CS 25.109 Accelerate-stop distance
(a) The accelerate-stop distance on a dry runway is the greater of the following distances:

(1) The sum of the distances necessary to –

(i) Accelerate the aeroplane from a standing start with all engines operating to V_EF for take-off from a dry runway;
(ii) Allow the aeroplane to accelerate from V_EF to the highest speed reached during the rejected take-off, assuming the critical engine fails at V_EF and the pilot takes the first action to reject the take-off at the V₁ for take-off from a dry runway; and
(iii) Come to a full stop on a dry runway from the speed reached as prescribed in sub-paragraph (a)(1)(ii) of this paragraph; plus
(iv) A distance equivalent to 2 seconds at the V₁ for take-off from a dry runway.

(2) The sum of the distances necessary to –

(i) Accelerate the aeroplane from a standing start with all engines operating to the highest speed reached during the rejected take-off, assuming the pilot takes the first action to reject the take-off at the V₁ for take-off from a dry runway; and
(ii) With all engines still operating, come to a full stop on a dry runway from the speed reached as prescribed in subparagraph (a)(2)(i) of this paragraph; plus
(iii) A distance equivalent to 2 seconds at the V₁ for take-off from a dry runway.