Performance - take-off
Performance - take-off is the domain where the exam checks whether you can turn certified take-off data into a legal, obstacle-safe departure. It tests declared distances, speeds, limiting masses and the effects of density altitude, wind, slope, runway condition and thrust setting.
Declared distances and speeds
- TORA is the take-off run available; TODA adds clearway; ASDA adds stopway and is used for the accelerate-stop case.
- V1 is the decision speed, VR rotation and V2 the initial climb speed. V1 must not be below Vmcg and must allow the stop case within ASDA and the go case within TODA.
- The take-off distance required is the greater of accelerate-stop distance and distance to the AFM screen height; it must fit the declared distances.
Worked example
Assume the AFM chart gives a 2,400 m take-off distance required at 70,000 kg, sea level and ISA. A 1% uphill slope adds 5%: 2,400 × 1.05 = 2,520 m. With TODA 2,700 m, TORA 2,500 m and ASDA 2,600 m, the take-off run and accelerate-stop must also be checked. If they are 2,100 m and 2,350 m dry, the slope-adjusted values are 2,205 m and 2,468 m. All three fit, so TODA use is 93%, not TORA.
Traps
Do not compare the take-off distance required only with TORA. Do not apply wind as a percentage without the chart’s sign convention. A flex or derate take-off is invalid if the assumed thrust is unavailable or contamination changes the accelerate-stop case. Remember that V1 may be limited by Vmcg, brake energy or obstacle clearance.