Mode confusion and automation surprises in aviation raise questions about the design of flight deck interfaces. Prior research investigated the use of the current interfaces and how they can impact the pilot's awareness of modes, and proposed design solutions to reduce mode confusions by improving feedback and interaction with modes. This paper explores a novel design that brings together mode control and feedback in a single interface. The interface aims to reduce mode confusions. Moreover, the paper highlights 5 key dimensions that influenced the design. In the future, we intend to evaluate the proposed interface to validate its benefits.
While the basic philosophy of the autoflight system in aircraft has become more and more complex in the past years, the way the modes are displayed to pilots has not evolved much. This can make it more dificult for pilots to interpret current flight modes and to be aware of the behavior of the aircraft. play presenting the modes used by the aircraft. Thus it informs the pilot of the current behavior and state of the autoflight system. The current design of the FMA is a basic layout located at the top of the Primary Flight
by the system) and ”armed” modes (waiting to be active when the requirements are met) through a table divided into three columns for autothrottle and autopilot modes. Mode changes are indicated by a white box outline around the relevant mode for ten seconds.
understand the state of the autoflight system [ 1, 2]. Pilots use other interfaces of the flight deck to find information they need to increase their situation awareness, and those interfaces provide, in most cases, reliable information at a lower cognitive cost than the FMA [3]. Palmer [1]
not allow the pilot to be fully aware of the system status. crew’s interpretation of the system state from the actual © 2023 Copyright for this paper by its authors. Use permitted under Creative Commons License Over the years, accidents have allowed us to question the design of the flight deck and to identify interface problems. As flight deck interface issues have been identified, a number of researchers have proposed changes to various interfaces to reduce the mode confusion of pilots. Those new designs aim at providing better feedback for pilots both for input and output.
modes are engaged in order to improve the feedback on the control interface. Boorman et al. [17] developed an interface design of the MCP in order to reduce confusion. This new interface focuses on targets rather than modes and gives a clear indication of targets and sources. It was evaluated by 17 pilots [18, 19]. Participants were asked to perform tasks and answered questions about autoflight behavior. Results indicated that the ability to assess the new interface to understand the system’s objectives is better than the current interface, although some issues emerged. Rouwhorst et al. [20] presented a touch screen control panel to select targets and engage advanced modes through novel interactions. Hutchins [21] proposed the Integrated Mode Management Interface (IMMI), an interface consisting of a vertical mode manager and a lateral mode manager, which replace the mode controller and provide feedback about the modes of the system and its behavior. Li et al. [22] explored automation feedback design and proposed to move the FMA to the MCP’s position. Results showed that moving the FMA next to the MCP could increase pilots’ situation awareness.
Another possibility to reduce mode confusion is to
augment the feedback by changing the way modes
are displayed and by providing better indications
about the behavior of the aircraft. The use of icons
to indicate autoflight modes and their behaviors has
been studied in the literature [21, 23]. Other studies
have focused on designing a new FMA format. For
example, Feary et al. [24] proposed new FMA labels that
indicate the purpose of the system rather than what
the aircraft controls. Horn et al. [
interfaces to reduce mode confusion. Focusing on the presentation of feedback and engagement of modes seems a promising venue to address issues of situational awareness and mode confusion.
Palmer [1] about the physical separation between the MCP used to engage modes and the FMA by merging the MCP and the FMA, i.e. making the FMA interactive, and hence to provide feedback directly at the location of the pilot’s action. To remedy the lack of awareness, we applied a user-centered design process. First, we conducted a series of activities such as interviews with pilots, observation sessions, and focus groups with experts to better understand pilots’ behavior in real flight contexts. and SPD. The AUTO mode corresponds to a state where We propose a new design that brings together two cur- the aircraft manages automatically the thrust. In the rently separate interfaces in the cockpit, the MCP and the SPD mode, the aircraft is maintaining a speed target. FMA: the Interactive Flight Mode Annunciator (IFMA).
IFMA is a touch-screen interface allowing the pilots to A specific colour highlights the status of each mode manage autoflight modes and providing feedback about (Fig. 1) : the modes used by the system (Fig. 1). It allows pilots to understand what the aircraft is doing, what the active modes are, who has control of the targets and which automation is engaged. • Active: green box and label. • Armed: white box and label. • Inactive and engageable: light gray box and label. • Inactive but not engageable: dark grey box and label.
