# 1 in 60 rule for VORs

I'm working on some math questions for a CPL exam (not the FAA written), and I am curious about the 1:60 rule. How does that math work out? I know that if you're 60 NM from the station and 1 NM off course, you're 1 degree off course. How does this work out for other angles? I'm also wondering if this is the same rule used to derive the VOR time/distance formulas.

Any insight would be helpful, along with derivations of the formulas. I'm just having trouble picturing everything in my head.

Thanks!

For example, we can take the sine of 1 degree, and multiply it by the 60 NM flown, to verify the 1:60 rule. We would plug $$60 \, \text{NM} \times \sin(1°)$$ into a calculator, and the result would be 1.05 NM - very close to the rule of thumb.
• So for very small angles you have $\sin (n°) \approx n / (180/pi) \approx n / 57.3$, but as the angle gets bigger that approximation is a little too high, so it makes sense to use a constant that's a bit bigger than 57.3. 60 has a lot of factors so it's easy to do the mental math. Apr 24 at 14:27