Hi John
Pitch In take off follow SOPs (in A320 15š at an approximately 3š/sec rate, then FD).
It could be stated that flying consists on maintaining a sequence of
states of equilibrium. Maintain-change-maintain-change-maintain... all the time. The transition between each two different states is a
manoeuver. The transition can occur in many different ways to the same final outcome.
For instance you are descending at 280 kt and 2500 fpm V/S with a given pitch (
V/S mode) and thrust (
SPEED mode). You ask for "V/S minus 1000" to the PNF. Then the bar goes up. If you lag a couple of seconds, you don't have to rush behind the bar! You are just going to start "late", but there is no hurry. It is not an evasive manoeuvre. You decided yourselve to reduce rate to -1000. It was not the command of God. You will achieve the -1000 when it suits you. No reason to haste. Donīt let the computer push you. Smoothly pitch up. When the rate reaches -1000 fpm, you will have reached the new state of equilibrium. The bar will be in place because you have 1000 fpm. If it moves silightly, the computer has detected a departing trend. Follow it. The computer senses and calculates faster than you. Maintaining a state of equilibrium is not a manoeuver, it is just avoiding to depart from that state with minute inputs.
Instead, you could have pitched up aggresively. The same pitch amount carried out in less time (higher pitch rate) means a higher AoA and therefore a more abrupt and irregular flight path change. Performance will react accordingly. Maybe the computes will determine that it is time to pitch down a bit, now, so you find yourselve pitching down so as to not go below the -1000 fpm performance target.
I would say that, as a rule, a good manoeuvre is such that you transition progresively from the original to the final state as if you were passing through infinite mid states. Like a "quasistatic" change. It is much better for those pilots who still have to trim, specially.
FD "gains" and algorithms are designed in a given way. I don't know which way
. But in a specific way. If you follow the bar in the way you are expected to follow it by the designers, then it will work very well!
But who knows that way?
In Roll: Same applies to rolling into a turn. The bar moves instantly. If the change of heading will be large, the FD will command maximum bank. You roll smoothly to that bank. You will know what the commanded bank is because the bar is in place.
In the case capturing a heading or a track or a course: the FD bar has some mathematical algorithms that depend on the bank angle, the heading rate of change, the altitude and others to determine when to start rolling out of the turn. The more you lag after the FD bar moves, the more agressive you will have to be to avoid overshooting. I deem that after the FD bar moves you still have a second or so to start a smooth roll rate out of the turn without overshooting.
My advise:
Follow the bars or turn the FD off,
but don't haste in doing so. Fly as smoothly as you would if you were flying FDs OFF. Once you have the bars in place, don't let them go. They are there to help you maintain the demanded performance without you having to use too much brain resources. The FD is a wonderful tool, specially in approach.
With practice you can fly it perfectly (and not be flown by it). Practice means not only that you have to fly AP OFF regularly... But also with FDs OFF, if they let you. And even without A/THR, if your airline or captain are not scared of that
. Only then you will really master flying with the FD.
Hope it helps