CONTENTS
Paragraph Page
Chapter 1. Background
11. General 13
a. Advisory Circular (AC) 25.1329-1A 13
b. Scope 13
12. Evolution of Flight Guidance Systems (FGS) 13
a. Complexity 13
b. Guidance Considerations 13 13 – 16. [RESERVED] 13
Chapter 2. Overview of Flight Guidance Systems (FGS)
17. Purpose of FGS 15
18. FGS Components 15
a. Included in Definition 15
b. Excluded from Definition 15
19. FGS Functions 15
a. Elements of FGS 15
b. Approach and Landing System 15
c. Flight Management System (FMS) 16
d. Design Philosophy 16
e. Description of FGS Behavior and Operation 16
20. Compliance with § 25.1329 16
a. General 16
b. Relevant Paragraphs 16 Table 2-1 Cross-References § 25.1329 Paragraphs to AC Chapters 17 21 – 26 [RESERVED] 22
Chapter 3. FGS Engagement, Disengagement, Indications, and Override
27. Autopilot Engagement, Disengagement, and Indications 23
a. Autopilot Engagement 23
(1) Single Switch Action 23
(2) Engagement Status of Autopilot 23
(3) Multiple Autopilots 23
(4) Acceptable Transients 23 1
Paragraph Page
(5) Flight Director (FD) Not Engaged 23
(6) FD Engaged 24
b. Autopilot Disengagement 24
(1) General 24
(2) Autopilot Disengagement Alerts 25
(3) Quick Disengagement Control 26
(4) Alternative Means of Autopilot Disengagement 26
(5) Flightcrew Pitch Trim Input 27
28. FD Engagement, Disengagement, and Indications 27
a. FD Engagement 27
(1) General 27
(2) Guidance Cue(s) 28
(3) Reactive Windshear Guidance System 28
b. FD Disengagement 29
29. Autothrust Engagement, Disengagement, and Indications 29
a. Autothrust Engagement 29
(1) Indication 29
(2) Accessibility of Controls 29
(3) Inadvertent Engagement/Disengagement 29
(4) Automatic Engagement 29
b. Autothrust Disengagement 30
(1) Indication of Disengagement 30
(2) Inadvertent Disengagement 30
(3) Consequence of Disengagement 30
(4) Autothrust Quick Disengagement Control 30
30. Override of the FGS 31
a. General 31
b. Autopilot Override 31
(1) With Automatic Disengagement 31
(2) Without Automatic Disengagement 31
c. Autothrust Override 32
(1) Force Required 32
(2) Response to Override 32
(3) Engagement Status with Override 32
31. FGS Engagement Mode Compatibility 33
a. FGS Mode Engagement Philosophy 33
b. Engagement Mode Compatibility 33 32 — 41. [RESERVED] 33
Chapter 4. Controls, Indications, and Alerts
Paragraph Page
42. General 35
a. Human-Machine Interface 35
b. Design of Controls, Indications, and Alerts 35
c. Evaluation of Information Provided by FGS 35
43. FGS Controls 35
a. General 35
b. Design Considerations 35
(1) Differentiation of Knob Shape and Position 35
(2) Design to Support Correct Selection of Target Values 36
(3) Commonality Across Aircraft Types 36
(4) Positioning of Controls and Related Indications 36
(5) Inadvertent Operation 36
44. FGS Mode Selection, Annunciation, and Indication 36
a. Annunciation of Engagement of the FGS 36
b. Description of FGS Modes 36
c. FGS Mode Annunciations 36
(1) Active and Armed Modes 36
(2) Location 37
(3) Discriminators 37
(4) Color 37
d. Mode Changes 37
(1) Operationally Relevant Mode Changes 37
(2) Attention-Getting Features 37
(3) Use of Alerts 38
e. Failure to Engage or Arm 38
f. FGS Mode Display and Indications 38
45. FGS Alerting, Warning, Caution, Advisory, and Status 38
a. General 38
(1) Alerting Provisions 38
(2) Determination of FGS Capability 38
b. Speed Protection Alerts 38
(1) Alerts to Crew 38
(2) Alert Specifications 39
(3) Consistency 39
