Take-Off Distance

Three take-off tables are printed, one for each of three weights, and every figure in them is a grass-runway figure at full throttle. Two things must be done to a raw table value before you can use it: apply the corrections for wind, surface and slope, and then apply the in-service factor.

At a glance

• In-service factor, applied to distances1.10
• Conditionsrunway GRASS · flaps T/O · throttle full forward · lift-off 50 KIAS · 61 KIAS over the 50 ft obstacle
• Runway slopeground roll +7% per +1% of slope
• Paved runwayground roll −10%
• Headwind−5 m per kt (16 ft/kt)
• Tailwind+15 m per kt (49 ft/kt)
• 650 kg, sea level — ground roll (at −25 / 0 / 25 / 50 °C, then ISA)149 / 187 / 231 / 280 m, ISA 213 m
• 650 kg, sea level — to 50 ft AGL262 / 328 / 401 / 484 m, ISA 371 m
• 650 kg, 5000 ft — ground roll231 / 291 / 359 / 436 m, ISA 304 m
• 650 kg, 5000 ft — to 50 ft AGL402 / 502 / 614 / 740 m, ISA 524 m
• 650 kg, 10000 ft — ground roll365 / 460 / 567 / 688 m, ISA 441 m
• 650 kg, 10000 ft — to 50 ft AGL624 / 780 / 956 / 1152 m, ISA 748 m
• 600 kg, sea level — ground roll123 / 155 / 191 / 231 m, ISA 176 m
• 600 kg, sea level — to 50 ft AGL218 / 272 / 333 / 402 m, ISA 308 m
• 550 kg, sea level — ground roll100 / 125 / 155 / 188 m, ISA 143 m
• 550 kg, sea level — to 50 ft AGL178 / 223 / 273 / 329 m, ISA 252 m

What the tables assume

A grass runway, flaps at T/O, full forward throttle, lifting off at 50 KIAS and crossing the 50 ft obstacle at 61 KIAS. Grass is the baseline here rather than the exception, which is why the paved-runway correction takes distance off instead of adding it.

NOTE — Multiply distances by 1.10 to account for the performance variations likely in service.

Corrections

• Runway slope — for every +1% of slope, add 7% to the ground roll.

• Paved runway — take 10% off the ground roll.

• Headwind — subtract 5 m per kt, or 16 ft/kt.

• Tailwind — add 15 m per kt, or 49 ft/kt.

Wind is not symmetric. A knot of tailwind costs three times what a knot of headwind saves, which is the single most useful thing on this page.

At 650 kg

• Sea level — ground roll 149 / 187 / 231 / 280 m at −25 / 0 / 25 / 50 °C, then ISA 213 m; to clear 50 ft AGL 262 / 328 / 401 / 484 m, ISA 371 m.

• 5000 ft — ground roll 231 / 291 / 359 / 436 m, ISA 304 m; to clear 50 ft AGL 402 / 502 / 614 / 740 m, ISA 524 m.

• 10000 ft — ground roll 365 / 460 / 567 / 688 m, ISA 441 m; to clear 50 ft AGL 624 / 780 / 956 / 1152 m, ISA 748 m.

At lower weights

• 600 kg, sea level — ground roll 123 / 155 / 191 / 231 m, ISA 176 m; to clear 50 ft AGL 218 / 272 / 333 / 402 m, ISA 308 m.

• 550 kg, sea level — ground roll 100 / 125 / 155 / 188 m, ISA 143 m; to clear 50 ft AGL 178 / 223 / 273 / 329 m, ISA 252 m.

Check yourself

• What factor is applied to take-off distances, and why?

• What surface do the tables assume, and what correction applies on a paved runway?

• Compare the headwind and tailwind corrections. Which costs more per knot, and by how much?

• What is the 650 kg sea-level ground roll in ISA conditions?

• What speed is assumed over the 50 ft obstacle?

Study aid — always fly your aircraft's current AFM/POH.