Off-course correction (1-in-60)
How far you have drifted off track, the turn to parallel your course, and the turn to reach your destination, exactly and by the 1-in-60 rule.
Planning and education aid. Not for primary navigation. Full disclaimer
Experimental: not yet fully verified. How results are checked
Turn 7.63° back toward the course to reach your destination, or 3.81° to parallel it.
- Turn to reach the destination by the rule
- Track error, and the turn to parallel
- Track error by the rule
- Closing angle
- Closing angle by the rule
Provenance
- Computed by
- aviation.wind.one-in-sixty 1.0.0, core 0.1.0
- Model
- Track error = atan(off ÷ flown); closing angle = atan(off ÷ remaining); turning by the track error parallels the course, and by the sum reaches the destination. The 1-in-60 rule takes 1 NM off in 60 NM as 1°, so each angle ≈ 60 × off ÷ distance (PHAK, navigation)
- Accuracy
- The exact angles are flat-plane geometry, fine for legs of a few hundred miles. The rule reads small (tan θ ≈ θ in radians, and 60 ≈ 57.3): about 5% high under 10°, and further off above 20°
- Notes
- 1 shown with the answer
- Cites
- Federal Aviation Administration, Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: Track error = atan(off ÷ flown); closing angle = atan(off ÷ remaining); turning by the track error parallels the course, and by the sum reaches the destination. The 1-in-60 rule takes 1 NM off in 60 NM as 1°, so each angle ≈ 60 × off ÷ distance (PHAK, navigation)
Show your work
Track error
track error = atan(off ÷ flown)atan(4 ÷ 60)= 3.81° (rule: 4°)Closing angle
closing angle = atan(off ÷ remaining)atan(4 ÷ 60)= 3.81° (rule: 4°)Turn to the destination
turn = track error + closing angle3.81° + 3.81°= 7.63°
The same steps an agent gets from the MCP server with explain: true.
Accuracy: The exact angles are flat-plane geometry, fine for legs of a few hundred miles. The rule reads small (tan θ ≈ θ in radians, and 60 ≈ 57.3): about 5% high under 10°, and further off above 20°
Worked example: 4 NM off course after 60 NM, with 60 NM to go. Source: add-aviation-suite 1-in-60 scenario: track error 3.81° (rule 4°), turn to the destination 7.63° (rule 8°). It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- Distance flown
- 60 NM
- Distance off course
- 4 NM
- Distance remaining
- 60 NM
You get
- Turn to reach the destination
- 7.63°
- Turn to reach the destination by the rule
- 8°
- Track error, and the turn to parallel
- 3.81°
- Track error by the rule
- 4°
- Closing angle
- 3.81°
- Closing angle by the rule
- 4°
Review: Not yet independently reviewed by a flight instructor (CFI).
Last verified: 2026-09-19, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 8 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Federal Aviation Administration, FAA-H-8083-25C. Navigation chapter (dead reckoning, off-course correction, and the 1-in-60 rule).
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.