The philosophy of the FMA is kept in the IFMA which is divided into four parts. From left to right (Fig. 1) : vertical guidance, lateral guidance, speed guidance and the status of the automation. As for the three columns of guidance, the first row corresponds to the modes where the target is managed by the system (following the flight plan) and the second row corresponds to the modes where the target is selected by the pilot (maintaining or tracking heading, altitude, speed). The third difers across all columns.
All modes are visible on the interface and represented by a label associated with a box. Names of modes differ depending on the manufacturer, so we decided to standardize them in our interface:
For example, Figure 1 indicates the modes ALT, HDG and SPD are active, which means they are the modes used by the autoflight system. LNAV is armed, which means that the mode will become active once the necessary conditions for its activation are met, and thus the mode HDG will become inactive. VS and AUTO are inactive and engageable : they will be active or armed if the pilot decides to engage them. VNAV, APPR and LOC are inactive but not engageable because some conditions are not fulfilled (VNAV can only be engaged when LNAV is active, and LOC and APPR will only be engageable when the aircraft is close to the airport, thus avoiding the capture of wrong signals).
All modes with which the pilot can interact are represented on the interface. This overview of modes with color coding allows pilots to be aware of engaged modes and those which are not, as well as which modes they can engage and those they cannot engage.
ways of interaction to control modes and new forms of feedback for autoflight modes. We focused on two ideas that were evaluated by pilots through an online survey. The result allowed us to focus our approach on merging the MCP with the FMA i.e. merging the action and the verification in the same interface.
Vertical guidance There are 3 main modes: VNAV for the automatic vertical navigation ; ALT to maintain an altitude target ; VS to climb or descent with a specific vertical speed. Two additional modes (OP CLB and OP DES) have a diferent design because they represent a specific 4.2. Interactions - How to control modes behavior in transit to climb or descent by maintaining At the bottom of the panel, there are a thumb wheel and a speed and those are modes implicitly triggered by the three knobs. These buttons allow the pilot to modify the engagement of the ALT mode. They both are represented value of the vertical speed, altitude, heading and speed by a solid green box on the left of the ALT mode (Fig. 2). targets (from left to right in Figure 1). The thumb wheel, which allows managing the vertical speed target, is difLateral guidance There are 4 modes: LNAV for the ferent from the other three knobs because they are not automatic lateral navigation ; HDG to maintain a heading used in the same way. A knob can be turned and pushed target ; LOC to follow the localizer and APPR to engage when the thumb wheel can only be turned. We chose this LOC and GS, the mode to follow the glide slope. design since pilots do not need to hold a current vertical speed because they choose the target before engaging Speed/Thrust guidance We decided to highly the mode, contrary to the heading, the altitude and the simplify the autothrust modes in only 2 modes : AUTO speed they may need to hold at a current value. • Turn a knob: select the target of the parameter
corresponding to the knob. • Press a knob: maintain the current value of the
parameter corresponding to the knob. • Turn the thumb wheel: select the target of the
vertical speed. • Press a mode (or the status of automation): en
gage the mode or the status.
OP CLB and OP DES) and VS modes by pressing the
box must be preceded by the selection of a target. If the
pilot presses one of these modes without a preselected
target, a brief orange flash appears on the screen to
indicate to the pilot that the action has not led to a
result. This solution, inspired by ”Red Alert” [
Furthermore, if the pilot preselects a target, but the the autothrust modes have been simplified (only two in associated mode is not engaged within 10 seconds, then the IFMA) and do not reflect modes related to thrust. This the preselection will be cleared. This time has been aspect needs more thought. Moreover, there is no possichosen arbitrarily and user studies should be conducted bility in the IFMA to switch between Heading and Track to identify the ideal timing. We are aware that pilots modes or between Vertical Speed and Flight Path Angle sometimes preselect targets and a more or less long time modes. We need to investigate how to add these two is spent between the preselection of the target and the features while keeping the consistency of the interface. engagement of the associated mode, but we have chosen This question is related to the scalability, which needd to to make the ”unused” targets disappear to simplify be considered: is it possible to add new modeswhileby as much as possible the reading of the IFMA by the pilots. keeping the current characteristics of the IFMA? Finally, we are aware of the problems related to using touch
To disengage a mode, the pilot will have to engage screens in a cockpit [
are beneficial in the IFMA compared to existing systems
(although this will need to be evaluated in a user study
with pilots). These points are listed below and some of
them are inspired by the cognitive dimensions of
Blackwell and Green [
Visibility interface.
All modes are permanently visible on the