Lyman, re #407 "The Airbus side stick system lacks the "position of the control surface feed back loop" to the pilot. We have no easy method to see how much control surface deflection is required to satisfy our side stick input. It is very useful for an experienced crew to know."
The MD-80 and BAe146 with conventional yokes lack positional feedback …
The issue is the lack force feedback, either actual or artificial from control input and trim position. This stick-trim force provides a measure of deviation from trim speed.
In a conventional aircraft the residual force has to be zeroed manually; in some FBW aircraft it is removed with automatic trim follow up (Airbus). In such systems, either side-stick or conventional column, it is normal to provide a centring force indicating an error from the null input.
FBW systems are not ‘wrong’ etc, just different, and may require an alternative means of detecting speed error and/or (mis)trim position. This is normally via instrument displays - the ASI; note industry concerns over poor instrument flying skills and dependency on autothrust, there is less requirement to ‘look after’ speed.
With the lack of an airspeed display, a FBW aircraft has no backup of sensed trimmed position as with a conventional aircraft (no stick-force for trim speed error), thus it is important to look at the physical trim indication and be aware of the need to null any stick input when the desired flight path is achieved.
As an example; - the need for a small pitch change when flying without an airspeed display.
In a conventional aircraft the pilot moves the stick and in time will have a force proportional to the trim speed error – large error, high force, this is a cue to trim and/or relax the input.
In a FBW aircraft there is no need to maintain the input once the flight path/attitude has been achieved, the side stick should be centred (a reversed sense of movement) and, providing the auto trim has followed up, the aircraft will maintain the flight path/attitude (may depend on control law) – and the resultant speed will depend on thrust, configuration, etc, etc (no autothrust).
As a hypothesis, would a novice pilot trained on conventional controls (little hands-on experience in FBW aircraft) ‘revert to type’ – using conventional control input strategy when faced with a challenging situation in a FBW aircraft, i.e maintain stick input/position?