The 1 in 60 rule is the single most useful piece of mental maths in EASA ATPL General Navigation. Learn it once and it pays off in Gen Nav, Flight Planning, Radio Navigation and even your instrument approaches.
Here is what it is, why it works, and how to apply it fast under exam pressure.
What the 1 in 60 rule actually says
If you travel 60 nautical miles and end up 1 NM off your intended track, your track error is almost exactly 1°. It is a small-angle approximation: at 60 NM, 1 NM subtends roughly one degree.
That single relationship scales. Off by 2 NM after 60 NM? About 2° of error. The rule turns a geometry problem into arithmetic you can do in your head.
The formula you need to memorise
To correct your heading back onto track you work with two angles:
- Track Error (TE) = (distance off track ÷ distance gone) × 60
- Closing Angle (CA) = (distance off track ÷ distance to go) × 60
- Total correction = TE + CA — this returns you to track at your destination
Turning by the track error alone only makes you parallel the original track. To actually regain it, add the closing angle.
Worked example 1 — regaining track
You have flown 30 NM along a 90 NM leg and find yourself 2 NM right of track.
- Track Error = (2 ÷ 30) × 60 = 4°
- Distance to go = 90 − 30 = 60 NM, so Closing Angle = (2 ÷ 60) × 60 = 2°
- Total correction = 4 + 2 = 6° left to be back on track at the destination.
Worked example 2 — a fast drift check
After 20 NM you are 1 NM left of track. Track error = (1 ÷ 20) × 60 = 3°. Turn 3° right to parallel the track, or more to regain it. No plotter, no CRP-5 — just arithmetic.
It is not only for navigation
The same 1-in-60 logic underpins several other exam favourites:
- Descent gradients: a 3° glidepath is about 3 × (1/60) ≈ 5%, or roughly 300 feet per nautical mile.
- Rate of descent: for a 3° path, ROD ≈ groundspeed × 5. At 120 kt groundspeed that is about 600 ft/min.
- VOR/ILS deviation: estimating how far a given dot of deflection puts you off the centreline at range.
Common mistakes EASA students make
- Mixing up distance gone and distance to go. Track error uses distance gone; closing angle uses distance to go.
- Stopping at the track error. That only parallels the track — you must add the closing angle to regain it.
- Using it on large angles. The approximation is excellent up to roughly 20–25°. Beyond that the small-angle assumption breaks down.
- Unmatched units. The off-track and along-track distances must be in the same unit before you divide.
How it shows up in the ATPL exams
You will meet the 1 in 60 rule directly in General Navigation track-correction questions, and indirectly in Flight Planning (descent profiles), Radio Navigation (deviation at range) and Performance (climb and descent gradients). Examiners like it because it rewards the candidate who can reason quickly rather than reach for a calculator.
Practise it until the arithmetic is automatic. Under time pressure, a five-second mental estimate frees your minutes for the questions that genuinely need them.
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Frequently asked questions
What is the 1 in 60 rule in aviation?
It is a small-angle approximation stating that an aircraft 1 NM off track after 60 NM has a track error of about 1°. It lets pilots calculate heading corrections quickly without instruments.
How do you calculate track error with the 1 in 60 rule?
Track error in degrees = (distance off track ÷ distance gone) × 60. To regain track by your destination, add the closing angle: (distance off track ÷ distance to go) × 60.
How accurate is the 1 in 60 rule?
It is very accurate for angles up to about 20–25°. Beyond that the small-angle assumption weakens and the calculated angle increasingly understates the true angle.
Where is the 1 in 60 rule used in the EASA ATPL syllabus?
Mainly in General Navigation for track correction, and in Flight Planning, Radio Navigation and Performance for descent gradients and deviation estimates.
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