Boeing/Airbus low speed performance ?? (and no this is not a Boeing vs Airbus thread)

[747FOCAL]

I have a question for you pilots that have flown both Boeing and Airbus aircraft. The question is on low speed performance and the differences, not which performs better.

With Airbus being a more computer controlled aircraft than most Boeings does this affect the ability of the pilot to make decisions on how the takeoff profile will be flown? Primarily my question deals with takeoff speeds.

I know you guys calculate the required speeds based on various criteria. But on Boeings I have been told you end up using Vmin speeds where on Airbus the computer chooses the speeds and tells you what you will be flying.

Does a Boeing aircraft allow you to derate the takeoff more?

On every Airbus aircraft I have flown on sensing the cutback was very easy, yet on a Boeing it is nearly impossible, even at very noise sensative airports. Since cutback is manual on a Boeing and automatic on an Airbus, do you even bother on the Boeing?

So I guess the short of my question is, do you have less control of how your climb out is going to occur flying an Airbus vs a Boeing?

Thanks to all in advance for your time. :ok:

[Lemurian]

747FOCAL,Hi!
There appears to be some misunderstanding of the 'Bus,here.
You are right on the speed computation,there are quite a lot of SOP's on this subject.Basically,an airline decides on its own performance manual,hence the take-off speeds,based on the airport particulars,the choice of a V1,the V2/Vr ratio....etc...the weather conditions and of course the airplane take-off mass.
On the 'Bus,these speeds are entered on the Take-off perf page and the V2 you have typed in is the basis of your flight path...it determines what we call SRS (speed reference) as V2+10 will be the target of your climb-out ,materialised by the pitch command of your Flight Director.
On the same Take-off perf page,you enter three altitudes:
THR reduction altitude
Acceleration
Engine-out acceleration.
On a normal take-off,the passage of the cutback at " THR RED" is announced by a "LVR CLB"flashing message on your FMA.You then just pull the lever two clicks to the CLB detent,the SRS being still valid,until you reach the accel altitude,at which the FMGS take control of your speed computations,the target moves to 250 kts and the flap retraction speeds appear.You then clean up your airplane on that schedule.
Basically,on a Boeing,the procedure is the same but you'd need to manually set your thrust levers (Don't know about the 777,though...)
Did I make sense?

[747FOCAL]

Lemurian,

Thanks and yes that does clear up some stuff, but I still wonder if the Airbus is using an enhanced speed/procedure where as Boeings are not??? :confused:

[Lemurian]

747FOCAL,
On normal operations,I would say no,as the choice of the climb out speeds is in fact left to the operator.On another thread dealing with Boeing 737 climb and clean-up speeds,you have a partial answer.

One has also to consider that modern jets are very rarely limited in their 2nd segment or obstacle performance.

If you have an engine failure,it becomes an altogether different kettle of fish,the 'Bus will provide you with the best available computed performance BUT not on your initial climb,where you will be using the V2 you have chosen.
After you have retracted your flaps,selected the Max Continuous Thrust detent of the thrust levers,you will be aiming to climb out at "Green Dot"(roughly min drag speed Vmd),which is provided by the FMGS,based on the aircraft actual weight...etc...