Self Loading Freight
23rd Jan 2008, 01:05
When do pilots fly aircraft by hand, and when do they use the autopilot?
This question came up in conversation recently, and I could only guess at the answer... and being a spod who likes to know rather than guess, I thought I'd ask here.
My best guess:
Takeoffs are always, always hand-flown.
Normally, the autopilot is engaged very shortly after take-off, to let the flight crew get on with configuring the aircraft for the cruise.
In a normal flight with no nasty weather or unexpected manoeuvers, the autopilot is left on, with unplanned level changes and rerouting managed by reprogramming the flight computer, until well into the approach.
Landings are usually hand-flown, unless the visibility makes it safer to let the computer do it and the airfield/aircraft are suitably equipped (I know there are various categories, I don't know what the numbers mean).
I qualified those guesses by further guesses, that pilots who feel that they need practice hand-flying, who have a sim check coming up or who actually enjoy it, will indulge in the practice more often than normal, but that on interminable stretches during long-haul when there's nothing to do but keep the nose pointing in the right direction, there's not much point. If you're in trim, there's nothing needing doing, right? And stuff like keeping the attitude correct as the fuel levels/CoG change is going to be far better left to the machinery.
Also, that there are plenty of weather conditions where the control laws the autopilot follows aren't optimal (the bouncy bits) so it's better having an adaptable human doing that bit of the feedback loop. I didn't know about holding, but from my experiences of timing the loops (you've got to do something to take your mind off the notion that all four engines have been enthusiastically emptying the tanks for twelve hours already), that feels automatic. It's normally to the second, anyway.
Was I close? Also, is 'autopilot' the right term, or is it better to talk about the various levels of automation that I imagine a flight computer can perform?
Spottishly,
R
This question came up in conversation recently, and I could only guess at the answer... and being a spod who likes to know rather than guess, I thought I'd ask here.
My best guess:
Takeoffs are always, always hand-flown.
Normally, the autopilot is engaged very shortly after take-off, to let the flight crew get on with configuring the aircraft for the cruise.
In a normal flight with no nasty weather or unexpected manoeuvers, the autopilot is left on, with unplanned level changes and rerouting managed by reprogramming the flight computer, until well into the approach.
Landings are usually hand-flown, unless the visibility makes it safer to let the computer do it and the airfield/aircraft are suitably equipped (I know there are various categories, I don't know what the numbers mean).
I qualified those guesses by further guesses, that pilots who feel that they need practice hand-flying, who have a sim check coming up or who actually enjoy it, will indulge in the practice more often than normal, but that on interminable stretches during long-haul when there's nothing to do but keep the nose pointing in the right direction, there's not much point. If you're in trim, there's nothing needing doing, right? And stuff like keeping the attitude correct as the fuel levels/CoG change is going to be far better left to the machinery.
Also, that there are plenty of weather conditions where the control laws the autopilot follows aren't optimal (the bouncy bits) so it's better having an adaptable human doing that bit of the feedback loop. I didn't know about holding, but from my experiences of timing the loops (you've got to do something to take your mind off the notion that all four engines have been enthusiastically emptying the tanks for twelve hours already), that feels automatic. It's normally to the second, anyway.
Was I close? Also, is 'autopilot' the right term, or is it better to talk about the various levels of automation that I imagine a flight computer can perform?
Spottishly,
R