AC 25-11B

U.S. Department Advisor of Transportation Federal Aviation Administration Circular Subject: Electronic Flight Displays Date: 10/07/14 AC No: 25-11B Initiated By: ANM-111 This advisory circular (AC) provides guidance for showing compliance with certain requirements of Title 14, Code of Federal Regulations part 25 for the design, installation, integration, and approval of electronic flight deck displays, components, and systems installed in transport category airplanes. Revision B adds appendices F and G to the original AC and updates references to related rules and documents.

If you have suggestions for improving this AC, you may use the Advisory Circular Feedback form at the end of this AC.

Jeffrey E. Duven Manager, Transport Airplane Directorate Aircraft Certification Service

10/ 07/14 AC 25-11B

CONTENTS

Paragraph Page

Chapter 1. Introduction1-1

1.1 Purpose1-1

1.2 Applicability.1-1

1.3 Cancelation.1-1

1.4 General1-1

1.5 Definitions of Terms Used in this AC.1-4

1.6 Background1-4

Chapter 2. Electronic Display System Overview2-1

2.1 General2-1

2.2 Design Philosophy.2-1

2.3 Human Performance Considerations2-2

2.4 Addressing I ntended Function in the Certification Plan2-2

2.5 Non-Interference with Flying Duties2-2

Chapter 3. Electronic Display Hardware3-1

3.1 Display Hardware Characteristics3-1

3.2 Visual Display Characteristics3-1

3.3 Installation3-4

3.4 Power Bus Transient3-6

Chapter 4. Safety Aspects of Electronic Display Systems4-1

4.1 General4-1

4.2 Identification of Failure Conditions4-1

4.3 Effects of Display Failure Conditions4-2

4.4 Mitigation of Failure Conditions.4-3

4.5 Validation of the Classification of Failure Conditions and Their Effects.4-4

4.6 System Safety Guidelines.4-4

4.7 System Safety Assessment Guidelines.4-6

Chapter 5. Electronic Display Information Elements and Features5-1

5.1 Display Information Elements and Features5-1

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CONTENTS (CONTINUED)

Paragraph Page

5.2 General5-1

5.3 Consistency5-2

5.4 Display Information Elements.5-3

5.5 Labels5-3

5.6 Symbols5-5

5.7 Indications5-6

5.8 Color Coding5-7

5.9 Dynamic (Graphic) Information Elements on a Display.5-11

5.10 Sharing I nformation on a Display5-12

5.11 Annunciations and Indications5-13

Chapter 6. Organizing Electronic Display Information Elements6-1

6.1 Organizing Information Elements6-1

6.2 Types and Arrangement of Display I nformation6-1

6.3 Managing Display Information6-5

6.4 Managing Display Configuration6-8

6.5 Methods of Reconfiguration6-10

Chapter 7. Electronic Display System Control Devices7-1

7.1 General7-1

7.2 Multi-Function Control Labels.7-1

7.3 Multi-Function Controls7-1

7.4 Cursor Control Devices7-3

7.5 Cursor Displays7-4

Chapter 8. Showing Compliance for Approval of Electronic Display Systems8-1

8.1 General Compliance Considerations (Test and Compliance)8-1

8.2 Means of Compliance.8-1

Chapter 9. Continued Airworthiness and Maintenance9-1

9.1 Continued Airworthiness and Maintenance9-1

9.2 General9-1

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CONTENTS (CONTINUED)

Paragraph Page

9.3 Design for Maintainability9-1

9.4 Maintenance of Display Characteristics.9-2

Appendix A. Primary Flight InformationA-1

A.1 GeneralA-1

A.2 Attitude.A-1

A.3 Continued Function of Primary Flight Information (Including Standby) in

Conditions of Unusual Attitudes or in Rapid ManeuversA-1

A.4 Airspeed and AltitudeA-2

A.5 Low- and High-Airspeed Awareness CuesA-3

A.6 Vertical SpeedA-5

A.7 Flight Path Vector or Symbol.A-5

Appendix B. Powerplant DisplaysB-1

B.1 GeneralB-1

B.2 Design GuidelinesB-2

Appendix C. DefinitionsC-1

Appendix D. AcronymsD-1

Appendix E. Related Regulations and DocumentsE-1

E.1 GeneralE-1

E.2 Regulations.E-1

E.3 Advisory CircularsE-6

E.4 Technical Standard OrdersE-8

E.5 Other FAA Documents.E-11

E.6 ARAC RecommendationsE-12

E.7 JAA/EASA Documents.E-12

E.8 Industry DocumentsE-12

E.9 Other DocumentsE-18

Appendix F. Head-Up Displays (HUDs)F-1

F.1 IntroductionF-1

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CONTENTS (CONTINUED)

Paragraph Page

F.2 Unique Safety ConsiderationsF-2

F.3 Design.F-3

F.4 HUD Design Eyebox CriteriaF-6

F.5 Guidelines for Presenting InformationF-10

F.6 Dual HUDsF-16

F.7 Flight Data RecordingF-18

F.8 Continued AirworthinessF-18

Appendix G. Weather Displays.G-1

G.1 IntroductionG-1

G.2 Key Characteristics.G-1

G.3 On-Board Weather Radar Information.G-4

G.4 Predictive Windshear InformationG-4

G.5 Safety AspectsG-5

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CONTENTS (CONTINUED)

TABLES

Number Page

Table 1-1. Topics Within the Guidance of this AC1-2

Table 1-2. Topics Outside the Guidance of this AC1-3

Table 4-1. Example Safety Objectives for Attitude Failure Conditions4-7

Table 4-2. Example Safety Objectives for Airspeed Failure Conditions4-8

Table 4-3. Example Safety Objectives for Barometric Altitude Failure Conditions4-9

