Table 5-2. Specified Colors for Certain Display Features Display Feature Color Set 1 Color Set 2 Fixed reference symbols White Yellow1 Current data, values White Green Armed modes White Cyan Selected data, values Green Cyan Selected heading Magenta2 Cyan Active route/flight plan Magenta White 1 Use of the color yellow for functions other than flightcrew alerting should be limited and should not adversely affect flightcrew alerting.
2 In Color Set 1, magenta is intended to be associated with those analog parameters that constitute “fly to” or “keep centered” type information.
5.8.7 The following color pairs should be avoided:
• Saturated red and blue.
• Saturated red and green.
• Saturated blue and green.
• Saturated yellow and green.
• Yellow on purple.
• Yellow on green.
• Yellow on white.
• Magenta on green.
• Magenta on black (although this may be acceptable for lower criticality items).
• Green on white.
• Blue on black.
• Red on black.
Note: For further information on this subject, see FAA Report No. DOT/FAA/CT 03/05 HF-STD-001, Human Factors Design Standard (HFDS): For Acquisition of Commercial Off-the-Shelf Subsystems, Non-Developmental Items, and Developmental Systems.
5.8.8 When background color is used (for example, gray), it should not impair the use of the overlaid information elements. Labels, display-based controls, menus, symbols, and graphics should all remain identifiable and distinguishable. The use of background color 5-10
should conform to the overall flight deck philosophies for color usage and information management. If texturing is used to create a background, it should not result in loss of readability of the symbols overlaid on it, nor should it increase visual clutter or pilot information access time. Transparency is a means of seeing a background information element through a foreground one; the use of transparency should be minimized because it may increase pilot interpretation time or errors.
5.8.9 Requiring the flightcrew to discriminate between shades of the same color for distinct meaning is not recommended. The use of pure blue should not be used for important information because it has low luminance on many display technologies (for example, CRT and LCD).
5.8.10 Any foreseeable change in symbol size should ensure correct color interpretation. For example, the symbol needs to be sufficiently large so the pilot can interpret the correct color.
5.9 Dynamic (Graphic) Information Elements on a Display.
The following paragraphs cover the motion of graphic information elements on a display, such as the indices on a tape display. Graphic objects that translate or rotate should do so smoothly without distracting or objectionable jitter, jerkiness, or ratcheting effects. Data update rates for information elements used in direct airplane or powerplant manual control tasks (such as attitude, engine parameters, etc.) equal to or greater than 15 Hertz have been found to be acceptable. Any lag introduced by the display system should be consistent with the airplane control task associated with that parameter. In particular, display system lag (including the sensor) for attitude that does not exceed a first order equivalent time constant of 100 milliseconds for airplanes with conventional control system response is generally acceptable.
5.9.1 Movement of display information elements should not blur, shimmer, or produce unintended dynamic effects such that the image becomes distracting or difficult to interpret. Filtering or coasting of data intended to smooth the motion of display elements should not introduce significant positioning errors or create system lag that makes it difficult to perform the intended task.
5.9.2 When a symbol reaches the limit of its allowed range of motion, the symbol should either slide from view, change visual characteristics, or be self-evident that further deflection is impossible.
5.9.3 Dynamic information should not appreciably change shape or color as it moves. Objects that change sizes (for example, as the map range changes) should not cause confusion as to their meaning and should remain consistent throughout their size range. At all sizes the objects should meet the guidance of this chapter as applicable (that is, the objects should be discernible, legible, identifiable, placed accurately, not distracting, etc.).
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5.10 Sharing Information on a Display.
There are three primary methods of sharing information on a given display. First, the information may be overlayed or combined, such as when traffic alert and collision avoidance system (TCAS) information is overlayed on a map display. Second, the information can be time shared so that the pilot toggles between functions, one at a time. Third, the information may be displayed in separate physical areas or windows that are concurrently displayed. Regardless of the method of information sharing, care should be taken to ensure that information that is out prioritized, but is needed, can be recovered, and that it will not be needed more quickly than it can be recovered.
5.10.1 Overlays and Combined Information Elements.
5.10.1.1 When information is graphically overlaid over other information (for example, an airplane symbol over a waypoint symbol) in the same location on a display, the loss of information availability, information access times, and potential for confusion should be minimized.
5.10.1.2 When information obscures other information it should be shown that the obscured information is either not needed when it is obscured or can be rapidly recovered. Needed information should not be obscured. This may be accomplished by protecting certain areas of the display.
