Appendix A SECTION 5 - PERFORMANCE No Change SECTION 6 - WEIGHT AND BALANCE <Refer to revised weight and balance data, if applicable.> SECTION 7 - SYSTEM DESCRIPTION <Provide a brief description of the system, its operation, installation, etc.> FAA Approved Page <> of <> Date: ________ A-5
Appendix B APPENDIX B. SYNTHETIC VISION SYSTEMS INSTALLED IN ROTORCRAFT B.1 General.
This appendix provides guidelines for the installation of SVS in rotorcraft as nonrequired safety enhancing equipment. To promote standardized installation of nonrequired safety enhancing equipment, a policy memorandum, PS-ASW-27, 29-10, Policy Statement Concerning Non-Required Safety Enhancing Equipment (NORSEE) in Rotorcraft, dated 5/29/2013, was published to address a means of compliance for the installation of non-required safety enhancing equipment. Contact your ACO for guidance. Also, refer to AC 27-1B and AC 29-2C for certification guidance.
B.2 Applicability.
There are unique aspects to rotorcraft that do not apply to fixed wing aircraft. Rotorcraft typically operate at altitudes much closer to the ground and obstacles than fixed-wing aircraft. Additionally, they are inherently unstable and, without a stabilization system, require hands-on control at all times accompanied by constant visual scans to keep the rotorcraft oriented correctly. There are advantages and disadvantages to presenting SVS information to the pilot. Particular issues of concern are the compelling nature of the display used in a VFR see-and-avoid environment, the presentation of misleading information relating to aircraft location relative to hazards (particularly in night operations), and the installation of SVS displays that interact with automated flight control systems and flight guidance systems.
B.3 Airworthiness Approval.
For rotorcraft, the applicant should accomplish all SVS/SVGS/ASA-SVS installations on the primary flight display (PFD) or navigation display through the TC/STC/ATC process.
B.4 Design Considerations.
The functional hazard analysis (FHA) developed for the system should define the hazards of presenting misleading information to the pilot, and loss of an SVS feature.
The system should be designed accordingly. The hazard classification will be based on display location, intended function of the system features, and phase of flight. The hazard classification of misleading information for SVS on the primary flight displays will be higher than the classification of misleading information on a display outside the pilot’s primary field of view. For example, the hazard classification of misleading information may be lower if the SVS is placed on ancillary displays not used for the display of flight information and not in the pilot’s primary field of view. The intended function of the SVS/SVGS/ASA-SVS should be defined as it specifically applies for the rotorcraft application. If HTAWS or HTAWS-like features are incorporated, see TSO- C194 HTAWS, AC 27-1B, or AC 29-2C, MG-18 as appropriate for additional criteria.
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Appendix C APPENDIX C. ADDITIONAL CONSIDERATIONS FOR SYNTHETIC VISION SYSTEM
USED FOR SITUATION AWARENESS ONLY C.1 Terrain Alerting.
Any airplane equipment incorporating a synthetic vision system should also provide some type of terrain warning for pilots. The terrain warning feature should be incorporated on the Multifunction Display (MFD) or separate display unless the applicant can demonstrate that the feature is effective on the PFD. Synthetic vision systems on the PFD should provide adequate altitude and distance cues if used for terrain warning.
Applicants may use TSO-C151d, TAWS, Class A, B, or C, or TSO-C194 standards as applicable. Applicants may develop their own terrain warning system. However, the option of developing a terrain warning system is only available when there is not a specific carriage requirement for TAWS or HTAWS; it is not a substitute for any TAWS or HTAWS regulatory requirement. Applicants who want to develop their own terrain warning system should include:
x A one-minute caution and 30-second warning if the airplane’s current flight path will collide with terrain.
x A 20 second caution and 10 second warning if the rotorcraft’s current flight path will collide with terrain.
x Aural call-out for both the caution and the warning (CAUTION – TERRAIN, TERRAIN; WARNING – TERRAIN, TERRAIN).
x Terrain impact region highlighted on the moving map.
x A safety margin or buffer of at least 100 feet for cumulative errors in both the GPS altitude and terrain database.
x A terrain database/digital evaluation model (DEM) developed using the criteria in RTCA DO-200B, Standards for Processing Aeronautical Data, dated June 18, 2015.
x The synthetic vision display must not provide any information that is in conflict with or incompatible with either the terrain warning or terrain awareness functions of the TAWS or HTAWS.
