U.S. Department of Transportation Federal Aviation Administration
Advisory Circular
Subject: ELECTRONIC FLIGHT DECK
DISPLAYS Date: 6/21/07 Initiated by: ANM-111 AC No: 25-11A
This advisory circular (AC) provides guidance for showing compliance with certain requirements of Title 14, Code of Federal Regulations (CFR), part 25, for the design, installation, integration, and approval of electronic flight deck displays, components, and systems installed in transport category airplanes.
Signed by Ali Bahrami
Ali Bahrami Manager, Transport Airplane Directorate Aircraft Certification Service
CONTENTS
Paragraph Page
CHAPTER 1. BACKGROUND
1. What is the Purpose of this Advisory Circular (AC)? 8
2. Who Does this AC Apply to? 8
3. Cancellation 8
4. General 8 Table 1 – Topics Within the Guidance of this AC 9 Table 2 – Topics Outside the Guidance of this AC 9
5. Definitions of Terms Used in this AC 11
6. Background 11
7. – 10. [RESERVED] 11
CHAPTER 2. ELECTRONIC DISPLAY SYSTEM OVERVIEW
11. General 12
a. Design Philosophy 12
b. Human Performance Considerations 12
c. Addressing Intended Function in the Certification Plan 13
12. – 15. [RESERVED] 13
CHAPTER 3. ELECTRONIC DISPLAY HARDWARE
16. Display Hardware Characteristics 14
a. Visual Display Characteristics 14
b. Installation 17
c. Power Bus Transient 19
17. – 20. [RESERVED] 20
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CHAPTER 4. SAFETY ASPECTS OF ELECTRONIC DISPLAY SYSTEMS
21. General 21
a. Identification of Failure Conditions 21
b. Effects of Display Failure Conditions 22
c. Mitigation of Failure Conditions 23
d. Validation of the Classification of Failure Conditions and Their Effects 24
e. System Safety Guidelines 25 Table 3 – Example Safety Objectives for Attitude Failure Conditions 27 Table 4 – Example Safety Objectives for Airspeed Failure Conditions 28 Table 5 – Example Safety Objectives for Barometric Altitude Failure Conditions 29 Table 6 – Example Safety Objectives for Heading Failure Conditions 30 Table 7 – Example Safety Objectives for Certain Navigation and Communication Failure Conditions 31 Table 8 – Example Safety Objectives for Failure Conditions of Other Parameters 32 Table 9 – Example Safety Objectives for Engine Failure Conditions 35 Table 10 – Failure Conditions for Display Systems Used as Controls 36
22. – 30. [RESERVED] 36
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Page
CHAPTER 5. ELECTRONIC DISPLAY INFORMATION ELEMENTS
AND FEATURES
31. Display Information Elements and Features 35
a. General 35
b. Consistency 36
c. Display Information Elements 36
(1) Text 36
(2) Labels 37
(3) Symbols 39
(4) Indications 40
(a) Numeric Readouts 40
(b) Scales, Dials, and Tapes 40
(c) Other Graphical Depictions 41
(5) Color Coding 42 Table 11 – Recommended Colors for Certain Functions 43 Table 12 – Specified Colors for Certain Display Features 43
d. Dynamic (Graphic) Information Elements on a Display 45
e. Sharing Information on a Display 45
(1) Overlays and Combined Information Elements 46
(2) Time Sharing 46
(3) Separating Information Visually 46
(4) Clutter and De-Clutter 47
f. Annunciations and Indications 47
(1) General 47
(2) Location 47
(3) Managing Messages and Prompts 47
(4) Blinking 48
g. Use of Imaging 48
32. – 35. [RESERVED] 49
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CHAPTER 6. ORGANIZING ELECTRONIC DISPLAY
INFORMATION ELEMENTS
36. Organizing Information Elements 50
a. General 50
b. Types and Arrangement of Display Information 50
(1) Placement - General Information 50
(2) Placement - Controls and Indications 51
(3) Arrangement - Basic T Information 51
(4) Arrangement - Powerplant Information 53
(5) Arrangement - Other Information (For Example, Glideslope and Multi-Function Displays) 53
c. Managing Display Information 54
(1) Window 54
(2) Menu 55
(3) Full-Time vs. Part-Time Display of Information 55
d. Managing Display Configuration 57
(1) Normal Conditions 57
(2) System Failure Conditions (Reconfiguration) 57
e. Methods of Reconfiguration 59
(1) Compacted Format 59
(2) Sensor Selection and Annunciation 60
37. – 40. [RESERVED] 60
CHAPTER 7. ELECTRONIC DISPLAY SYSTEM CONTROL DEVICES
41. General 61
a. Multi-function Control Labels 61
b. Multi-function Controls 61
(1) “Hard” Controls 61
(2) “Soft” Controls 62
c. Cursor Control Devices 63
d. Cursor Displays 64
42. – 45. [RESERVED] 64
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Page
CHAPTER 8. SHOWING COMPLIANCE FOR APPROVAL OF
ELECTRONIC DISPLAY SYSTEMS
46. Compliance Considerations (Test and Compliance) 65
a. General 65
b. Means of Compliance 65
47. – 50. [RESERVED] 67
