Well .. even if their calculations (EFB?) indicated maximum thrust reduction with maximum use of the ASDA, there is a bit of margin built into the procedures (though not advertised!), a.o.:
- Reverse Thrust: (FAR/CS 25.109) from a dry RWY no reverse thrust is taken into account (idle forward thrust), so any reverse thrust would have decreased the ASDR;
- Reaction times: (FAR/CS 25.109) depending on certification limits used (amdt 25-42/92), the certified reaction times [1-2 secs recognition/accel time, brake (1 sec), spoilers (1 sec) - dry] provide a bit of margin;
- Conservatism when using a reduced thrust takeoff: actual thrust will be higher than the rated thrust at the assumed temperature, because the actual air density is higher; actual true airspeed will be lower, because the actual ambient temperature is lower; lower true airspeed combined with the higher thrust will result in a shorter ground distance
So, if you want to perform a post-V1 abort (once again:
), you still stand (a bit of) a chance when departing from a dry runway
... much more than from a wet
or contaminated
runway!