C.2 Moving Map Display that Corresponds to and Complements Synthetic Vision PFD Display.
If there is a second complementary map view display, the second display should depict the same terrain, obstacles, or cultural features that appear on the PFD’s synthetic vision display in a consistent manner and not cause confusion to the crew when comparing the same feature across displays. This display could be on the navigation display, but also be an MFD or a third separate display. Ideally, the TAWS or HTAWS or terrain alerting C-1
Appendix C system should be part of this display (unless incorporated into the PFD) so that hazardous terrain or obstacles are highlighted.
C.3 Minimums Audio Callout Capability.
Applicants are encouraged to incorporate either a pilot selectable or automatic altitude alert with audio callout to remind pilots they are approaching minimums. Pilots may “see” the runway environment on their synthetic vision display and continue below minimums inadvertently because they were so intent on following the approach guidance. This scenario is similar to pilots fixating on a flight director and descending below minimums. Alerting pilots that they are nearing minimums reduces the opportunity for this situation to occur.
C.4 Digital Evaluation Model (DEM) Resolution.
The DEM resolution is one factor that determines how well the synthetic vision terrain depiction will match the terrain environment. National Aeronautics and Space Administration (NASA) experiments, documented in NASA/TP-2008-215130, Aspects of Synthetic Vision Display Systems and Best Practices of the NASA’s SVS Project and NASA/TP-2007-214864, Terrain Portrayal for Synthetic Vision Systems Head-Down Displays Evaluation Results, have shown that a terrain resolution of 30 arc-seconds (with arc-seconds referenced to an equatorial measurement) “rounds off” the terrain peaks and fills in valleys. This makes the terrain appear less hazardous for the peaks than it is and potentially reduces some safety benefit. Conversely, for the valleys, the terrain appears higher and its depiction is therefore conservative. The same set of NASA experiments pointed out that even though pilots preferred terrain created using higher resolutions (one and three arc-seconds), a synthetic vision display using a 30 arcsecond database could provide more situation awareness (and, therefore, safety) than the conventional instrument panel. Therefore, we had historically considered 30 arcsecond resolution the minimum safety standard for synthetic vision displays. This allowed for the introduction of synthetic vision systems given the technology limitations. However, technology has surpassed the need to allow as low a minimum resolution. New systems should meet 15 equatorial arc-seconds or better. Current systems do very well at twice the resolution minimum, but we want to encourage applicants to use the highest resolutions available in unclassified databases. Applicants may also consider using very high-resolution databases near airports while reducing the resolution in the rest of the database. However, for systems intended to support low altitude operations, for example helicopter operations, the use of high-resolution databases for all phases of flight might be more appropriate. More importantly, applicants should clearly define the resolution and measuring units of the DEM used by their synthetic vision system in the Aircraft Flight Manual Supplement (AFMS) and the pilots’ handbooks so that pilots can understand any visual limitation caused by resolution limits.
Note: The DEM resolution needed on a synthetic vision display depends on the intended function of that display. Applicants need to consider how they are going to use the terrain database information for their synthetic vision C-2
Appendix C display, and this information should be given to the FAA at the beginning of a synthetic vision certification program. Common elevation references are average elevation, maximum elevation, and sometimes, the elevation of the geometric center of the area. As post-spacing increases, the difference between the DEM value and the actual elevation of a point within a cell may differ significantly. The elevations used for a synthetic vision display should be conservative; use the highest elevation for a given cell. This concept is identical to the current sectional charts labeling the highest elevation in the given quadrangle (square sector) of latitude and longitude.
C.5 Aircraft Flight Manual Supplement (AFMS).
The AFMS should contain limitations for pilots on use of the applicant’s system. These limitations should be explained in detail. Warnings, cautions, and notes should also address the proper use and potential misuse of the display for terrain awareness and avoidance.
C.6 SVS Unusual Attitude Recovery.
Historically, the FAA required removal of all but essential flight information from the PFD in unusual attitudes. This “decluttering” was meant to aid pilots in recovering the aircraft. Therefore, the first synthetic vision systems removed the synthetic depiction and reverted to the traditional “blue-over-brown” display during unusual attitudes.
