3
$\begingroup$

I sometimes have the feeling that Airbus with augmented control are more prone to landing incidents (hard landings and runway excursions) than other models of aircraft with conventional controls.

Is there anywhere I could find data to perhaps back see if this might be correct? Such as a list of all landing incidents in Europe or the United States?

$\endgroup$
  • $\begingroup$ avherald has a list of incidents, you can try looking through that (not all incidents are recorded) $\endgroup$ – ratchet freak May 28 '14 at 10:19
  • $\begingroup$ @ratchetfreak that's the problem with avherald :/ $\endgroup$ – Thunderstrike May 28 '14 at 10:21
  • 1
    $\begingroup$ Interesting question, my feeling is exactly the opposite. Not only would we need a list of landing incidents per aircraft type (manufacturer), we would also need to know the number of flights per aircraft type to correct for differences in usage. $\endgroup$ – DeltaLima May 28 '14 at 13:53
  • 3
    $\begingroup$ You'd have to do an enormous amount of data correction - winds, pilot experience, etc in order for this to be of any practical use, and I don't think that this is something that can be easily 'proven' $\endgroup$ – Aaron May 28 '14 at 14:19
  • 1
    $\begingroup$ Even if you find the data you're looking for, you need to be very careful with the analysis. If you're not an expert in statistics, your answer is unlikely to be valid. It sounds very much that you have a pre-conceived notion of what the answer should be and that you're looking for data to support that hypothesis. It's very easy to massage statistics, consciously or unconsciously, to get the result you're looking for. $\endgroup$ – David Richerby May 30 '14 at 9:29
1
$\begingroup$

NASA collects statistics on aviation incidents through its Aviation Safety Reporting System, and the ASRS database is searchable online. You can specify criteria such as the flight phase and aircraft type in your search.

| improve this answer | |
$\endgroup$
  • 2
    $\begingroup$ To actually address your 'feeling' of course you would need to combine this with statistics such as the number of landings made by each kind of plane. $\endgroup$ – DJClayworth May 29 '14 at 19:54
0
$\begingroup$

I ... feel ... [aircraft] with augmented control are more prone to landing incidents

The Airbus and Boeing 787 FBW with augmented control have some similarities.

This 2012 ICAS paper: "FLY-BY-WIRE AUGMENTED MANUAL CONTROL - BASIC DESIGN CONSIDERATIONS" discusses Boeing and Airbus augmented control systems and its effect on piloting technique

See 4.2.

4.2 Piloting Technique for Disturbance Compensation

The influence of manual augmented control on the optimal piloting technique is significant. For conventionally controlled aircraft the task of stabilizing the aircraft on the desired flight path after an external disturbance is left to the pilot, but the pilot has no suitable indication of flight path deviation on his PFD. For that reason pilots are still used to react to a change of attitude angles. As the attitude angles are easy to derive either from the outside view or from the PFD that puts the main focus on the aircraft attitude control, the main control references for manual control are still the pitch angle for longitudinal control and the bank angle for lateral control.

However, the application of manual augmented control in modern FBW aircraft has influenced the distribution of tasks between the pilot and the flight control system with respect to the compensation for external disturbances.

For lateral motion control, Airbus uses a roll rate command and bank angle hold system which actively tries to keep the bank angle at zero after a lateral disturbance. The B777 FBW lateral control is basically a Direct Control mode without feedbacks and a roll attitude hold feature, so the airplane responds to a lateral disturbance like a conventionally controlled airplane. The B787 has an integrated lateral/directional control algorithm that provides basically roll rate command/ roll attitude hold control, similar to the Airbus design. The latter type of designs provide more roll attitude stiffness and thus require less pilot compensation for external disturbances. For those control algorithms a strong reaction of the pilot in response to rotational rates or attitude angle changes might lead to adverse effects due to a significant interaction between pilot and the flight control algorithm.

In 2010 DLR performed a study on a Airbus A330 Full Flight Simulator, where the aircraft was disturbed by a simulated wake vortex encounter while the pilots revealed that numerous pilots aggravated the impact of the wake vortex on the aircraft response by generating to strong and to abrupt inputs on the stick, although they were informed that a wake encounter could occur [23]. This was especially observed for pilots with little experience on FBW aircraft. The final report recommends that the pilots should react to the lateral and vertical flight path deviation with extremely smooth inputs on the stick rather than trying to overcompensate for the change in attitude angles [23]. These recommendations are similar to those given by Airbus for manual control during wake-vortex encounters [21].

Hence, the piloting technique should change from a continuous compensatory control to an intermittent control strategy, because the short-term control task of continuous pitch and roll attitude stabilization is performed by the control algorithm. In many current airline training programs no emphasis is put on the adaptation of the piloting technique that is needed to safely operate a FBW aircraft with manual augmented control in case of external disturbances. It seems that in most cases the pilot still uses pitch angle as his primary control variable. During the simulator study performed by Gautrey several pilots commented on the desirability of a flight path vector display, especially for the unconventional systems without speed stability, because this is the parameter which they are ultimately trying to control [12]. For the majority of existing Airbus FBW aircraft the flight path vector symbol is only available in the PFD, if certain autopilot modes are triggered. However, flight path information is displayed in the head-up display which can be optionally ordered for every Airbus FBW aircraft.

| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.