5.10.1.3 If information is integrated with other information on a display, the projection, placement accuracy, directional orientation, and display data ranges should all be consistent (for example, when traffic or weather is integrated with navigation information). When information elements temporarily obscure other information (for example, pop-up menus or windows), the resultant loss of information should not cause a hazard in accordance with the obscured information’s intended function.
5.10.1.4 Time Sharing.
5.10.1.4.1 For guidance on full-time vs. part-time displays, see paragraph 6.3.3 of this AC.
5.10.1.4.2 Any information that should or must be continuously monitored by the flightcrew should be displayed at all times (for example, attitude).
5.10.1.4.3 Whether or not information may be time shared depends on how easily it can be retrieved in normal, non-normal, and emergency operations.
Information for a given performance monitoring task may be time shared if the method of switching back and forth does not jeopardize the performance monitoring task.
5.10.1.4.4 Generally, system information, planning, and other information not necessary for the pilot tasks can be time shared.
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5.10.2 Separating Information Visually.
When different information elements are adjacent to each other on a display, the elements should be separated visually so the pilots can easily distinguish between them.
Visual separation can be achieved with, for example, spacing, delimiters, or shading in accordance with the overall flight deck information management philosophy. Required information presented in reversionary or compacted display modes following a display failure should still be uncluttered and still allow acceptable information access time.
5.10.3 Clutter and De-Clutter.
5.10.3.1 A cluttered display presents an excessive number or variety of symbols, colors, and/or other unnecessary information and, depending on the situation, may interfere with the flight task or operation. A cluttered display causes increased flightcrew processing time for display interpretation, and may detract from the interpretation of information necessary to navigate and fly the airplane. Information should be displayed so that clutter is minimized.
5.10.3.2 To enhance pilot performance, a means should be considered to de-clutter the display. For example, an attitude indicator may automatically de clutter when the airplane is at an unusual attitude to aid the pilot in recovery from the unusual attitude by removing unnecessary information and retaining information required for the flightcrew to recover the airplane.
5.11 Annunciations and Indications.
5.11.1 General.
Annunciations and indications include annunciator switches, messages, prompts, flags, and status or mode indications that either are on the flight deck display itself, or control a flight deck display. See § 25.1322 and AC 25.1302-1 for information regarding specific annunciations and indications such as warning, caution, and advisory level alerts.
5.11.1.1 Annunciations and indications should be operationally relevant and limited to minimize the adverse effects on flightcrew workload.
5.11.1.2 Annunciations and indications should be clear, unambiguous, timely, and consistent with the flight deck design philosophy. When an annunciation is provided for the status or mode of a system, it is recommended that the annunciation indicate the actual state of the system and not just the position or selection of a switch. Annunciations should only be indicated while the condition exists.
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5.11.2 Location.
Annunciations and indications should be consistently located in a specific area of the electronic display. Annunciations that may require immediate flightcrew awareness should be located in the flightcrew's forward/primary field of view.
5.11.3 Managing Messages and Prompts.
The following general guidance applies to all messages and prompts:
5.11.3.1 When messages are currently being displayed and there are additional messages in the queue that are not currently displayed, there should be an indication that the additional messages exist.
5.11.3.2 Within levels of urgency, messages should be displayed in logical order.
In many cases, the order of occurrence of events has been found to be the most logical way to place the messages in order.
5.11.3.3 See § 25.1322 and AC 25.1302-1 for information on warning, caution, and advisory alerts.
5.11.3.4 A text change by itself should not be used as an attention-getting cue (for example, to annunciate mode changes).
5.11.4 Blinking.
Blinking information elements such as readouts or pointers are effective methods of annunciation. However, the use of blinking should be limited because it can be distracting and excessive use reduces the attention getting effectiveness. Blinking rates between 0.8 and 4.0 Hertz should be used, depending on the display technology and the compromise between urgency and distraction. If blinking of an information element can occur for more than approximately 10 seconds, a means to cancel the blinking should be provided.
5.11.5 Use of Imaging.
This paragraph provides guidance on the use of images that depict a specific portion of the airplane environment. These images may be static or continuously updated. Imaging includes weather radar returns, terrain depictions, forecast weather maps, video, enhanced vision displays, and synthetic vision displays. Images may be generated from databases or by sensors.