Based on a past report, the FAA Civil Aeronautical Medical Institute (CAMI) observed little performance difference between recoveries with and without the synthetic depiction. Furthermore, there was a possibility pilots might be temporarily confused by the significant change to their primary attitude display. Therefore, applicants should consider leaving the synthetic vision depiction on the PFD for unusual attitude recovery.
C.6.1 An accurate, easy, quick-glance interpretation of attitude should be possible for all unusual attitude situations. Information to perform effective manual recovery from unusual attitudes using chevrons, pointers and/or permanent ground-sky horizon on all attitude indications is recommended.
C.6.2 Pilots should be able to initiate a recovery toward the correct horizon and altitude within one second of recognition.
Note: For example, a test scenario could include climbing with a large mountain or plateau in the background into a stall condition or descending into rising terrain with decreasing airspeed into a stall condition.
C.6.3 The artificial horizon line and/or other attitude-related symbology (for example, aircraft symbol and pitch ladder) should be very prominent and highly visible against all possible backgrounds, including the assignment of a level of priority over other symbology on the display commensurate with its importance.
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Appendix D APPENDIX D. DEFINITIONS AND ACRONYMS D.1 Definitions D.1.1 Aircraft State Awareness Synthetic Vision System (RTCA DO-371) – A display of perspective view synthetic terrain and overlaid primary flight display symbology that is intended to enhance perception of aircraft motion and to enhance attitude and energy state awareness.
D.1.2 Appliance (14 CFR 1.1) - Any instrument, mechanism, equipment, part, apparatus, appurtenance, or accessory, including communications equipment, that is used or intended to be used in operating or controlling an aircraft in flight, is installed in or attached to the aircraft, and is not part of an airframe, engine, or propeller.
D.1.3 Approach Lighting Designators ALSF-I: Approach Light System with Sequenced Flashing Lights in ILS Cat I Configuration.
ALSF-II: Approach Light System with Sequenced Flashing Lights in ILS Cat II Configuration. The ALSF-II may operate as a SSALR when weather conditions permit.
MALSR: Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights.
SSALR: Simplified Short Approach Lighting System with Runway Alignment Indicator Lights.
MALSF: Medium Intensity Approach Lighting System with Sequenced Flashing Lights.
D.1.4 Command Guidance - Symbolic information that directs the pilot to follow a course of action to control attitude or thrust in a specific situation (for example, flight director).
D.1.5 Conformal (AC 25-11B) - Refers to displayed graphic information that is aligned and scaled with the outside view.
D.1.6 Decision Altitude (14 CFR 1.1) - A specified altitude in an instrument approach procedure at which the pilot must decide whether to initiate an immediate missed approach if the pilot does not see the required visual reference, or to continue the approach. Decision altitude is expressed in feet above mean sea level.
D.1.7 Decision Height (14 CFR 1.1) - A specified height above the ground in an instrument approach procedure at which the pilot must decide whether to initiate an immediate missed approach if the pilot does not see the required visual reference, or to continue the approach. Decision height is expressed in feet above ground level.
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Appendix D D.1.8 Egocentric - Used to define the view of a display image that correlates to inside the aircraft. One example is what the flight crew would see out the window from a forward facing perspective.
D.1.9 Exocentric - Used to define the view of a display image that correlates to outside the aircraft. One common exocentric view would be a North Up Plan view shown on moving map displays.
D.1.10 Eye Reference Point (ERP) - The point in the cockpit that allows for a finite reference enabling the precise determination of geometric entities that define the layout of the cockpit and displays.
D.1.11 Field of Regard (FOR) (SAE ARP 5677) - The angular extent of the external world that is represented on a display.
D.1.12 Field of View (FOV) - The angular extent of the display that can be seen by either pilot with the pilot seated at the pilot’s station. Refer to appropriate category of aircraft certification guidance for further information.
D.1.13 Flare Guidance - Provides explicit command guidance for the pilot to flare the aircraft.
D.1.14 Flare Prompt - The flare prompt advises the pilot when it is time to begin making the control inputs for the flare maneuver and transition to landing. A flare prompt does not provide command guidance to maneuver the airplane with regard to the rate or magnitude of manual inputs, alignment to runway heading nor touching down at a specific point on the runway.