(4) Nuisance Alerts 39
c. Loss of Autopilot Approach Mode 39
d. Awareness of Potential Significant Transient Condition (“Bark Before Bite”) 39
(1) General 39
(2) Flightcrew Alert(s) 39
(3) Situations to Consider for an Alert 40 3
Paragraph Page
(4) Automatic Disengagement 40
46. FGS Considerations for Head Up Displays (HUD) 41
a. General 41
b. Characteristics of HUD Guidance 41
(1) Supplemental Use Display System 41
(2) External Visual References 41
(3) Interference and Occlusion 41
(4) Display Criteria 42
(5) Conformal Symbology 42
(6) Low Visibility Approach 42
(7) Clutter 42
c. HUD/Head Down Display (HDD) Compatibility 42
(1) General 42
(2) Consistency and Compatibility 42
d. Alerting Issues 43
(1) Alerts Displayed on HUDs 43
(2) Monochrome HUDs 44
(3) Mulit-Color HUDs 44
(4) Single HUD Installation 44
(5) Dual HUD Installations 44
(6) Ground Proximity Warning System (GPWS)/Traffic Alert and Collision Avoidance System (TCAS) Alerts On HUD 44
e. Upset/Unusual Attitude Recovery Guidance 44
(1) Guidance Cues 44
(2) Orientation Cues 45 47 – 51. [RESERVED] 45
Chapter 5. Performance of Function
52. General 47
a. Intended Function 47
b. Effect of System Tolerances 47
53. Normal Performance 47
a. General 47
b. Conditions to Consider 47 Table 5.1 Examples of Normal Conditions 48
c. Level of Performance 49
(1) Significant Characteristics 49
(2) Configuration Changes 49
(3) Compliance Evaluation 49
(4) Prescribed Levels of Performance 49
(5) Equivalence of Performance 49
(6) Autopilot 49 4
Paragraph Page
(7) Flight Director (FD) 49
(8) Autothrust 49
(9) Automatic Trim 49
54. Performance in Rare Normal Conditions 50
a. General 50
(1) Range of Conditions 50
(2) Effect on Performance 50
b. Conditions to Consider 50 Table 5-2 Examples of Rare Normal Conditions 51
c. Level of Performance 52
(1) Performance Standard 52
(2) Autopilot Authority Limit 52
(3) Masking of Potential Hazard 52
55. Icing Considerations in Normal and Rare Normal Conditions 52
a. Effect on Performance 52
b. Alerts 52
c. Effect on Speed Protection 53
56. Performance in Non-Normal Conditions 53
a. General 53
b. Considerations to Consider 53 Table 5-3 Examples of Non-Normal Conditions 54
c. Level of Performance 55
(1) Performance Standard 55
(2) Autopilot Authority Limit 55
(3) Masking of Potential Hazard 55
57. Speed Protection 55
a. General 55
(1) Speed Excursions 55
(2) Compliance with § 25.1329(h) 55
(3) Design Standard 56
b. Low Speed Protection 57
(1) General 57
(2) Factors to Consider 57
(3) Low Speed Protection During Approach Operations 57
(4) Windshear Recovery Guidance 59
c. High Speed Protection 59
(1) General 59
(2) Factors to Consider 59 58 – 61. [RESERVED] 60
Chapter 6. Characteristics of Specific Modes
Paragraph Page
62. General 61
63. Lateral Modes 61
a. Heading or Track Hold 61
b. Heading or Track Select 61
c. Lateral Navigation (LNAV) Mode 61
(1) Lateral Flight Path 61
(2) Automatic Mode Transitions 61
(3) Takeoff or Go-Around (TOGA) 62
64. Vertical Modes 62
a. Target Altitude Selection 62
b. Vertical Speed 62
c. Flight Path Angle 62
d. Indicated Airspeed (IAS)/Mach Hold [speed on elevator] 62
e. Indicated Airspeed (IAS)/Mach Select [speed on elevator] 62
f. Flight Level (FL) Change [speed on elevator] 63
g. Altitude Capture 63
(1) Mode Transition 63
(2) Guidelines for Altitude Capture Mode 63
h. Altitude Hold 64
(1) Entering Mode 64
(2) Mode Transition Annunciation 64
(3) Barometric Pressure Adjustment 64