5.11.5.1 Images should be of sufficient size and include sufficient detail to meet the intended function. The pilots should be able to readily distinguish the features depicted. Images should be oriented in such a way that their presentation is easily interpreted. All images, but especially dynamic images, should be located or controllable so they do not distract the pilots from required tasks. The source and intended function of the image and the level of operational approval for using the image should be provided to the pilots. This can be accomplished using the airplane flight manual 5-14
(AFM), image location, adequate labeling, distinct texturing, or other means.
5.11.5.2 Image distortion should not compromise image interpretation. Images meant to provide information about depth (for example, three-dimensional type perspective displays) should provide adequate depth information to meet the intended function.
5.11.5.3 Dynamic images should meet the guidance in paragraph 5.9 of this chapter. The overall system lag time of a dynamic image relative to real time should not cause flightcrew misinterpretation or lead to a potentially hazardous condition. Image failure, freezing, coasting, or color changes should not be misleading and should be considered during the safety analysis.
5.11.5.4 When overlaying coded information elements over images, the information elements should be readily identifiable and distinguishable for all foreseeable conditions of the underlying image and range of motion.
The information elements should not obscure necessary information contained in the image. The information should be depicted with the appropriate size, shape, and placement accuracy to avoid being misleading. They should retain and maintain their shape, size, and color for all foreseeable conditions of the underlying image and range of motion.
5.11.5.5 When fusing or overlaying multiple images, the resultant combined image should meet its intended function despite any differences in image quality, projection, data update rates, sensitivity to sunlight, data latency, or sensor alignment algorithms. When conforming an image to the outside world, such as on a HUD, the image should not obscure or significantly hinder the flightcrew’s ability to detect real world objects. An independent brightness control of the image may help satisfy this guideline. Image elements that correlate or highlight real world objects should be sufficiently coincident to avoid interpretation error or significantly increase interpretation time.
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CHAPTER 6. ORGANIZING ELECTRONIC DISPLAY INFORMATION ELEMENTS
6.1 Organizing Information Elements.
This chapter provides guidance for integrating information into the flight deck related to managing the location of information, arranging the display, windowing, configuring and reconfiguring the display, and selecting the sensors across the flight deck displays.
The following paragraphs include guidance for various flight deck configurations from dedicated electronic displays for the attitude director indicator and the horizontal situation indicator to larger display sizes that use windowing techniques to display various functionalities on one display area. In some flight decks the primary flight information and the navigation display are examples of information that is displayed using windowing techniques. Chapter 5 of this AC provides guidance for information elements including text, labels, symbols, graphics, and other depictions (such as video) in isolation and combination.
6.2 Types and Arrangement of Display Information.
This paragraph provides guidance for the arrangement and location of categories of information. The categories of information include the following:
• Primary flight information including attitude, airspeed, altitude, and heading.
• Powerplant information that covers functions relating to propulsion.
• Other information.
6.2.1 Placement—General Information.
The position of a message or symbol within a display conveys meaning to the pilot.
Without the consistent or repeatable location of a symbol in a specific area of the electronic display, interpretation error and response times may increase. The following information should be placed in a consistent location under normal conditions:
6.2.1.1 Primary flight information. (See paragraph 6.2.3 in this chapter and appendix A of this AC.)
6.2.1.2 Powerplant information. (See paragraph 6.2.4 in this chapter and appendix B of this AC.)
6.2.1.3 Flightcrew alerts. Each flightcrew alert should be displayed in a specific location or in a central flightcrew alert area.
6.2.1.4 Autopilot and flight director modes of operation.
6.2.1.5 Lateral and vertical path deviation indicators.
6.2.1.6 Radio altitude indications.
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6.2.1.7 Failure flags should be presented in the location of the information they reference or replace.
6.2.1.8 Data labels for navigation, traffic, airplane system, and other information should be placed in a consistent position relative to the information they are labeling.
6.2.1.9 Supporting data for other information, such as bugs and limit markings, should be consistently positioned relative to the information they support.
6.2.1.10 Features on electronic moving map displays (for example, very high frequency omnirange stations (VORs), waypoints, etc.) relative to the current airplane position. In addition, the features should be placed on a constant scale for each range selected.
6.2.1.11 Segment of flight information relative to similar information or other segments.
6.2.2 Placement—Controls and Indications.
When a control or indication occurs in multiple places (for example a “Return” control on multiple pages of a flight management function), the control or indication should be located consistently for all occurrences.
6.2.3 Arrangement—Basic T Information.
6.2.3.1 Section 25.1321(b) includes requirements for the “Basic T” arrangement of certain information required by § 25.1303(b).
