It should mean both. They need to learn how to do it by hand and then learn how to lean on a navigation system. If only GPS fails, then the celestial navigation program fallback runs without a hitch. If shit hits the fan, then they can break out the manual and remember how to do it by hand.
alt Hacker News
It should mean both. They need to learn how to do it by hand and then learn how to lean on a navigation system. If only GPS fails, then the celestial navigation program fallback runs without a hitch. If shit hits the fan, then they can break out the manual and remember how to do it by hand.