Every choice of V1 buys one case at the other's expense: decide late and the stop grows, decide early and the crippled continuation grows. This lesson lives inside that trade. It works through the accelerate-stop distance and everything that moves it, meets the rejected take-off's real hazards, and then draws the most examined diagram in the subject: take-off distance falling against V1, accelerate-stop rising, and the balanced field where they cross.
The accelerate-stop distance in detail
The ASD responds to the whole cast from the previous lesson, in the stop's own directions: mass, altitude and temperature stretch it; a tailwind or a downslope stretches it doubly, feeding the acceleration and starving the braking; and it is evaluated for the engine-failure case and the all-engines case alike, the worse governing. Its anatomy is fixed: accelerate to V1 (losing the engine at VEF in the failure case), continue for 2 seconds at V1, then decelerate with the certified means. On a dry runway those means are maximum wheel braking and the ground spoilers: the spoilers dump the lift so the brakes have weight to work on, and reverse thrust earns no credit on a dry runway, counting only on wet and contaminated ones. A higher-than-scheduled V1 stretches the ASD sharply, the energy to be destroyed growing with the square of the speed.
The stopping machinery has its own physics. Anti-skid holds each wheel at the edge of the friction peak, and its failure removes so much braking that the dispatch tables charge a heavy distance penalty. The brakes themselves are energy sinks with a certified ceiling (the VMBE story from the previous lesson), and their temperature keeps rising for minutes after the stop: the delayed peak is why a rejected take-off is followed by cooling schedules and why fuse plugs exist to deflate an overheated tyre before it bursts. Brake-temperature indications, where fitted, are read before the next departure, not only after the last.
The high-speed rejected take-off is the manoeuvre these numbers guard, and its hazards are pure BK: from near V1 at high mass, the overrun risk, brake fires and tyre failures make the stop genuinely dangerous, which is why crews are trained go-minded in the last knots before V1: past the decision speed, continuing on one engine is almost always the safer act than stopping from beyond it.