Appendix 1 ET Error Term [FMS use] ETOPS Extended Range Operations with Two-Engine Airplanes EVS Enhanced Vision System FAF Final Approach Fix FAP Final Approach Point FAR Federal Aviation Regulation FAS Final Approach Segment FBS Fixed Base Simulator FBW Fly-by-wire FCOM Flightcrew Operating Manual FDR Flight Data Recorder FGS Flight Guidance System FHA Functional Hazard Assessment FLIR Forward Looking Infrared Sensor FM Frequency Modulation FM Fan Marker FMC Flight Management Computer FMS Flight Management System FPAP Flight Path Alignment Point FPA Flight Path Angle FPCP Flight Path Control Point FSB Flight Standardization Board FSDO (FAA) Flight Standards District Office FSS (FAA) Flight Service Station FTE Flight Technical Error GA Go-Around GBAS Ground Based Augmentation System GCA Ground Controlled Approach GIRP Glidepath Intercept Reference Point GLS GPS (or GNSS) Landing System GNSS Global Navigation Satellite System GPA Glide Path Angle GPIWP Glide Path Intercept Waypoint GPWS Ground Proximity Warning System
Appendix 1 GPS Global Positioning System HAA Height Above Airport HAT Height above Touchdown HDG Heading HQRS Handling Quality Rating System (see AC25-7A, as amended) HUD Head Up Display IAP Instrument Approach Procedure IAW In Accordance With ICAO International Civil Aviation Organization IFR Instrument Flight Rules IM Inner Marker IMAS Initial Missed Approach Segment IMAWP Initial Missed Approach Waypoint IMC Instrument Meteorological Conditions ILS Instrument Landing System INAS International Airspace System IOE Initial Operating Experience IRS Inertial Reference System IRU Inertial Reference Unit JAA Joint Aviation Authority JAR AWO Joint Aviation Regulations – All Weather Operations KRM (Type of Landing system used in certain foreign States) LAAS Local Area Augmentation System LAD Local Area Differential LAHSO Land And Hold Short Operation LDA Localizer-Type Directional Aid (approach type) LLM Lower Landing Minima LMM Compass Locator Middle Marker LLTV Low Light Level TV LNAV Lateral Navigation LOA Letter of Authorization LOC (ILS) Localizer LOE Line Operational Evaluation LOFT Line Oriented Flight Training
Appendix 1 LOM Compass Locator Outer Marker LOS Line Oriented Simulation MAP Mode Annunciator Panel MAP Missed Approach Point MAS Missed Approach Segment MASPS Minimum Aviation System Performance Standards MB Marker Beacon MCP Mode Control Panel MDA Minimum Descent Altitude MDA(H) Minimum Descent Altitude (Height) MDH Minimum Descent Height - NOTE: MDH is not used for U.S. Operations MEH Minimum Engage Height MEL Minimum Equipment List METAR ICAO Routine Aviation Weather Report MLS Microwave Landing System MM Middle Marker MMEL Master Minimum Equipment List MMR Multi-mode Receiver MOT Ministry of Transport MRB Maintenance Review Board MSL Mean Sea Level (altitude reference datum) MUH Minimum Use Height MVA Minimum Vectoring Altitude NA Not Authorized or Not Applicable NAS National Airspace System NAVAID Navigational Aid ND Navigation Display NDB Navigation Data Base NDB Non-directional Beacon NOTAM Notice to Airman NRS National Resource Specialist OCA Obstacle Clearance Altitude OCH Obstacle Clearance Height OCL Obstacle Clearance Limit
Appendix 1 OIS Obstacle Identification Surface OM Outer Marker OSAP Offshore Standard Approach Procedure PAI Principal Avionics Inspector PAR Precision Approach Radar PC/PT Proficiency Check/Proficiency Training PF Pilot Flying PFC Porous Friction Coarse (runway surface) PIC Pilot in Command PIREP Pilot Weather Report PNF Pilot Not Flying PoC Proof of Concept POI Principal Operations Inspector PMI Principal Maintenance Inspector PRD Progressive Re-Dispatch PRM Precision Radar Monitor PTS Practical Test Standard QFE Altimeter Setting referenced to airport field elevation QNE Altimeter Setting referenced to standard pressure (1013.2HPa or 29.92”) QNH Altimeter Setting referenced to airport ambient local pressure QRH Quick Reference Handbook RA Radio Altitude or Radar Altimeter RAIL Runway Alignment Indicator Light System RCLM Runway Center Line Markings RCP Required Communication Performance RDMI Radio Direction Magnetic Indicator RDP Runway Datum Point REIL Runway End Identification Lights RII Required Inspection Item RMI Radio Magnetic Indicator RMP Required Monitoring Performance (e.g., surveillance) RMS Root-mean-square RNAV Area Navigation RNP Required Navigation Performance
