The 1 in 60 Rule — Page 199, Lesson 173

I want to walk you through a very practical mental-math tool that pilots use in the air — it's called the 1 in 60 Rule. This rule gives you a quick way to convert a distance off track and a distance gone along track into an angle, specifically your track error angle in degrees. Here's the idea. If the numbers don't lend themselves to simple mental proportioning — meaning you can't easily do the ratio in your head — there's a formula. Let me write it out for you: z = (distance off / distance gone) × 60 Where: - z is the track error angle in degrees, - distance off is how far you are to the left or right of your intended track, in nautical miles, - distance gone is how far you've travelled along your track from your departure point, also in nautical miles. Let's work through the example they give. You find yourself 6 miles right of track after having flown 40 miles along track. Plug those numbers in: z = (6 / 40) × 60 Now, 6 divided by 40 is 0.15. Multiply that by 60, and you get 9 degrees. So your track error angle is 9° to the right. That's the core of the 1 in 60 Rule. The name comes from the fact that if you are 1 mile off track after 60 miles flown, the angle is 1 degree — because (1/60) × 60 = 1. It's a simple linear approximation that works well for small angles. Now, the excerpt then moves into a set of practice questions. These are the book's practice questions — let's try them one at a time.