Takeoffs

Takeoff distance increases: 

—with increased altitude and temperature

—with greater weight (A 10% increase in weight may increase the takeoff distance by 25%)

—with a tailwind (An airplane taking off in a 20-knot headwind is already 20-knots closer to the liftoff indicated airspeed / Tailwinds in excess of 5 knots are normally not considered suitable for takeoff). Tailwinds lengthen the ground run and flatten the climb-out

—with an upslope runway (A 2% upslope may increase takeoff distance to 50 ft by approximately 50%. Upslope provides a retarding force that impedes acceleration because the engine has to overcome gravity as well as surface friction and drag, resulting in a longer ground run or takeoff.)

—with soft ground or long grass (especially if wet). These will reduce acceleration and can increase takeoff distance by as much as 25%. Gravel has the same effect as short dry grass. Pools of water can significantly retard acceleration, and takeoff under these circumstances warrants careful consideration. Soft, wet ground or a soft, sandy surface might make acceleration to liftoff speed impossible no matter what runway length is available.

• Flaps will reduce the ground run, but may not reduce the takeoff distance to clear a 50 ft obstacle. This is because increased drag reduces excess thrust and thereby the angle of climb.

•A wind will not affect the time, fuel, and air distance to reach the required altitude, but it will affect the ground distance covered.

•Reducing weight by 200-300 lbs can reduce take-off distance by as much as 1000 ft.

•Aircraft will usually underperform the calculated takeoff distance in the POH because of older engines, etc. (Add a 20% safety margin like the airlines do)