Grass Strip Landing Distance Calculator
Turf landing corrections with the twist nobody expects: dry grass lengthens the roll, but the right technique on firm turf barely notices — wet grass is the real trap.
The paradox of turf: rolling resistance that fought your takeoff now helps you slow — but only until the grass is wet, when the blades become a lubricant layer and wheel braking quietly resigns. UK CAA factor for wet grass: up to 1.6.
Formula
⚠️ Planning estimate only — your POH/AFM performance charts are the authoritative source. Always verify with official data, and apply your operator's safety factors. Not for airworthiness decisions.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Turf landing corrections with the twist nobody expects: dry grass lengthens the roll, but the right technique on firm turf barely notices — wet grass is the real trap.
About Grass Strip Landing Distance Calculator
Grass landings carry a friendly reputation — soft on the gear, forgiving of a firm arrival — that conceals a sharp asymmetry: dry firm turf adds only ~15% to the roll (its rolling resistance even helps), while wet grass can demand 60% more runway because water-slicked blades deny the tires their grip. This calculator applies the UK CAA's turf factors by surface state, so the after-rain fly-in gets planned on physics rather than nostalgia.
How to use Grass Strip Landing Distance Calculator
- 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula distance = paved figure × turf factor (dry 1.15 · long 1.35 · wet 1.6 · soft 1.25) substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Grass Strip Landing Distance Calculator?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula distance = paved figure × turf factor (dry 1.15 · long 1.35 · wet 1.6 · soft 1.25) with sources cited on the page
- ✓The paradox of turf: rolling resistance that fought your takeoff now helps you slow — but only until the grass is wet, when the blades become a lubricant layer and wheel braking quietly resigns. UK CAA factor for wet grass: up to 1.6.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
Why is wet grass so much worse than wet pavement?+
Wet pavement still offers texture through the film; wet grass interposes a continuous organic lubricant — flattened blades sliding on each other — between tire and soil. Friction can fall toward icy values while looking like a pleasant green carpet. The UK CAA's 1.6 landing factor for wet grass exceeds its wet-pavement guidance for exactly this reason.
Does soft ground shorten or lengthen a landing?+
It genuinely shortens the roll (wheels sinking absorb energy fast) — but the 1.25 factor here prices its real costs: ruts and hidden soft spots arrest unevenly, nose-over risk climbs for tailwheel and nosewheel alike, and braking inputs that worked on firm turf bury the nose. The distance is rarely the binding problem; the controllability is.
What's the right braking technique on grass?+
Less, later, smoother. Let aerodynamic drag and rolling resistance do the first half of the work (hold the yoke back; the drag-curve is your ally below flying speed), then test the brakes gently — turf grip varies metre to metre. Locked wheels on grass skid further than rolling ones decelerate, and skidding tears the strip the owner kindly lets you use.
How should I judge an unfamiliar farm strip's length and state?+
Walk it if at all possible: pace the length (a 1% optimistic length estimate is normal in landowner folklore), squeeze the soil for moisture, note the grass height against your boot, and find the soft spots a mower hides. Then run this tool's worst plausible surface class with your aircraft's figure plus the 1.43 landing safety factor — and decide on the ground, not on short final.
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