i. VNAV 65
(1) FMS Path 65
(2) Climb or Descent 65
65. Multi-Axis Modes 66
a. Takeoff Mode 66
(1) Vertical Guidance 66
(2) Lateral Guidance 66
(3) Rotation Guidance 66
(4) Autothrust 66
(5) Operation and Performance 66
b. Go-Around Mode 67
(1) Vertical Elements 67
(2) Speed 67
(3) Autothrust 67
(4) Engagement 68
(5) All Engine and Engine Out Capability 68
c. Approach Mode 68
(1) Final Approach Path 68
(2) Mode Annunciations 68 6
Paragraph Page
(3) Sub-Modes 68
(4) Mode Engagement Sequence 68
66. Autothrust Modes 68
a. Thrust Mode 68
b. Speed Mode 68
c. Retard Mode 69
67. Special Considerations for VNAV Approach Operations Related to Selecting a Target Altitude 69
a. Approach Operations 69
b. VNAV Path Operations 69
68. Control Wheel Steering (CWS) [control steering through the autopilot] 69
a. General 69
b. Design 69
(1) Control Forces 69
(2) Bank and Pitch Attitudes 70
(3) Control Behavior 70
(4) Stall and Stall Recovery 70
(5) Adjustments to Trim 70
(6) Takeoff and Landing 70
(7) Automatic Reversion to CWS Mode 70
c. Terminology 71
(1) Touch Control Steering (TCS) 71
(2) Supervisory Override 71
69. Special Considerations for the Integration of Fly-by-Wire Flight Control Systems and FGS 71
a. Speed Protection 71
b. System Degradation 71 70 – 74 [RESERVED] 71
Chapter 7. FGS Integration
75. General 73
76. System Integration Issues 73
a. Common and Cascading Failure Modes 73
b. Risk of Error 73
c. System Safety Analysis 73
77. Functional Interfaces 74
a. Interfacing Sensors 74
b. Potential Inconsistencies Between Systems 74
c. Function and Performance 74 78 – 82 [RESERVED] 74
Chapter 8. Safety Assessment
Paragraph Page
83. General 75
a. Basic Safety Requirements 75
b. Safety Assessment 75
c. Validation of Safety Assessment 75
d. Coordination with the FAA 75
84. FGS Failure Conditions 75
a. Functionality 76
b. Effect of Failure Condition 76
85. Type and Severity of Failure Conditions 76
a. Types of Failure Conditions 76
(1) Loss of Function 76
(2) Malfunction 77
b. Cause 77
c. Severity 77
d. Assessment of Failure Conditions 77
(1) Functional Failures 77
(2) Airframe Loads 77
(3) Assessing Total Effect of Failure 78
86. Mitigation of Failure Conditions 78
a. General 78
b. Identification of Methods 78
c. FGS De-Selection 78
87. Validation of Failure Conditions 78
a. General 78
b. Validation Options 79
c. Validation Methodology 79
88. Specific Considerations 79
a. FGS Action During Ground Operations 79
b. FGS Operations in Close Proximity to the Ground 79
(1) Takeoff 80
(2) Approach 81
c. Cruise Operations 82
d. Asymmetric Thrust During Autothrust Operation 82
89. Failure to Disengage the FGS 83 90 – 97 [RESERVED] 83
Chapter 9. Compliance Demon stration Using Flight Test and Simulation
Paragraph Page
98. General 85
a. Methods of Compliance Demonstration 85
b. Criteria for Establishing Compliance 85
c. Elements of Certification Flight Test 85
d. Pilot–in–the–Loop Evaluation 85
e. Other Applicable Guidance Material for FGS Takeoff and/or Approach Modes 86
(1) Criteria to Consider 86
(2) Procedures to Show Compliance 86
f. Relation of AC Chapters 86 Figure 9-1, Relationship Between AC Chapters 87
99. Performance Demonstration (Fault Free): § 25.1301 88
a. General 88
(1) Certification Plan 88
(2) Evaluating Performance 88
(3) Evaluating Compatibility of Mode Controls, Indications, and Alerts 88
b. Normal Performance 88
(1) Demonstration 88
(2) Evaluation 88
(3) Expected Errors 89