Table 4-4. Example of Safety Objectives for Heading Failure Conditions4-10

Table 4-5. Example Safety Objectives for Certain Navigation and Communication

Failure Conditions4-11

Table 4-6. Example Safety Objectives for Failure Conditions of Other Parameters4-12

Table 4-7. Example Safety Objectives for Engine Failure Conditions4-14

Table 4-8. Failure Conditions for Display Systems Used as Controls4-14

Table 5-1. Recommended Colors for Certain Functions5-9

Table 5-2. Specified Colors for Certain Display Features5-10

Table E-1. RegulationsE-1

Table E-2. Advisory CircularsE-6

Table E-3. TSOs That May Be Applicable to Electronic DisplaysE-9

Table E-4. EASA/JAA DocumentsE-12

Table E-5. EUROCAE DocumentsE-13

Table E-6. RTCA DocumentsE-14

Table E-7. SAE International Documents.E-16

Table F-1. Display Error TolerancesF-8

Table F-2. Symbol Guidelines for HUD-HDD CompatibilityF-11

FIGURES

Figure C-1. Display FormatC-6

Figure C-2. Primary Field-of-ViewC-11

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CHAPTER 1. INTRODUCTION

1.1 Purpose.

This advisory circular (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.

Appendix A of this AC provides additional guidance for displaying primary flight information (required by §§ 25.1303(b) and 25.1333(b)), and appendix B of this AC provides additional guidance for powerplant displays.

1.2 Applicability.

1.2.1 The guidance provided in this AC is directed to airplane and avionics manufacturers, modifiers, and operators of transport category airplanes.

1.2.2 This material in this AC is neither mandatory nor regulatory in nature and does not constitute a regulation. It describes acceptable means, but not the only means, for showing compliance with the applicable regulations. The Federal Aviation Administration (FAA) will consider other methods of showing 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. If, however, 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.

1.2.3 This material in this AC does not change or create any additional regulatory requirements, nor does it authorize changes in, or permit deviations from, regulatory requirements.

1.3 Cancellation.

This AC cancels AC 25-11A, Electronic Flight Display Systems, dated June 21, 2007.

1.4 General.

1.4.1 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, 1-1

• 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.

.4.2 Table 1-1 lists the topics within the guidance of this AC. Table 1-2 lists the topics within the guidance of this AC.

Table 1-1. Topics Within the Guidance of this AC 1 not 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 (HUDs).

Enhanced and synthetic vision systems.

1-2

Table 1-2. 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.

1.4.3 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 25-11B is not intended to replace or conflict with any existing AC. Its purpose is to provide general, high-level 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 be followed.

1.4.4 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— 1-3

• 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.

1.4.5 The ARAC recommendations include revising the existing § 25.1309, Equipment, systems, and installations; and § 25.1333(b), Instrument systems. It is the FAA’s intent that the information in this AC 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 §§ 25.1309 and 25.1333(b).

1.4.5.1 For information about the ARAC recommendation for § 25.1309, see ARAC Task 2 - System Design and Analysis Harmonization and Technology Update at the FAA website.

1.4.5.2 For information about the ARAC recommendation for § 25.1333(b), see ARAC Task 2 - Cockpit Instrument System at the FAA website.

Section 25.1333(b) is one part of the recommendations for this task.

1.5 Definitions of Terms Used in this AC.

1.5.1 For the purposes of this AC, a “display system” includes no and software components but also the entire set of avionic d display information to the flightcrew. Hardware and softwa t only the display hardware evices implemented to re 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.

1.5.2 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.

1.5.3 Definitions of technical terms used in this AC can be found in appendix C of this AC.

The acronyms used throughout this document are included in appendix D of this AC. A list of applicable regulations, related guidance, and industry material is included in appendix E of this AC.

1.6 Background.

1.6.1 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 1-4

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. Additional appendices have been added as new types of displays have been developed. Appendix F includes guidance for HUDs, and appendix G includes guidance for weather displays.

1.6.2 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 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.

1-5

CHAPTER 2. ELECTRONIC DISPLAY SYSTEM OVERVIEW

2.1 General.

The following paragraphs provide guidance that applies to the overall electronic display system. This chapter, together with chapters 1 through 7 of this AC, provides compliance objectives and design guidance. Chapter 8 provides general guidance on how to show compliance for approval of electronic display systems. The material in chapters 2 through 9 and appendices A and B of this AC constitutes an overall method of compliance for the approval of an electronic display system.

2.2 Design Philosophy.

The applicant should establish, document, and follow a design philosophy for the display system that supports the intended functions (§ 25.1301). The documented design philosophy may be included as part of a system description, certification plan, or other document that is submitted to the FAA during a certification project. The design philosophy should include a high level description of (1) information presentation,

(2) color of electronic displays, (3) information management, (4) interactivity, and

(5) redundancy management.

2.2.1 General Philosophy of Information Presentation.

For example, is a “quiet, dark” flight deck philosophy used or is some other approach used?

2.2.2 Color Philosophy on the Electronic Displays.

The meaning and intended interpretation of different colors. For example, does magenta always represent a constraint?

2.2.3 Information Management Philosophy.

For example, when should the pilot take an action to retrieve information or is it brought up automatically? What is the intended interpretation of the location of the information?

2.2.4 Interactivity Philosophy.

For example, when and why is pilot confirmation of actions requested? When is feedback provided?

2.2.5 Redundancy Management Philosophy.

For example, how are single and multiple display failures accommodated? How are power supply and data bus failures accommodated?

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