D.1.15 Flicker (RTCA DO-315A) - High frequency luminance variations.
D.1.16 Flight Path Angle Reference Cue - Pilot selectable reference cue on the pitch scale displaying the desired approach angle.
D.1.17 Flight Path Vector - A symbol on the primary display (HUD, HUD equivalent, or PFD) that shows where the aircraft is actually going, the sum of all forces acting on the aircraft.
D.1.18 Flight Visibility (14 CFR 1.1) - The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects can be seen and identified by day and prominent lighted objects can be seen and identified by night.
D.1.19 Height Above Touchdown (HAT) (Aeronautical Information Manual) – The height of the Decision Height or Minimum Descent Altitude above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway). HAT is published on the instrument approach charts in conjunction with all straight-in minimums.
D.1.20 Head Up Display (HUD) (AC 25.1329-1C) - A transparent optical display system located level with and between the pilot and the forward windscreen. The HUD displays a combination of control, performance, navigation, and command information D-2
Appendix D superimposed on the external field of view. It includes the display element, sensors, computers and power supplies, indications, and controls. It is integrated with airborne attitude, air data, and navigation systems, and as a display of command information is considered a component of the flight guidance system.
D.1.21 HUD Equivalent Display (RTCA DO-315A) – A display with at least the following characteristics:
x A head-up presentation not requiring the transition of visual attention from head down to head up.
x Displays imagery and or/symbology conformal (as defined in SAE AS 8055) with the pilots external view.
x Permits simultaneous view of the imagery (if presented), aircraft flight symbology and the external view.
x Display characteristics and dynamics suitable for manual control of the aircraft.
D.1.22 Instrument (14 CFR 1.1) - A device using an internal mechanism to show visually or aurally the attitude, altitude, or operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling an aircraft in flight.
D.1.23 Instrument meteorological conditions (IMC) (14 CFR 170.3) - Weather conditions below the minimums prescribed for flight under Visual Flight Rules (VFR).
D.1.24 Jitter (RTCA DO-315A) - High frequency positional oscillations.
D.1.25 Latency (AC 25-11B) - The time taken by the display system to react to a triggered event coming from an input/output device, the symbol generator, the graphic processor, or the information source.
D.1.26 Minification – Perceived visual compression effect stemming from the display of imagery with a wider field of view than the conformal field of view of the display device.
D.1.27 Minification Factor – Field of view of the imagery being displayed to the pilot divided by the conformal field of view of the display.
D.1.28 Minimum Descent Altitude (14 CFR 1.1) - The lowest altitude specified in an instrument approach procedure, expressed in feet above mean sea level, to which descent is authorized on final approach or during circle-to-land maneuvering until the pilot sees the required visual references for the heliport or runway of intended landing.
D.1.29 Primary Flight Display (PFD) - The displays used to present primary flight information.
D.1.30 Rmax. The maximum range the radar can detect.
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Appendix D D.1.31 Situation Information (AC 120-29A, Criteria for Approval of Category I and Category II Weather Minima for Approach) - Information that directly informs the pilot about the status of the aircraft system operations or specific flight parameters including flight path.
D.1.32 Synthetic Vision (14 CFR 1.1) - A computer-generated image of the external scene topography from the perspective of the flight deck that is derived from aircraft attitude, high-precision navigation solution, and database of terrain, obstacles and relevant cultural features.
D.1.33 Synthetic Vision System (SVS) (14 CFR 1.1) - An electronic means to display a synthetic vision image of the external scene topography to the flight crew.
Note: “Topography” defined as maps or charts of natural and man-made features of a place or region especially in a way to show their relative positions and elevations, as applicable whenever deemed appropriate and practicable.
D.1.34 Synthetic Vision Guidance System (SVGS) (RTCA DO-359) - A guidance system which integrates a synthetic vision system scene depiction with additional functionality and display elements to support operations below standard precision approach operating minima. The additional display elements must include the runway of intended landing.
Additional functions must include a flight path vector and flight path angle reference cue. An SVGS must meet the minimum requirements for reliability, availability, and integrity to be used for operational credit.
