receiver itself. You can buy “unlocked” GPS modules without these limitations, but they’re harder to get ahold of.