Excellent point Compressor Stall. If the acceleration is below the charted rate due to a number of reasons you will end up further down the runway at V1 and therefore a rejected take-off may well result in a runway over run if it is conducted near V1. Dragging brakes, reverted rubber aqua planning and reduced power etc., are all risks. Slightly less obvious is a rise or hump in the runway. Rwy11/29 at Darwin is a good example. ERSA lists it as level since the elevation of both thresholds is the same. You can imagine what happens in a heavy commercial aircraft. The initial acceleration will clearly be slower since it is uphill with V1 reached further down the runway. Any abort will be down hill. None of this is considered in basic performance calculations. I’m not sure how the latest computer calculated take-off data goes with this such as the Boeing Lap Top Tool and others. One advantage of MilSpec 3011 and 5011 is that an acceleration check time is utilised to a speed somewhat below V1. If you don’t make the speed within the time (with a bit of a buffer) you are still well short of V1 and can safely abort. This strategy would have saved the Emirates A340 in Melbourne from tail striking on take-off after a much lower takeoff weight was put into the FMS.
Beez