Originally Posted by Super VC-10
Anyone done the maths?
The data probably aren't there for us to answer the question how long it takes to stop an A320 at 62.7 tons from 70 kts with one engine on reverse thrust and the other at 1.2 EPR with a moderate dry-runway coefficient of friction. AI probably has the models, and I would guess someone with access to good models and a supercomputer may well try to do so in order to see how much the runway surface condition may have contributed to the overrun.
However, it is easy to say what acceleration they would have to have achieved in order to stop from a 70-kt touchdown. Acceleration of -1.5 m/s/s gives a stopping distance of about 1634 m, and acceleration of -1.4 m/s/s gives a stopping distance of 1750 m.
So if you have them planning manual braking, getting WoW at 1650 m remaining and taking a second to react with manual brakes, then they would have needed to achieve about 20% more deceleration than they actually did achieve with manual braking in order to stop within the asphalt.
I don't know whether that will turn out to have been possible, but from what we know at this point I consider it plausible that that could have been achieved on a dry runway.
PBL