Control column flailing during the flare - a dangerous practice by some pilots.
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Well, I used to move the yoke (not that much the control column though) on 747 the same way in gusty conditions. I was not reacting on the bank change, but rather on the tendency of the change, barely visible. It prevents the aircraft from developing more bank. If you react later your wll be more visibly banking. And yes, on the conventionaly controlled aircraft you have to immediately move the yoke in the opposite direction to stop it from going into deeper bank.
It’s more comlicated then the way you are discussing it here.
On FBW aircraft it’s whole different story.
It’s more comlicated then the way you are discussing it here.
On FBW aircraft it’s whole different story.
I haven’t been able to find a common factor yet, although many have come off the FBW Airbus...
A lot of this stems from poor training. I frequently hear pilots talk in terms of using the controls to move the nose up or down, or to roll - whereas what they should be doing is using the controls to select an attitude. It's basic stuff, but with current training systems such as the MPL where pilots can be at the controls of a large jet with less than 100 hours flying experience, the basics are either quickly forgotten as a result having not enough time to consolidate skills, or just not being taught correctly in the first place. We are creating aircraft drivers, not pilots.
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On Airbus FBW types, I often see the stick stirring commencing as soon as the AP is disconnected regardless of what the air around the aircraft is doing.
I've seen this done by pilots that were certainly not nervous. I wondered why they did it, and figured it came about from poor technique learned early in their flying career. They made an easy landing look very hard.
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Does the technique matter if it’s safe and if it produces the results? like criticising someone’s golf swing!
I had a PhD student a few years ago looking at piloting technique in the simulator - he noticed that when flying a precision tracking task, if he plotted stick position against time - the pilots with the largest range and rapidity of movement both usually had the last hours, and the lowest ability to handle handling related emergencies (we were throwing loads through the sim at the time as part of a research project).
That said, I used to fly with an F/A-18 pilot from the USN who did this all the bloody time in a Hawk - and with the throttle as well. It seemed to make him happy, but the aeroplane responses were far slower than his inputs, so it made no difference whatsoever. He thought it was something to do with habits picked up on carrier landings!
Testing and teaching on light aeroplanes on the other hand - it can be positively problematic in ground effect as it makes it far too easy to enter a PIO.
G
That said, I used to fly with an F/A-18 pilot from the USN who did this all the bloody time in a Hawk - and with the throttle as well. It seemed to make him happy, but the aeroplane responses were far slower than his inputs, so it made no difference whatsoever. He thought it was something to do with habits picked up on carrier landings!
Testing and teaching on light aeroplanes on the other hand - it can be positively problematic in ground effect as it makes it far too easy to enter a PIO.
G
There is an interesting comment on the subject of high gain and low gain pilots by John Farley in his book "A View From the Hover."
"Over-control is a common problem with learning to fly, almost regardless of the task but with experience we get better at relaxing, better at trimming, better at letting it fly itself for a bit and then coaxing it back to the desired state. In fact better at becoming a low gain (relaxed) pilot rather than being a high gain (overactive) one. Airplanes take time to respond and it is a waste of time to oscillate controls.”
I am not going to argue with such an eminent personage and it's the way I have always tried to do it.
"Over-control is a common problem with learning to fly, almost regardless of the task but with experience we get better at relaxing, better at trimming, better at letting it fly itself for a bit and then coaxing it back to the desired state. In fact better at becoming a low gain (relaxed) pilot rather than being a high gain (overactive) one. Airplanes take time to respond and it is a waste of time to oscillate controls.”
I am not going to argue with such an eminent personage and it's the way I have always tried to do it.
A few years ago I went to Dublin to get revalidated on the B737. The TRE tried to tell me that at the flare, both hands would be required on the yoke. What for? says I. Because it is so heavy and you will have more precise control says he. Bull**** says I , and who will select reverse? The FO does that says he. Not on my watch says I, unless he did the landing.
It was an interesting insight into some fckud up training inspired presumably from watching too many B grade WW II movies.
But I did note that wearing white gloves seemed to make it work for him.
It was an interesting insight into some fckud up training inspired presumably from watching too many B grade WW II movies.
But I did note that wearing white gloves seemed to make it work for him.
Very close formation flying aside, we should try and do as the auto pilot does. To me the autopilot is the smoothest guy/gal in town. Now they're real smooth. In case you haven't noticed, on a non FBW aircraft, the control column will hardly move most of the time, when the A/P is strutting it's stuff. I have seen pilots manipulate the controls almost as smooth as the A/P but not quite.Some people will never be smooth. some people are "natural" pilots some aren't. However in airline operations, piloting skills/smoothness appear to be well down the list priorities. Apart from extra fuel burn, passenger discomfort. lack of finesse and wearing yourself out, not many people seem to care. The smoothest I've witnessed in my long career was an Ex WW2 mosquito pathfinder pilot. You either have it or you haven't. Period. Would loved to have flown with Bob Hoover for eg. he was of course good to see outside the cockpit but my money is on he would have been equally impressive inside the cockpit also.<br /><br />IMHO, of course.
