5. Takeoff - General. The takeoff speeds described in paragraph (b), the accelerate-stop distance described in paragraph (c), and the takeoff distance described in paragraph (d), must be determined for -
(1) Each weight, altitude, and ambient temperature within the operational limits selected by the applicant;
(2) The selected configuration for takeoff;
(3) The center of gravity in the most unfavorable position;
(4) The operating engine within approved operating limitation; and
(5) Takeoff data based on smooth, dry, hard-surface runway.
(b) Takeoff speeds.
(1) The decision speed V1 is the calibrated airspeed on the ground at which, as a result of engine failure or other reasons, the pilot is assumed to have made a decision to continue or discontinue the takeoff. The speed V1 must be selected by the applicant but may not be less than -
(i) 1.10 Vs1;
(ii) 1.10 VMC;
(iii) A speed that permits acceleration to V1 and stop in accordance with paragraph (c) allowing credit for an overrun distance equal to that required to stop the airplane from a ground speed of 35 knots utilizing maximum braking; or
(iv) A speed at which the airplane can be rotated for takeoff and shown to be adequate to safely continue the takeoff, using normal piloting skill, when the critical engine is suddenly made inoperative.
(2) Other essential takeoff speeds necessary for safe operation of the airplane must be determined and shown in the Airplane Flight Manual.
(c) Accelerate-stop distance.
(1) The accelerate-stop distance is the sum of the distances necessary to -
(i) Accelerate the airplane from a standing start to V1; and
(ii) Decelerate the airplane from V1 to a speed not greater than 35 knots, assuming that in the case of engine failure, failure of the critical engine is recognized by the pilot at the speed V1. The landing gear must remain in the extended position and maximum braking may be utilized during deceleration.
(2) Means other than wheel brakes may be used to determine the accelerate-stop distance if that means is available with the critical engine inoperative and -
(i) Is safe and reliable;
(ii) Is used so that consistent results can be expected under normal operating conditions; and
(iii) Is such that exceptional skill is not required to control the airplane.
(d) All engines operating takeoff distance. The all engine operating takeoff distance is the horizontal distance required to takeoff and climb to a height of 50 feet above the takeoff surface according to procedures in FAR 23.51(a).
(e) One-engine-inoperative takeoff. The maximum weight must be determined for each altitude and temperature within the operational limits established for the airplane, at which the airplane has takeoff capability after failure of the critical engine at or above V1 determined in accordance with paragraph (b) of this section. This capability may be established -
(1) By demonstrating a measurably positive rate of climb with the airplane in the takeoff configuration, landing gear extended; or
(2) By demonstrating the capability of maintaining flight after engine failure utilizing procedures prescribed by the applicant.