Take-off & landing distance

Take-off and landing distances start from a still-air, sea-level number in the POH, then you correct it for pressure altitude, temperature, and wind. The corrections compound: you multiply them, you never add them.

Real POH charts are graphs. This trainer uses one fixed, stated model so you can reproduce every step by hand:

• Pressure altitude: lengthens the roll. +10% per 1000 ft, factor 1 + 0.10 × PA/1000.
• Temperature: hot, thin air lengthens the roll. ISA at your altitude = 15 - 2 × PA/1000 °C; factor 1 + 0.01 × (OAT - ISA), so +1% per °C above ISA. Below ISA shortens it.
• Headwind: shortens the roll. -10% per 10 kt, i.e. factor 1 - 0.01 × kt.
• Tailwind: lengthens the roll, and hurts far more per knot. +10% per 2 kt, i.e. factor 1 + 0.05 × kt.
• Contaminated runway (landing only): a low CRFI (Canadian Runway Friction Index) means poor braking, so the landing distance grows. Read the multiplier from this trainer's CRFI table (illustrative model factors, not the published TC AIM CRFI table, which lists recommended landing distances), e.g. CRFI 0.40 compacted snow ×1.4, CRFI 0.20 ice ×2.2.

Multiply the book number by every factor that applies:

distance = base × PA-factor × temp-factor × wind-factor × CRFI-factor

The correction factors are unitless ratios, so they work in feet or metres. But mind the unit the book number is in: if the chart gives distance in feet and you want metres, convert (1 ft = 0.3048 m).

Pressure altitude and above-ISA temperature are the two halves of density altitude: hot and high both stretch the roll, so a hot day at a mountain strip stacks both penalties.

Trap: a tailwind costs about five times as much per knot as a headwind saves, so even a light tailwind lengthens the roll far more than the same headwind shortens it.

Source note: exact numbers and system details are aircraft-specific. These are typical light-trainer values; your own aircraft's POH/AFM is the authority.

Practice