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Complete Landing Distance Calculator (All Factors)

The full landing chain in one pass: density altitude, wind, speed discipline, surface, slope and the 1.43 safety factor — your real number against the real runway.

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Factored distance required (ft)
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Runway to spare (ft)
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Total multiplier on book

Note which factor is yours: altitude, wind, surface and slope belong to the day, but (V/Vref)² belongs to you. The chain quantifies how speed discipline is the one correction that costs nothing and pays everywhere.

Formula

book × 1/σ × (V/Vref)² × wind × surface × (1+0.1·slope) × 1.43 ≤ LDA
References: UK CAA Safety Sense Leaflet 7: Aeroplane Performance; FAA AC 91-79B; Anderson, Aircraft Performance and Design, §6.3 (takeoff/landing ground roll)

⚠️ 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.

The full landing chain in one pass: density altitude, wind, speed discipline, surface, slope and the 1.43 safety factor — your real number against the real runway.

About Complete Landing Distance Calculator (All Factors)

Landing assessments fail in the gaps between single-factor rules, so this calculator closes the chain: book figure, density altitude, your honest approach speed (not the placard one), wind component, surface state, slope, then the CAA's 1.43 landing factor — finally compared against the actual LDA. The total multiplier it reports regularly lands between 1.8 and 2.5 for ordinary summer days at modest strips, which is precisely why 'the book says 1,335 ft' and 'the strip is 1,800 ft' can both be true while the landing is not.

How to use Complete Landing Distance Calculator (All Factors)

  1. 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
  2. 2Read the live results: .
  3. 3Check the "With your numbers" line to see the formula book × 1/σ × (V/Vref)² × wind × surface × (1+0.1·slope) × 1.43 ≤ LDA substituted step by step.
  4. 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.

Why use Complete Landing Distance Calculator (All Factors)?

  • Instant, free and private — every calculation runs in your browser, nothing is uploaded
  • Built on the published formula book × 1/σ × (V/Vref)² × wind × surface × (1+0.1·slope) × 1.43 ≤ LDA with sources cited on the page
  • Note which factor is yours: altitude, wind, surface and slope belong to the day, but (V/Vref)² belongs to you. The chain quantifies how speed discipline is the one correction that costs nothing and pays everywhere.
  • Switch units, tweak any input and watch every result update live

Frequently asked questions

Why does the landing chain use 1.43 instead of takeoff's 1.33?+

The UK CAA's classic guidance pairs 1.33 for takeoff with 1.43 for landing — landings carry more outcome variance: flare judgment, touchdown-point scatter, the speed you actually crossed the fence with versus intended, and brake/surface condition discovered only on rollout. The bigger factor mirrors the bigger spread between demonstration and dailies.

Which input do most pilots enter dishonestly?+

The flown speed. Everyone types Vref; flight-data studies of GA approaches show habitual +5 to +10 kt over the fence. Enter the speed your last three landings actually crossed at (a CFI ride or GPS log will tell you), and let the (V/Vref)² term reveal what that habit costs. The tool can't fix the habit, but it refuses to hide its price.

How do the factors interact — can good news offset bad?+

Multiplicatively, in both directions: a 9-kt headwind (×0.9) genuinely offsets short dry grass (×1.15) almost exactly. The trap is spending credits twice — counting headwind here and mentally adding 'plus the wind will help.' Enter every condition once, let the chain do the netting, and treat the final number as spent the moment you read it.

The verdict says 'fits raw, fails factored' — can I go anyway?+

Legally (Part 91), often yes; that's exactly what the amber verdict says aloud. The question to answer first: which specific line of the chain are you planning to beat the book on — and what's your evidence? If the honest answer is 'none, I'll just be careful,' the margin you're spending is the one that exists because careful pilots still get scatter. Wait for wind, burn fuel down, or use the longer runway.

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