c. Performance in “Other Than Normal” Conditions 89
(1) Test Program 89
(2) Evaluation of FGS 89
(3) Additional Guidance for Windshear 89
d. Specific Performance Conditions 89
(1) Icing Considerations 89
(2) Low-Speed Protection 90
(3) High-Speed Protection 91
(4) Go-Around 91
(5) Steep Approach [special authorization] 92
(6) Indication Of and Response To an Out Of Trim Condition 93
e. Flight Director (FD) /Head Up Display (HUD 93
(1) General 93
(2) Specific Demonstrations for HUD 94
(3) Simulator Demonstration for HUD 95
f. Flightcrew Override of the FGS 96
(1) Autopilot Override 96
(2) Autothrust Override 97
(3) Pitch Trim System Evaluation During Autopilot Override 97 9
10 Paragraph Page
100. Failure Conditions Requiring Validation: § 25.1309 97
a. General 97
(1) Safety Assessment 97
(2) Evaluation of Failure Conditions 97
b. Validation Elements 98
(1) Assessment 98
(2) Failure Condition 98
(3) Pilot Recognition 98
(4) Pilot Reaction Time 100
(5) Pilot Recovery 100
c. Takeoff 101
(1) Worst Case Failure Condition 101
(2) Failures to be Evaluated 101
(3) On Runway Guidance 101
d. Climb, Cruise, Descent, and Holding 101
e. Maneuvering 101
f. Approach 101
(1) Approach With Vertical Path Reference 101
(2) Approach Without Vertical Path Reference 103
(3) Steep Approach 103
g. Specific Conditions 103
(1) Failure Conditions to be Evaluated 103
(2) Failure to Disengage 103
101. Criteria Supporting Operational Use of Autopilot 103
a. Typical Flight Operations 103
b. Operations in Close Proximity to the Ground 104
(1) General 104
(2) Considerations 104
(3) Autopilot Engagement Altitude/Height After Takeoff 104
(4) Autopilot Engagement During Approach 105
(5) Circling Approach 107
c. Climb, Cruise, Descent, and Holding 107
d. Maneuvering 107
102. Automatic Disengagement of the Autopilot 108
103. Assessment of Human Factors 108
a. General 108
b. Flight Evaluations 108
(1) During Certification 108
(2) Prior to Certification 108
(3) Credit to Establish FGS Compliance 109
(4) Simulation Versus Flight Tests 109
c. Structured Subjective Evaluations 109
d. Pilot Training and Experience 110
Change 1
Paragraph Page
e. Evaluating New or Unique Design Features 110
f. Certification Planning Documentation 110 104 – 108 [RESERVED] 110
Chapter 10. Airplane Flight Manual
109. General 111
a. AFM Terminology 111
b. Low-Visibility Operations 111
110. Information Supporting Operational Use of Autopilot 111
a. General 111
b. Specifying a Minimum Use Height (MUH) 111
(1) Takeoff 111
(2) Cruise 111
(3) Approach 111
c. Maximum Displacement Deviation 112
111. Limitations 112
112. Non-Normal/Emergency Procedures 112
113. Normal Procedures 112
a. Documentation of Normal Procedures 112
b. Maximum Displacement Deviation 112
c. Procedures for Use of FGS in Icing Conditions 112
d. Aircraft With Published Flightcrew Operation Manuals (FCOM) 112
e. Aircraft Without Published FCOMs 113
Appendices
1 Safety Assessment A1-1
1. General A1-1
2. Identification of Failure Conditions A1-1
3. Considerations When Assessing The Severity of Failure Condition Effects A1-2
4. Failure Condition Classification A1-3 2 Definitions A2-1 3 Acronyms A3-1
Change 1
Tables
Number Page 2-1 Cross-References § 25.1329 Paragraphs to AC Chapters 17 5-1 Examples of Normal Conditions 48 5-2 Examples of Rare Normal Conditions 51 5-3 Examples of Non-Normal Conditions 54
Figures
Number Page 9-1 Relationship Between AC Chapters (Chapter 9) 87