Originally Posted by
Jwscud
Tourist - regarding your idea of a dynamic V1, I agree it is technologically possible. The main question any good analysis would ask is is it worth it? Perf A does not exactly provide massive margins at the moment (look at wet takeoff performance on a limiting runway for example) so I fundamentally don't see there is much more than an extra few hundred kilos of payload to get out of it.
Had a bit more of a think about advantages of dynamic V1.
All the current performance figures including V1 are based upon worst acceptable pilot having longest acceptable reaction time, worst acceptable engines etc etc.
A possibly very large advantage (depending on age of engines) of dynamic V1 is that the
actual acceleration rate and
actual engine thrust on the day would be used rather than worst possible case.
All the little safety factors added to temperatures, thrusts, could be quite reasonably removed as well as the human failing related fudge factors.
It would also allow go no-go decisions in real time utilising information about whether full thrust reverse would be available which could make an enormous difference to the critical point.
i.e. If the reason for the alert is cabin fire rather than engine failure, it is reasonable to assume that thrust reverse will work, therefore it could safely make the decision to stop thus avoiding taking a fire airborne at a much higher speed.
If however the problem is an engine failure, it is no longer reasonable to expect full reverse to be effective, so the aircraft may have already passed the critical point.
I suppose another side bonus would be that the accel data would flag up any weight finger trouble issues as well.
If the briefed mass and known thrust don't meet the expected acceleration figures, the aircraft will know it very early.
No more incorrectly set reduced thrust take-offs.
If the aircraft was not performing as expected, the aircraft would know it pretty much instantly and either add power or abort nice and early without causing an incident.
Edited to add This last could obviously be added to current aircraft without difficulty! Why isn't it?