Appendix 1 RNPx2 RNP Containment Limit (2 times RNP value) RSP Required System Performance (Considers RNP, RCP, and RMP) RTCA An industry standard setting organization - formerly known as the “Radio Technical Commission for Aeronautics” RTS Return to Service RTO Rejected Takeoff RVR Runway Visual Range RVV Runway Visibility Value RWS Runway Segment RWY Runway SA Selective Availability SARPS ICAO Standards and Recommended Practices SBAS Space Based Augmentation System SDF Simplified Directional Facility SFL Sequence Flasher Lights SIAP Standard Instrument Approach Procedure SID Standard Instrument Departure - Note: This term is no longer in use in the U.S., and has been replaced by the term Departure Procedure (DP) SLA Standard Landing Aid SLF Supervised Line Flying SMGC Surface Movement Guidance Control SMGCP Surface Movement and Guidance Plan SMGCS Surface Movement Guidance Control System STAR Standard Terminal Arrival Route STC Supplemental Type Certificate STOL Short Takeoff and Landing SRE (Type of Landing system used in certain foreign States) SV Space Vehicle TACAN Tactical Air Navigation system (NAVAID) TAF Terminal Aviation Forecast TAWS Terrain Awareness Warning System TC Type Certificate TCH Threshold Crossing Height TDZ Touchdown Zone TERPS U.S. Standard for Terminal Instrument Procedures
Appendix 1 TLS Target Level of Safety TOGA Takeoff or Go-Around (FGS Mode) TSE Total system error ua micro amps VGSI Visual Glide Slope Indicator VDP Visual Descent Point VFR Visual Flight Rules VHF Very High Frequency VIS Visibility VOR VHF Omni-directional Radio Range VORTAC Co-located VOR and TACAN VMC Visual Meteorological Conditions VNAV Vertical Navigation V1 Takeoff Decision Speed Vef Engine Failure Speed Vfailure Speed at which a failure occurs Vlof Liftoff Speed Vmcg Ground Minimum Control Speed WAAS Wide Area Augmentation System WAD Wide Area Differential WAT Weight, Altitude, and Temperature WGS World Geological Survey WGS-84 World Geological Survey - 1984 WP Waypoint xLS (Generic term used to denote any one or more of the following NAVAIDs: ILS, MLS, or GLS)
Appendix 2 APPENDIX 2. AIRBORNE SYSTEMS FOR CATEGORY I Mandatory terms used in this AC such as “shall” or “must” are used only in the sense of ensuring applicability of these particular methods of compliance when the acceptable means of compliance described herein is used. This AC does not change, add, or delete regulatory requirements or authorize deviations from regulatory requirements.
1. PURPOSE. This appendix contains airworthiness criteria for the approval of aircraft equipment and installations required to conduct an approach in Category I weather minima.
2. GENERAL.
The type certification approval for the equipment, system installations, and test methods should be based on a consideration of factors such as the intended function of the installed system, its accuracy, reliability, and fail-safe features, as well as the operational concepts contained in the body of this Advisory Circular (AC). The guidelines and procedures contained herein are considered acceptable methods of determining transport category airplane airworthiness to conduct an approach in Category I weather conditions.
The overall assurance of performance and safety of an operation can only be assessed when all elements of the system are considered. This appendix includes a discussion of the non-aircraft elements of a system so that an overall assessment of the operation can be accomplished.
References to JAA All Weather Operations Regulations are provided to facilitate the All Weather Operations Harmonization process. A reference to a JAR provision does not necessarily mean that the FAA and JAA requirements are equivalent but that they are related with similar intent. The FAA typically may identify which JAR provisions are acceptable to FAA at the time a type certification basis is established.