CHAPTER 9. CONTINUED AIRWORTHINES AND MAINTENANCE
51. Continued Airworthiness and Maintenance 68
a. General 68
b. Design for Maintainability 68
c. Maintenance of Display Characteristics 69
52. – 60. [RESERVED] 69
Appendix Page
LIST OF APPENDICES
1 Primary Flight Information A1-1
1.1 Attitude A1-1
1.2 Continued Function of Primary Flight Information (Including Standby) in Conditions of Unusual Attitudes or in Rapid Maneuvers A1-1
2.1 Airspeed and Altitude A1-2
2.2 Airspeed and Altitude for HUD A1-3
2.3 Low and High Speed Awareness Cues A1-4
3. Vertical Speed A1-6
4. Flight Path Vector or Symbol A1-6
2 Powerplant Displays A2-1
1. General A2-1
2. Design Guidelines A2-2
3 Definitions A3-1 Figure A3-1 Primary Field of View A3-9 Figure A3-2 Display Format A3-11
4 Acronyms Used in This AC A4-1
5 Related Regulations and Documents A5-1 General A5-1
1. Regulations A5-1
2. Advisory Circulars A5-7
3. Technical Standard Orders A5-9
4. Other FAA Documents A5-13
5. ARAC Recommendations A5-13
6. JAA/EASA Documents A5-14
7. Industry Documents A5-14
a. ARINC A5-14
b. EUROCAE A5-15
c. ICAO A5-16
d. RTCA A5-16
e. SAE International (Formerly the Society of Automotive Engineers) A5-18
f. Other Document(s) A5-21
8 CHAPTER 1.
BACKGROUND
1. What is the purpose of this advisory circular (AC)? This AC provides guidance for showing compliance with certain requirements of Title 14, Code of Federal Regulations (CFR), part 25, as well as general guidance for the design, installation, integration, and approval of electronic flight deck displays, components, and systems installed in transport category airplanes.
2. Who does this AC apply to?
a. The guidance provided in this document is directed to airplane and avionics manufacturers, modifiers, and operators of transport category airplanes.
b. This material is neither mandatory nor regulatory in nature and does not constitute a regulation. It describes acceptable means, but not the only means, for demonstrating compliance with the applicable regulations. The Federal Aviation Administration (FAA) will consider other methods of demonstrating compliance that an applicant may elect to present. While these guidelines are not mandatory, they are derived from extensive FAA and industry experience in determining compliance with the relevant regulations. On the other hand, if we become aware of circumstances that convince us that following this AC would not result in compliance with the applicable regulations, we will not be bound by the terms of this AC, and we may require additional substantiation or design changes as a basis for finding compliance. Applicants for a technical standard order (TSO) should consider following the guidance in this AC when the TSO requirements do not provide sufficient guidance.
c. This material does not change, create any additional, authorize changes in, or permit deviations from, regulatory requirements.
3. Cancellation. This AC cancels AC 25-11, Transport Category Airplanes Electronic Display Systems, dated 16 July 1987.
4. General. This AC applies to the design, integration, installation, and certification approval of electronic flight deck displays, components, and systems for transport category airplanes. As a minimum this includes:
• General airworthiness considerations,
• Display system and component characteristics,
• Safety and criticality aspects,
• Functional characteristics,
• Display information characteristics,
• Guidance to manage display information,
• Flightcrew interface and interactivity, and
• Airworthiness approval (means of compliance) considerations.
Table 1, below, lists the topics within the guidance of this AC. Table 2, below, lists the topics not within the guidance of this AC.
Table 1 Topics Within the Guidance of This AC
Topics
Electronic pilot displays – including single function and multi-function displays.
Display features and functions that are intended for use by the pilot.
Display functions not intended for use by the pilot if they may interfere with the pilot’s flying duties.
Display aspects of Class III Electronic Flight Bag (installed equipment).
Controls associated with the electronic displays covered in this AC. These controls include hard controls (physical buttons and knobs) and soft controls (virtual or programmable buttons and knobs, generally controlled through a cursor device or line select keys).
Electronic standby displays.
Head Up Displays (HUD).
Enhanced and Synthetic Vision Systems.
Table 2 Topics Outside the Guidance of This AC
Topics
Display functions not intended for use by the pilot.
In flight entertainment displays.
Flight attendant displays.