D.1.35 Threshold Crossing Height (TCH) (Pilot/Controller Glossary) - The theoretical height above the runway threshold at which the aircraft’s glideslope antenna would be if the aircraft maintains the trajectory established by the mean ILS glideslope.
D.1.36 Visual References - Visual information the pilot derives from the observation of realworld cues, out the flight deck window, used as a primary reference for aircraft control or flight path assessment.
D.2 Acronyms.
Acronym Phrase AC Advisory Circular ACO Aircraft Certification Office AFMS Aircraft Flight Manual Supplement AGL Above Ground Level ASA-SVS Aircraft State Awareness Synthetic Vision System BIT Built In Test CAT Category CVS Combined Vision System DA Decision Altitude DEM Digital Elevation Model D-4
Appendix D Acronym Phrase DH Decision Height DQR Data Quality Requirements DTED Digital Terrain Elevation Data EASA European Union Aviation Safety Agency EFB Electronic Flight Bag EFIS Electronic Flight Instrument System EMI Electromagnetic Interference EVS Enhanced Vision System FAA Federal Aviation Administration FHA Functional Hazard Analysis FMEA Failure Mode and Effects Analysis FOR Field of Regard FOV Field of View FTA Fault Tree Analysis GPS Global Positioning Satellites HAT Height Above Touchdown HDD Head Down Display HIRF High Intensity Radiated Fields HMI Hazardously Misleading Information HTAWS Helicopter Terrain Awareness and Warning System HUD Head up Display IFR Instrument Flight Rules ILS Instrument Landing System LOC-I Loss of Control Inflight LPV Localizer Performance with Vertical guidance MASPS Minimum Aviation System Performance Standards MDA Minimum Descent Altitude MDH Minimum Descent Height MFD Multi-Function Display ND Navigation Display PFD Primary Flight Display RFM Rotorcraft Flight Manual RVR Runway Visual Range SA Special Authorization SSA System Safety Analysis STC Supplemental Type Certificate SVS Synthetic Vision System SVGS Synthetic Vision Guidance System TAWS Terrain Awareness and Warning System D-5
Appendix D Acronym Phrase TC Type Certificate TCH Threshold Crossing Height TDZE Touchdown Zone Elevation TSO Technical Standard Order VFR Visual Flight Rules VMC Visual Meteorological Conditions D-6
Appendix E APPENDIX E. RELATED PUBLICATIONS E.1 Related Publications.
E.1.1 FAA Documents:
E.1.1.1 Order 8110.4C, Type Certification.
E.1.1.2 Order 8110.54A, Instructions for Continued Airworthiness Responsibilities, Requirements, and Contents.
E.1.1.3 AC 20-115D, Airborne Software Development Assurance Using EUROCAE ED-12( ) and RTCA DO-178( ).
E.1.1.4 AC 20-152, RTCA, Inc., Document RTCA/DO-254, Design Assurance Guidance for Airborne Electronic Hardware.
E.1.1.5 AC 20-153B, Acceptance of Aeronautical Data Processes and Associated Databases.
E.1.1.6 AC 20-167B, Airworthiness Approval of Enhanced Vision System, Combined Vision System, and Enhanced Flight Vision System Equipment.
E.1.1.7 AC 21-16G, RTCA Document DO-160 versions D, E, F, and G, “Environmental Conditions and Test Procedures for Airborne Equipment.
E.1.1.8 AC 23-18, Installation of Terrain Awareness and Warning System (TAWS) Approved for Part 23 Airplanes.
E.1.1.9 AC 23.1309-1E, System Safety Analysis and Assessment for Part 23 Airplanes.
E.1.1.10 AC 23.1311-1C, Installation of Electronic Display in Part 23 Airplanes.
E.1.1.11 AC 25-11B, Electronic Flight Displays.
E.1.1.12 AC 25-23, Airworthiness Criteria for the Installation Approval of a Terrain Awareness and Warning System (TAWS) for Part 25 Airplanes.
E.1.1.13 AC 25.571-1D, Damage Tolerance and Fatigue Evaluation of Structure.
E.1.1.14 AC 25.629-1B, Aeroelastic Stability Substantiation of Transport Category Airplanes.
E.1.1.15 AC 25.1309-1A, System Design and Analysis.
E.1.1.16 AC 25.1329-1C, Change 1, Approval of Flight Guidance Systems.
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