6.2.3.2 The following paragraphs provide guidance for the Basic T arrangement.
This guidance applies to single and multiple display surfaces.
6.2.3.2.1 The Basic T information should be displayed continuously, directly in front of each flightcrew member under normal (that is, no display system failure) conditions. Section 25.1321(b) requires that flight instruments required by § 25.1303 must be grouped on the instrument panel and centered as nearly as practicable about the vertical plane of the pilot’s forward vision.
6.2.3.2.2 The Basic T arrangement applies to the primary display of attitude, airspeed, altitude, and direction of flight. Depending on the flight deck design, there may be more than one indication of the Basic T information elements in front of a pilot. For example, heading information may appear on backup displays, HUDs, and moving map displays. The primary airspeed, altitude, and direction indications are the respective display indications closest to the primary attitude indication.
6.2.3.2.3 The primary attitude indication should be centered about the plane of the flightcrew’s forward vision. This should be measured from the DEP at the 6-2
flightcrew station (see related regulation). If located on the main instrument panel, the primary attitude indication must be in the top center position (§ 25.1321(b)). The attitude indication should be placed so that the display is unobstructed under all flight conditions. See SAE ARP4102/7 for additional information.
6.2.3.2.4 The primary airspeed, altitude, and direction of flight indications should be located adjacent to the primary attitude indication. Information elements placed within, overlaid, or between these indications, such as lateral and vertical deviation, are acceptable when they are relevant to respective airspeed, altitude, or directional indications used for accomplishing the basic flying task, and are shown to not disrupt the normal crosscheck or decrease manual flying performance.
6.2.3.2.5 The instrument that most effectively indicates airspeed must be adjacent to and directly to the left of the primary attitude indication (§ 25.1321(b)).
The center of the airspeed indication should be aligned with the center of the attitude indication. For airspeed indications, vertical deviations have been found acceptable up to 15° below and to 10° above when measured from the direct horizontal position of the airplane waterline reference symbol. For tape type airspeed indications, the center of the indication is defined as the center of the current airspeed status reference.
6.2.3.2.6 Parameters related to the primary airspeed indication, such as reference speeds or Mach indication, should be displayed to the left of the primary attitude indication.
6.2.3.2.7 The instrument that most effectively indicates altitude must be located adjacent and directly to the right of the primary attitude indication (§ 25.1321(b)). The center of the altitude indication should be aligned with the center of the attitude indication. For altitude indications, vertical deviations have been found acceptable up to 15° below to 10° above when measured from the direct horizontal position of the airplane waterline reference symbol. For tape type altitude indications, the center of the indication is defined as the center of the current altitude status reference.
6.2.3.2.8 Parameters related to the primary altitude indication, such as the barometric setting or the primary vertical speed indication, should be displayed to the right of the primary altitude indication.
6.2.3.2.9 The instrument that most effectively indicates direction of flight must be located adjacent to and directly below the primary attitude indication (§ 25.1321(b)). The center of the direction of flight indication should be aligned with the center of the attitude indication. The center of the direction of flight indication is defined as the center of the current direction of flight status reference.
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6.2.3.2.10 Parameters related to the primary direction of flight indication, such as the reference (that is, magnetic or true) or the localizer deviation should be displayed below the primary attitude indication.
6.2.3.2.11 If an applicant seeks approval of alternative instrument arrangements by equivalent safety under § 21.21(b)(1), the FAA will normally require well-founded research, or relevant service experience from military, foreign, or other sources to substantiate the applicant’s proposed compensating factors.
6.2.4 Arrangement—Powerplant Information.
6.2.4.1 Required engine indications necessary to set and monitor engine thrust or power should be continuously displayed in the flightcrew’s primary field of view, unless the applicant can demonstrate that this is not necessary (see the guidance in paragraph 6.3.3 of this chapter and appendix B of this AC). The automatically selected display of powerplant information should not suppress other information that requires flightcrew awareness.
6.2.4.2 Powerplant information must be closely grouped (in accordance with § 25.1321) in an easily identifiable and logical arrangement that allows the flightcrew to clearly and quickly identify the displayed information and associate it with the corresponding engine. Typically, it is considered to be acceptable to arrange parameters related to one powerplant in a vertical manner and, according to powerplant position, next to the parameters related to another powerplant in such a way that identical powerplant parameters are horizontally aligned. Generally, place parameter indications in order of importance with the most important one at the top.