Maintenance terminals, even if they are in the flight deck, but not intended for use by the pilots.
Head mounted displays used by pilots.
Displays in the flightcrew rest area.
Handheld or laptop items (not installed equipment).
Class I and Class II Electronic Flight Bags.
Electromechanical instruments.
Auditory “displays” (for example, aural alerts), and tactile “displays” (for example, stick shaker).
Flight controls, throttles, and other (hard) controls not directly associated with the electronic displays.
a. Other advisory material is available for use in establishing guidance for specific functionality and characteristics provided by electronic displays. For example, AC 25-23, Airworthiness Criteria for the Installation Approval of a Terrain Awareness and Warning System (TAWS) for Part 25 Airplanes, describes a means for airworthiness approval of TAWS, and includes guidance on the display of TAWS. This revised AC 25-11A is not intended to replace or conflict with any existing AC. Its purpose is to provide general, highlevel guidance for electronic displays in the flight deck. Conflicts between this AC and other advisory material, if any, will be resolved on a case-by-case basis, in agreement with the FAA. In those cases, the more specifically applicable material should control.
b. The combination of the guidance material in this AC, the Aviation Rulemaking Advisory Committee (ARAC) recommendations for adding a new regulation to 14 CFR part 25 and revising two existing part 25 regulations, and the associated guidance material for the ARAC recommendations, is intended to represent the design characteristics and techniques that are:
• widely accepted in the aviation industry,
• relevant to the regulatory requirements, and
• can be reasonably applied to transport airplane certification programs for electronic flight deck displays.
c. The ARAC recommendations include adding a new § 25.1302, Installed Systems and Equipment for Use by the Flight Crew and revising the existing § 25.1309, Equipment, Systems, and Installation; § 25.1322, Flightcrew Alerting; and § 25.1333(b), Instrument systems. It is the FAA’s intent that the information in this AC 25-11A does not duplicate or conflict with the information provided in the guidance material that will possibly be created as a result of the ARAC recommendations for § 25.1302, § 25.1309, § 25.1322, and § 25.1333(b).
(1) For information about the ARAC recommendation for § 25.1302 go to http://www.faa.gov/regulations_policies/rulemaking/committees/arac/media/tae/TAE_ HFH_T1.pdf.
(2) For information about the ARAC recommendation for § 25.1309 go to http://www.faa.gov/regulations_policies/rulemaking/committees/arac/media/tae/TAE_S DA_T2.pdf.
(3) For information about the ARAC recommendation for § 25.1322 go to http://www.faa.gov/regulations_policies/rulemaking/committees/arac/media/tae/ TAE_ASH_T4.pdf.
(4) For information about the ARAC recommendation for § 25.1333(b) go to http://www.faa.gov/regulations_policies/rulemaking/committees/arac/ issue_areas/tae/asm/. Section 25.1333(b) is part of the recommendations for “Task 2 - Cockpit Instrument Systems.”
5. Definitions of Terms Used in this AC.
a. For the purposes of this AC, a “display system” includes not only the display hardware and software components but the entire set of avionic devices implemented to display information to the flightcrew. Hardware and software components of other systems that affect displays, display functions, or display controls should take into account the display aspects of this AC. For example, this AC would be applicable to a display used when setting the barometric correction for the altimeter, even though the barometric set function may be part of another system.
b. For the purposes of this AC, “foreseeable conditions” means the full environment in which the display or the display system is assumed to operate, given its intended function.
This includes operating in normal, non-normal, and emergency conditions.
c. Definitions of technical terms used in this AC can be found in Appendix 3 of this AC.
The acronyms used throughout this document are included in Appendix 4 of this AC. A list of applicable regulations, related guidance, and industry material is included in Appendix 5 of this AC.
6. Background.
a. Electronic displays can present unique opportunities and challenges to the design and certification process. In many cases, showing compliance with regulatory requirements related to the latest flight deck display system capabilities has been subject to a great deal of interpretation by applicants and the FAA. At the time the first electronic displays were developed, they were direct replacements for the conventional electromechanical components. The initial release of AC 25-11 established guidance for the approval of cathode ray tube (CRT) based electronic display systems used for guidance, control, or decision-making by the flightcrews of transport category airplanes. This initial guidance was appropriate for CRTs, but additional guidance was needed to update AC 25-11 to address new technologies.
b. The FAA and European Aviation Safety Agency (EASA) have established a number of regulatory requirements intended to improve aviation safety by requiring that the flight deck design have certain capabilities and characteristics. The approval of flight deck displays and display systems has typically been addressed by invoking many rules that are specific to
12 certain systems, or to rules with general applicability such as §§ 25.1301(a), 25.771(a), and
25.1523. Thus, this AC provides guidance related to these and other applicable regulations.
7. - 10. [RESERVED]