Transport & Manufacturing
Aviation Top of Descent (3:1 Rule) Distance & Rate of Descent (FPM)
Calculate aviation top of descent (3:1 rule) distance & rate of descent (fpm) using the stated engineering or scientific relationship and adjustable field inputs.
Preparing your result…
What this calculator does
Calculates Aviation Top of Descent (3:1 Rule) Distance & Rate of Descent (FPM) using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
3:1 rule: descent distance (NM) ≈ 3 × altitude to lose (ft) ÷ 1,000; rate (ft/min) = altitude ÷ (60 × distance ÷ groundspeed) ≈ 5.56 × GS
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • 3:1 planning rule: descent distance NM≈3×altitude to lose(ft)/1000. At constant groundspeed, time min=60×distance NM/GS(knots), so descent rate ft/min≈5.556×GS(knots).
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • Specify altitude units and add the rate output. The 3:1 rule is approximately3.14°, not exactly3°; an exact3° slope needs about318.4ft/NM and rate≈5.31×GS. Account separately for deceleration, wind/groundspeed changes, restrictions and aircraft performance.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Altitude to lose (ft) | Groundspeed in the descent (kt) | Start descent this far out |
|---|---|---|---|
| Worked example | 8,000 | 140 | 24 NM |
| Half the amounts | 4,000 | 70 | 12 NM |
| Double the amounts | 16,000 | 280 | 48 NM |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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