Autopilot vs hand-flown...
None but a blockhead
Thread Starter
Join Date: Nov 1999
Location: London, UK
Posts: 535
Likes: 0
Received 0 Likes
on
0 Posts
Autopilot vs hand-flown...
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
Join Date: Aug 2004
Location: Leeds
Posts: 136
Likes: 0
Received 0 Likes
on
0 Posts
Pretty much as you said really.
There are times on our aircraft when autopilot cannot be used....below a 1000 feet not coupled to an ILS, with flaps at full, below 1000 feet after takeoff etc. As for hand flying, i would say most hand flying takes place in the cargo world as you dont have passengers to worry about when you are throwing it around compared to the auto pilot which is very smooth. Apart from on approach, i wouldnt say there is much hand flying at all in the pax world.
There are times on our aircraft when autopilot cannot be used....below a 1000 feet not coupled to an ILS, with flaps at full, below 1000 feet after takeoff etc. As for hand flying, i would say most hand flying takes place in the cargo world as you dont have passengers to worry about when you are throwing it around compared to the auto pilot which is very smooth. Apart from on approach, i wouldnt say there is much hand flying at all in the pax world.
Join Date: May 2007
Location: UK
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
People in the cargo world would love to hand fly some visual app's more but due to various reasons, dont often get the chance. I believe the charter guys are the ones who get the most hand flying...
Cheers,
SS
Cheers,
SS
Join Date: Aug 2002
Location: Europe
Posts: 141
Likes: 0
Received 0 Likes
on
0 Posts
It depends on the aircraft type being used. Old turboprops are almost always flown by hand in all flight regimes other than the cruise due to them having less sophisticated autopilots, assuming it's working in the first place that is! The same is true for some older jets. More modern aircraft will utilise automatics for a greater portion of the flight to reduce workload. Company SOPs also suggest how the automatics should be used but they will reflect the type being operated. There's no difference between cargo, charter, scheduled or Bizjets, it just depends on SOPs and aircraft type. 
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
At my company (aircraft type, L1011), there are no autopilot restrictions, except that it must be used for a CATII approach....no other altitude restrictions.
In fact, the autopilot can be engaged in control wheel steering (CWS) even for takeoff, quite handy during a complicated SID or noise abatement departure procedure, especially where low level turns are required.
And, of course, automatic approach/land (autoland) operations are a TriStar specialty....four channels of autopilot guideance, superb.
However, most pilots hand fly approaches, unless CATII.
In fact, the autopilot can be engaged in control wheel steering (CWS) even for takeoff, quite handy during a complicated SID or noise abatement departure procedure, especially where low level turns are required.
And, of course, automatic approach/land (autoland) operations are a TriStar specialty....four channels of autopilot guideance, superb.
However, most pilots hand fly approaches, unless CATII.
Join Date: Apr 2002
Location: Location: Location:
Age: 53
Posts: 1,110
Likes: 0
Received 0 Likes
on
0 Posts
I take personal pride in the fact that the boss cant tell whether the AP is engaged or not. The fact that he has a full cup of coffee 2 inches next to a very expensive biege headliner really focuses my mind somewhat.....
Join Date: Aug 2002
Location: Europe
Posts: 141
Likes: 0
Received 0 Likes
on
0 Posts
411A ....nice aeroplane, Lockheed do build great machines. Mine is the tristar's grandad, no CWS or 4 channel autopilot but none the less surprisingly advanced for it's day. G-SPOT......couldn't agree more, I'm not used to expensive headliner though 
Last edited by stellair; 1st Feb 2008 at 09:57.
Nemo Me Impune Lacessit
Join Date: Jun 2004
Location: Derbyshire, England.
Posts: 4,095
Received 0 Likes
on
0 Posts
Out of Heathrow my last company insisted that we take the AP at 400', (B747-400), climbing, in order to ensure we correctly tracked the SID and didn't incur noise violations. It is always nice to hand fly but that has to be balanced against overloading the PNF in busy terminal areas.
