061 General Navigation topic guide
The 1 in 60 Rule
The 1 in 60 rule is a small-angle shortcut: over a distance of 60 units, 1 unit of displacement subtends very close to 1 degree at the point you started from. Because ATPL track errors are typically a handful of degrees, not tens of degrees, that approximation is accurate enough to replace a full trigonometric calculation with simple division, which is exactly why it survives as the standard mental-arithmetic tool for airborne navigation.
The rule produces two related angles from a single fix: the track error already accumulated, and the closing angle still needed to converge on a point ahead. Added together, they give the single heading alteration that flies the aircraft directly to the original destination from wherever it actually is now, rather than merely back onto the original track line.
Where the approximation comes from
At a range of 60 nautical miles, an arc of 1 nautical mile corresponds almost exactly to an angle of 1 degree, because the tangent of a small angle in radians is close to the angle itself, and 1 divided by 60 is close enough to the radian measure of 1 degree for navigation purposes. Scaling that relationship gives the general rule: an offset of D nautical miles after flying a distance of N nautical miles represents an angular error of D divided by N, multiplied by 60, in degrees.
The approximation loses accuracy as the angle grows large, which is why it is taught and examined for the modest offsets and corrections typical of dead reckoning, not for angles approaching a right angle.
Track error, closing angle, and correcting to the destination
Track error is the angle between the heading actually flown and the track that would have taken the aircraft to where it now is: track error (degrees) = distance off track, divided by distance already flown, multiplied by 60. Closing angle is the angle still needed, from the present position, to converge exactly on the original destination: closing angle (degrees) = distance off track, divided by distance still to run, multiplied by 60.
To fly directly to the original destination from the present fix, add the two angles together and turn through that total, back towards the track. To instead regain the original track itself, rather than cut the corner to the destination, use the double track error method: turn through twice the track error, hold that heading until back on the original track line, then turn back by the original track error to resume the original heading, now flying parallel to, and on, the original track.
- Track error (degrees) = distance off track / distance flown x 60
- Closing angle (degrees) = distance off track / distance to run x 60
- Correction to fly direct to destination = track error + closing angle
- Correction to regain track (double track error) = 2 x track error, then back by the track error
Worked example
Worked example: correcting directly to the destination
Not quite. The correct answer is C.
Correct answer: C
- A. This is the track error alone. It corrects for the drift already made but ignores the further angle needed to converge on the destination from here.
- B. This is the closing angle alone. It converges on the destination from a point assumed to be on the original track, ignoring the 4 NM of track error already accumulated.
- C. Correct: track error (4 degrees) plus closing angle (6 degrees) gives the full 10 degree correction that points the aircraft directly at the destination from its present position.
- D. This has the correct magnitude but the wrong direction. The aircraft is right of track, so the correction must turn it left, back across the track; turning further right doubles the error instead of removing it.
Step by step
- Track error: distance off track over distance flown, multiplied by 60: (4 / 60) x 60 = 4 degrees.
- Closing angle: distance off track over distance still to run, multiplied by 60: (4 / 40) x 60 = 6 degrees.
- Total correction to fly directly to the destination from the present position is the sum of the two angles: 4 + 6 = 10 degrees.
- Direction: the aircraft is to the right of track, so the correction turns it left, back across the original track and on to the destination in one turn.
- Sanity check: the closing angle alone (6 degrees) would only be correct if the aircraft were already back on the original track at this point; adding the 4 degree track error accounts for the fact the 4 NM offset still has to be closed as well, which is why the two angles are added rather than either one used alone.
Common mistakes
Using only the closing angle and forgetting the track error already flown
The closing angle alone assumes the aircraft is still on the original track at the moment of correction; skipping the track error term under-corrects and the new heading still misses the destination.
Turning the wrong way, away from the track
The correction always turns the aircraft back towards the side it drifted from. Applying the right magnitude in the wrong direction increases the total error instead of removing it, and is exactly how the mirrored distractor is built.
Confusing the direct-to-destination correction with the double track error method
Correcting straight to the destination uses track error plus closing angle; regaining the original track line uses twice the track error instead. Applying the wrong one of the two gives a numerically plausible but conceptually wrong heading.
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Last reviewed July 2026