3. INTRODUCTION.
This appendix addresses the approach phase of flight. For the purpose of this appendix, the approach phase of flight is defined as the flight segment from the Final Approach Fix (FAF) to the Category I decision altitude/height. This appendix provides criteria, which represents an acceptable means of compliance with performance, integrity and availability requirements for low visibility approach. An applicant may propose alternative criteria. With new emerging technologies, there is a potential for many ways of conducting low visibility approach operations. This appendix does not attempt to provide criteria for each potential combination of airplane and non-airplane elements.
a. Operations using current ILS or MLS ground-based facilities and airplane elements are in use, and the certification criteria for approval of these airplane systems are established. Other operations, using non-ground based facilities or evolving ground facilities (e.g., local or wide area augmented Global Navigation Satellite System (GNSS)), and the use of some new aircraft equipment require Proof of Concept testing to establish appropriate criteria for operational approval and system certification. The need for a Proof of Concept program is identified in this AC with a [PoC] designator. This appendix provides some general guidelines, but not comprehensive criteria, for airplane systems that require a Proof of Concept.
b. The intended flight path may be established in a number of ways. For systems addressed by this appendix, the reference path may be established by a navigation aid (e.g., ILS, MLS). Other methods may be acceptable if shown feasible by a Proof of Concept [PoC]. Methods requiring PoC include, but are not limited to:
• the use of ground surveyed waypoints, either stored in an on-board data base or provided by data link to the airplane, with path definition by the airborne system,
• sensing of the runway environment (e.g., surface, lighting and/or markings) with a vision enhancement system.
Appendix 2 On-board navigation systems may have various sensor elements by which to determine airplane position. The sensor elements may include ILS, MLS, GNSS with ground-based augmentation (GLS), or inertial information. Each of these sensor elements should be used within appropriate limitations with regard to accuracy, integrity and availability.
Indications of the airplane position with respect to the intended path can be provided to the pilot in a number of ways.
• deviation displays with reference to navigation source (e.g., Instrument Landing System (ILS) receiver, Microwave Landing System (MLS) receiver), or
• on-board navigation system computations with corresponding displays of position and reference path, or
• by a vision enhancement system. [PoC]
c. The minimum visibility required for safe operations with such systems and backup means will be specified by FAA Flight Standards in the operational authorization.
4. TYPES OF APPROACH OPERATIONS. The airworthiness criteria in this appendix are intended to be consistent with the operational concepts of paragraph 4.3 of the main body of this AC.
4.1. Operations based on a Standard Landing Aid.
ILS and MLS have been characterized by appropriate International Civil Aviation Organization (ICAO) standards, and for the purpose of certification in accordance with this Appendix may be considered a Standard Landing Aid.
Landing Systems based on the GLS may use interim U.S. criteria, or other FAA-agreed State criteria, or other international standards developed for acceptable combination of space and ground-based elements. Acceptable overall aircraft performance may be established based upon the assumption that these services are used and maintained to the specified standards identified, or as specified in the applicable airworthiness approval.
4.2. Operations based on Required Navigation Performance (RNP). The airworthiness criteria in this appendix support the operational concept for RNP as described in paragraph 4.5 in the main body of this AC.
4.2.1. Standard RNP Types. Approach operations may be specified based upon standard RNP type designations.
The type designation identifies the performance standard required to conduct the operation. The RNP Type will have a lateral performance component and may additionally have a vertical component. Refer to Paragraph 4.5.1 in the main body of this AC for Standard RNP Types.
4.2.2. Non-standard RNP Types. Some operations may be approved for Non-Standard RNP Types - refer to paragraph 4.5.2 in the main body of this AC. It is envisioned that the airplane systems approval process for Non- Standard RNP Types will be equivalent to that used for Standard RNP Types unless otherwise agreed with the FAA.
4.3. Operations based on Area Navigation System(s). Paragraphs 4.3.3 through 4.6 of the main body of this AC provide the criteria for operational authorization of the use of area navigation systems for approach.
a. Instrument approach operations may be approved using aircraft area navigation with lateral and vertical or lateral only capability. The navigation system will typically use multi-sensor capability for position fixing (VHF Omni-directional Radio Range (VOR), Distance Measuring Equipment (DME), Global Positioning System (GPS), Inertial Reference System (IRS), Instrument Navigation System (INS), etc.,) to achieve the necessary performance for certain levels of Category I operations.