Last edited by Dan_Brown; 20th Aug 2018 at 22:07.
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I have noticed this tendency for some pilots to be very active on the controls - particularly during final approach and through flare. I am very curious what others who have noted this would have to say regarding the frequency range for such inputs. Particularly at low speeds (such as approach), transport category aircraft have response bandwidths that are half a Hz or less. Inputs at frequencies higher than this (less than two seconds per cycle) will have little impact on the airplane's attitudes (pitch or roll) and even less impact on flight path. One theory I have for this is that some pilots feel that they want greater bandwidth out of the airplane response and thus tend to drive the controls aggressively at higher frequencies thinking it will help.
A few entries back a question was posed as to whether or not this stirring the mayo actually causes the surfaces to move. The answer is yes. Transport category airplane control systems that I am familiar with have surface rate capabilities on the order of 50 degrees or more per second. For a control surface that has a stop to stop travel range on the order of 50 degrees, sawing the pilot controls back and forth half travel at 1 Hz will drive the corresponding surface(s) at their rate limits through a range of 25 or more degrees.
Abrupt inputs at higher frequencies will tend to stir up flexible structural modes. For larger transports the associated modal natural frequencies can be as slow as 2 Hz or less. Feeding energy into body flex modes does nothing toward controlling airplane attitude or path, but sure degrades the ride quality. One name for this is pilot induced turbulence as mentioned earlier in this thread! I wonder if pilots with experience on larger airplanes that tend to exhibit more flex effects have learned to resist being aggressive on the controls because of the negative impact of driving the flex modes while pilots on smaller airplanes don't get as much feedback from the seat of the pants that high frequency inputs are not a good idea.
FBW airplanes with stability augmentation control systems use both pilot controller inputs and stability enhancing feedback signals to command the control surfaces. If the pilot is really stirring the pot with large, higher frequency inputs the result can be that the surfaces spend most of their time sawing back and forth at their rate limits. When the surfaces are rate limited due to pilot input they are not able to simultaneously respond to stability augmentation feedback commands. The augmentation is essentially lost - not a good situation for a relaxed stability configuration.
A few entries back a question was posed as to whether or not this stirring the mayo actually causes the surfaces to move. The answer is yes. Transport category airplane control systems that I am familiar with have surface rate capabilities on the order of 50 degrees or more per second. For a control surface that has a stop to stop travel range on the order of 50 degrees, sawing the pilot controls back and forth half travel at 1 Hz will drive the corresponding surface(s) at their rate limits through a range of 25 or more degrees.
Abrupt inputs at higher frequencies will tend to stir up flexible structural modes. For larger transports the associated modal natural frequencies can be as slow as 2 Hz or less. Feeding energy into body flex modes does nothing toward controlling airplane attitude or path, but sure degrades the ride quality. One name for this is pilot induced turbulence as mentioned earlier in this thread! I wonder if pilots with experience on larger airplanes that tend to exhibit more flex effects have learned to resist being aggressive on the controls because of the negative impact of driving the flex modes while pilots on smaller airplanes don't get as much feedback from the seat of the pants that high frequency inputs are not a good idea.
FBW airplanes with stability augmentation control systems use both pilot controller inputs and stability enhancing feedback signals to command the control surfaces. If the pilot is really stirring the pot with large, higher frequency inputs the result can be that the surfaces spend most of their time sawing back and forth at their rate limits. When the surfaces are rate limited due to pilot input they are not able to simultaneously respond to stability augmentation feedback commands. The augmentation is essentially lost - not a good situation for a relaxed stability configuration.
ancient memory
Vilas said
I remember one particular day in late 1964 watching aircraft landing on a very gusty day at Heathrow, and noticing that the 707s were rocking quite a bit but the VC10s not at all. Anybody remember the VC10 being easier to control, or was I imagining it?
B707 during base flying it was very evident who is giving unnecessary input because it used to react late with lateral rocking while it was possible to fly it rock steady with proper handling.
but the VC10s not at all. Anybody remember the VC10 being easier to control, or was I imagining it?
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To me, that kind of control flogging screams, "I'm so afraid the aircraft is going to get away from me, I have to stay on top of it". It's fear.
I'd doubt the airmen can ever admit that to themselves.
I'd doubt the airmen can ever admit that to themselves.