Flight Mechanics, Flight Control and Aeroelasticity

Pilot-Centered Design of a Longitudinal Acceleration Command System for Augmented Manual Flight Control (nxControl)

The project „nxControl“ will developa new control command system for longitudinal acceleration  (nx command) using thrust and speedbrakes in flight as well as thrust reverser and brakes on ground, improving flight path control in manual flight. The project is funded by the Deutsche Forschungsgemeinschaft (DFG). The interdisciplinary project focuses on both the technical and the psychological aspects of a new control system. Therefore the chair of Flight Mechanics, Flight Control and Aeroelasticity (FMRA) will design the controller and the chair of Work, Engineering and Organizational Psychology (AIO) will develop the human machine interface and analyze the impact of the new control system on pilot workload. The whole command system will be tested and verified using the research simulator SEPHIR.


Increasing air traffic raises the requirements on future flight trajectories coupled with the necessity to follow a flight path with higher precision. These requirements must be fulfilled in automatic as well as in manual flight. This leads to increased pilot workload especially when all control devices that affect the state of the total energy (potential, kinetic energy), such as thrust and speedbrakes, are commanded.

The project aims to assist the pilots by developing an innovative longitudinal acceleration control command system (nxControl). The functionality of the nxControl command system has to be comprehensible and transparent to the pilots in order to ensure an adequate situational awareness for monitoring and operating the controller, to increase pilots’ acceptance, and to minimize training effort for more precise flight path control. To achieve this, the development of the nxControl function shall be based on a pilot-centered design approach for both the controller as well as the human-machine interface (display and inceptor).

Objectives and Methods

The goal of the project is to improve flight path control in manual flight by the development of a longitudinal acceleration control command system (nx command) that uses thrust and speedbrakes in flight as well as thrust reverser and brakes on ground.

Following the pilot-centered design approach, the prevalent mental model of the pilot regarding flight path control of an aircraft in longitudinal direction will be determined. This information is used to define the characteristics and the functionality of the nx-Controller in detail. Furthermore, the effects of the higher degree of automation on the pilots and the resulting consequences for the concept and design of the human-machine interface will be investigated.

Subsequently, the nx-Control augmentation system that computes the command values for the energy-related control devices will be designed and implemented. Multiple actuation values are available for just one control value which leads to an over-determination of the system. This is known as “Control Allocation” problem which has to be solved for this case. FMRA uses a nonlinear simulation model of the VFW614-ATD, which will be linearized for initial linear controller design. The linear controller will be the basis for the following nonlinear controller design.

Simultaneously, a concept for the human-machine interface for nx-Control will be designed. Both controller and human-machine interface will be integrated into the flight simulator SEPHIR for proof of concept. Simulator test campaigns with experienced airline pilots will be conducted to confirm the hypotheses that nx control:

  1. leads to a higher precision in manual flight regarding preset and complex flight paths,
  2. does not add pilot workload due to higher complexity and
  3. has no negative impact on the situational awareness due to the higher degree of automation.

Project Plan

WP1Concept development for the flight guidance system with nx command (FMRA, AIO)
WP2Design of the nx command controller system (FMRA)
WP3Development of the human machine interface (AIO)
WP4Integration into the research simulator (FMRA, AIO)
WP5Flight simulator campaigns with pilots (FMRA, AIO)
WP6Conclusions and documentation (FMRA, AIO)