Provided an aircraft with a fly-by-wire system, there are basically two possible choices when it comes deciding how to let the pilots interface with it:

  • rate control / attitude hold: a deflection of the stick will command a certain rate, releasing it will make the system maintain the current attitude. See the Airbus Normal control law.
  • direct control: a deflection of the yoke will directly translate to a deflection of the surfaces, mimicking the "old" mechanical control setup. It is my understanding that this is the design choice of Boeing in its new aircrafts.

I do not wish to discuss how Airbus and Boeing made their design decisions, but rather see if there has been performed a study on what interface is preferred by pilots, eventually differentiating among private/commercial pilots or Airbus/Boeing certified pilots or even pure civil/(former) military pilots.

Does any of you have any reference?

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    I predict that most pilots will prefer whichever style they're most used to. – Henning Makholm Mar 28 '14 at 12:46
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    A good place to start is this text "Human Factors in Aviation" If I recall, there was a chapter in there on ergonomics with some studies cited. – Canuk Mar 28 '14 at 15:38
  • @Canuk, I had a look through the references and the chapters, but to me it seems more focused on the physical aspects (levers/buttons/instruments locations and such) rather than the fly-by-wire "handling qualities" (if you allow this terminology) – Federico Mar 28 '14 at 15:46
  • @Federico, I had the wrong book, "Human Factors in Flight" ( is what I was thinking. There is a chapter on "Displays and Controls" and while the text is admittedly dated, it offers this unattributed sentence about the Airbus "...these features...have proved quite controversial, it must be admitted that most pilots who fly these aircraft, like them very much." (p.264) I think it might be hard to find an actual study since it sounds like what you're after is a subjective opinion, however, perhaps a study exists from an ergonomic or human-factors related perspective. – Canuk Mar 28 '14 at 19:23
  • related discussion. It is not as simple as choice #1 or choice #2. on the pitch axe, C* blend rate control and load factor. Consider also the difficulty of enhanced stability – Manu H Oct 20 '14 at 13:46

I have no study to refer to, but I expect the results to differ very much from group to group.

For airline operations, I imagine the objective of the pilot is often to maintain a constant attitude, varied with a smooth transition to another attitude. This would be easy to achieve with the first option you describe.

For military operations, I think a rapid feedback is desired. This aligns better with the seconds option you describe.

When you would perform a study under pilots, the response you'll get will very likely be that they prefer whatever they are used to at the moment.

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    The second option does not provide any faster feedback. In fact, shortest reaction times are achieved by aerodynamically unstable designs, but for those, only the first option is actually usable. – Jan Hudec Mar 20 '17 at 19:21

Yes there have been, but quite some time ago so they may be hard to find in our present day Google world. Studies about the pilot-in-the-loop, who controls the aircraft by interpreting and reacting to the change in the outside world as function of their inputs. But these studies concentrated upon what configuration yields the most rapid and accurate result, and not on what the preference is. I was participant in the graduation project of one of my fellow university students in 1988: using a spring loaded side stick, place a representation of a satellite robot arm into a receptor bay, with different controller configurations. Stick displacement or applied stick force = robot arm rate, or robot arm position.

Force is often overlooked in these discussions, despite it providing an immediate feedback without having to look at where your hand is. We don't have direct position sensors in our hands! Rate feedback is an issue when you want to control a position: the extra integration that your brain needs to perform causes a time delay and estimation errors. Depending on the frequency response of the signals of course, the satellite end effector was very slow and it was very tedious to do anything with it using rate feedback.

We seem to control best when we are presented with an environment that replicates the forces of physics that we are built for. The F16 uses force feedback: the original stick did not move, input was how hard the pilot pulled on it. Then they started coming back with bent side sticks from Really Pulling Hard to out-turn the other guy, and the sticks became moveable, loaded by a stiff spring, but giving an extra force cue when the end of stick deflection was reached. I bet that General Dynamics did not design this control system with the preference of the generic pilot in mind though.

Boeings design choice is the one with the least amount of possible discussion risk: pilots have learned to integrate aircraft rate feedback (from their sensory organs), and have learned certain responses in order to control the aircraft. Airbus seems to be more inclined to incorporate recent research. Like you say, both make excellent aircraft with an excellent safety reputation and dissing one or the other would be a bit childish, really.

  • I asked about the signal, not the feedback. Airbus has no feedback, for example. – Federico Apr 29 '17 at 6:38
  • And feedback of environmental information is not what happens in the task of controlling an aeroplane? – Koyovis Apr 29 '17 at 10:20
  • Your last paragraph earns this answer +1, and more plusses were I allowed. – KorvinStarmast May 1 '17 at 14:55
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    Thanks @KorvinStarmast. For experts like yourself there is no issue with how aircraft behave, you guys get right on top of anything. But there are 1,400 new airliners delivered every year, each requiring between 4 and 8 flight crews. Up to 20,000 new pilots per year, and a good portion of those are brand new pilots. Research into how zero-hour pilots carry out a pilot-in-the-loop task is very beneficial. – Koyovis May 2 '17 at 12:13

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