Take-off distance calculator
Work out how much runway you need to take off today.
Take-off distance required
The flight manual figure times .
| Condition | Factor | Distance |
|---|---|---|
| Flight manual figure | 1.00 | |
The factors
From the UK's Safety Sense 09, Weight, Balance and Performance. They multiply together: dry grass at 2,000 ft is 1.20 × 1.20, not 1.40.
| Condition | Multiply by |
|---|---|
| Each 10% above the flight manual figure's weight | 1.20 |
| Each 1,000 ft of pressure altitude | 1.10 |
| Each 10°C above ISA | 1.10 |
| Dry grass, up to 20 cm, firm soil | 1.20 |
| Wet grass, up to 20 cm, firm soil | 1.30 |
| Soft ground or snow | 1.25 |
| Each 2% uphill slope | 1.10 |
| Tailwind of 10% of the lift-off speed | 1.20 |
| Safety factor, applied last | 1.33 |
Using the result
Use the flight manual's take-off distance to 50 ft. If its chart already allows for altitude and temperature, leave those blank here.
The answer has to fit in the runway's take-off distance available (TODA). If it doesn't, take less fuel or fewer people, wait for cooler air or a better wind, or use a longer runway.
Before you roll, pick a point on the runway, like the windsock or a holding point. If you're not going fast enough by then, stop.
Then check the other end of the trip with the landing distance calculator.
Straight answers
How do you calculate take-off distance required?
Take the take-off distance to 50 ft from the flight manual. Multiply it by a factor for everything worse than the manual assumes: weight, elevation, temperature, surface, slope and tailwind. Then multiply by 1.33. The answer has to fit in the take-off distance available.
What is the 1.33 take-off safety factor?
Room for the things the manual figure leaves out: an older engine and propeller, a less than perfect take-off, and a test pilot's numbers. The UK's Safety Sense 09 recommends it whenever the manual gives unfactored figures.
How much does grass add to the take-off run?
Dry grass up to 20 cm adds 20%, and wet grass 30%. Soft ground or snow adds at least another 25%. Longer grass and standing water add more, and can stop a take-off altogether.
Does a headwind reduce the distance required?
It shortens the run, but the calculator gives it no credit. If your manual has a wind correction, count only half the reported headwind, because the wind can drop during the run.
How do elevation and temperature affect take-off?
Thinner air means less power and less lift. Each 1,000 ft of pressure altitude adds 10%, and so does each 10°C warmer than standard.
Is the calculator free?
Yes. It is free for any pilot, club or school, with nothing to sign up for, and nothing you enter leaves your browser unless you save it to a flight plan.
More free tools
Every booking checked against your rules.
Volanti checks licence, medical, membership and recent hours when the booking is made.