Typically, the top indication is the primary thrust setting parameter.
6.2.5 Arrangement—Other Information (For Example, Glideslope and Multi-Function Displays).
6.2.5.1 Glideslope or glidepath deviation scales should be located to the right side of the primary attitude indication. If glideslope deviation data is presented on both an electronic horizontal situation indicator and an electronic attitude direction indicator, the information should appear in the same relative location on each indicator.
6.2.5.2 When the glideslope pointer is being driven by an area navigation (RNAV) system with vertical navigation (VNAV) or instrument landing system (ILS) look-alike functionality, the pointer should not be marked “GS” or “glideslope.”
6.2.5.3 Navigation, weather, and vertical situation display information is often displayed on multi-function displays. This information may be displayed on one or more physical electronic displays, or on several areas of one 6-4
larger display. When this information is not required to be displayed continuously, it can be displayed part-time, but the displayed information should be easily recoverable to the flightcrew when needed. For guidance on part-time displays, see paragraph 6.3.3 of this chapter.
6.2.5.4 Other information should not be located where the primary flight information or required powerplant information is normally presented. See paragraphs 6.2.1 and 6.2.3 of this chapter for primary flight information guidance. See paragraphs 4.7 and 6.2.4 of this AC for powerplant information guidance.
6.3 Managing Display Information.
The following paragraphs address managing and integrating the display of information throughout the flight deck. This includes the use of windows to present information and the use of menus to manage the display of information.
6.3.1 Window.
A window is a defined area that can be present on one or more physical displays. A window that contains a set of related information is commonly referred to as a format.
Multiple windows may be presented on one physical display surface and may have different sizes. Guidelines for sharing information on a display, using separate windows, are as follows:
6.3.1.1 The window(s) should have fixed size(s) and location(s).
6.3.1.2 Separation between information elements within and across windows should be sufficient to allow the flightcrew to readily distinguish separate functions or functional groups (for example, powerplant indication) and avoid any distractions or unintended interaction.
6.3.1.3 Display of selectable information, such as a window on a display area, should not interfere with or affect the use of primary flight information.
6.3.1.4 For additional information regarding the display of data on a given location, data blending, and data over-writing, see Aeronautical Radio, Inc. (ARINC) Standard 661-5, Cockpit Display System Interfaces to User Systems.
6.3.2 Menu.
6.3.2.1 A menu is a displayed list of items from which the flightcrew can choose.
Menus include drop-down and scrolling menus, line select keys on a multi-function display, and flight management system menu trees. An option is one of the selectable items in a menu. Selection is the action a user makes in choosing a menu option, and it may be done by pointing 6-5
(with a cursor control device or other mechanism), entering an associated option code, or activating a function key.
6.3.2.2 The hierarchical structure and organization of the menus should be designed to allow the flightcrew to sequentially step through the available menus or options in a logical way that supports their tasks. The options provided on any particular menu should be logically related to each other.
Menus should be displayed in consistent locations, either a fixed location or a consistent relative location, so that the flightcrew knows where to find them. At all times the system should indicate the current position within the menu and menu hierarchy.
6.3.2.3 The number of sub-menus should be designed to assure timely access to the desired option without over-reliance on memorization of the menu structure. The presentation of items on the menu should allow clear distinction between items that select other menus and items that are the final selection.
6.3.2.4 The number of steps required to choose the desired option should be consistent with the frequency, importance, and urgency of the flightcrew’s task.
6.3.2.5 When a menu is displayed, it should not obscure required information.
6.3.3 Full-Time versus Part-Time Display of Information.
Some airplane parameters or status indications are required to be displayed by the regulations (for example, powerplant information required by § 25.1305), yet they may only be necessary or required in certain phases of flight. If it is desired to inhibit some parameters from full-time display, a usability level and functionality equivalent to a full-time display should be demonstrated.
6.3.3.1 When determining if information on a display can be part-time, consider the following criteria:
6.3.3.1.1 Continuous display of the parameter is not required for safety of flight in all normal flight phases.
6.3.3.1.2 The parameter is automatically displayed in flight phases where it is required, when its value indicates an abnormal condition, or when it would be relevant information during a failure condition.
6.3.3.1.3 Display of the inhibited parameter can be manually selected by the flightcrew without interfering with the display of other required information.
6.3.3.1.4 If the parameter fails to be displayed when required, the failure effect and compounding effects must meet the requirements of all applicable regulations (for example, § 25.1309).
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