Appendix 2
b. Required levels of accuracy, integrity, and availability for various combinations of sensor-dependent operations (e.g., ILS, GLS, VOR, NDB) or area navigation operations (e.g., Lateral Navigation/Vertical Navigation (LNAV/VNAV), LNAV only, or RNP), necessary to support either Category I or Category II instrument approach procedures, as applicable, are specified in paragraph 5 of the main body of this AC.
5. TYPES OF APPROACH NAVIGATION SERVICE.
5.1. Instrument Landing System (ILS).
ILS is supported by established international standards for ground station operation. These standards should be used in demonstrating airplane system operation.
The Airplane Flight Manual (AFM) shall indicate that operation is predicated upon the use of an ILS facility with performance and integrity equivalent to, or better than, an ICAO Annex 10 Facility Performance Category I ILS, a U.S. Type I, or equivalent.
5.1.1. ILS Flight Path Definition. The required lateral and vertical flight path is inherent in the design of the ILS.
Acceptable performance and integrity standards have been established for ILS.
5.1.2. ILS Airplane Position Determination. The airplane lateral and vertical position relative to the desired flight path is accomplished by an airplane ILS receiver that provides deviation from the extended runway centerline path when in the coverage area.
5.2. Microwave Landing System (MLS).
MLS is supported by established ICAO Annex 10 international standards for ground station operation. These standards should be used in demonstrating airplane system operation.
The AFM shall indicate that operation is predicated upon the use of an MLS facility with performance and integrity equivalent to, or better than, an ICAO Annex 10 Facility Performance Category I MLS, or equivalent.
5.2.1. MLS Flight Path Definition. The lateral and vertical required flight path is inherent in the design of the MLS. Acceptable performance and integrity standards have been established for MLS.
5.2.2. MLS Airplane Position Determination. The airplane lateral and vertical position relative to the desired flight path is accomplished by an airplane MLS receiver that provides deviation from the extended runway centerline path when in the coverage area.
5.3. GNSS with Ground-based Augmentation (GLS) [PoC].
This appendix section is not intended to provide a comprehensive means of compliance for airworthiness approval of GNSS based systems. Currently approved systems are ILS or MLS-based. The application of new technologies and systems will require an overall assessment of the integration of the airplane components with other elements (e.g., new ground-based aids, satellite systems, advanced radar mapping systems, enhanced vision sensor systems) to ensure that the overall safety of the use of these systems for Category I. This GNSS section is included to identify important differences between conventional ILS/MLS-based systems and GNSS based systems that affect GLS criteria development.
The performance, integrity, and availability of any ground station elements, any datalinks to the airplane, any satellite elements and any data base considerations, when combined with the performance, integrity, and availability of the airplane system, should be at least equivalent to the overall performance, integrity, and availability provided by ILS to support Category I operations.
Appendix 2
5.3.1. GLS Flight Path Definition. Appropriate specification of the required flight path for approach, or approach, landing, and rollout (as applicable), is necessary to assure safety of the operation to the relevant operational minima.
The required flight path should be established to provide adequate clearance between the airplane and fixed obstacles on the ground, between airplanes on adjacent approaches, and to ensure that the airplane stays within the confines of the runway.
a. The effect of the navigation reference point on the airplane flight path and wheel-to-threshold crossing height must be addressed.
b. The required flight path is not inherent in the design of a GNSS based approach, landing, and rollout system;
therefore, an airplane navigation system must specify a sequence of earth-referenced path points, or the airplane must receive information from a ground-based system to define the approach, landing, and rollout required path points.
c. Certain path points, waypoints, leg types, and other criteria are necessary to safely implement the approach, or approach, landing, and rollout operations based on satellite and other integrated multi-sensor navigation systems.
d. Figure 4.6-1 in the main body of this AC shows the minimum set of path points, waypoints, and leg types considered necessary to specify the flight path for approach, or approach, landing, and rollout operations.
e. The required flight path may be stored in an airplane database for recall and use by the command guidance and/or control system when required to conduct the approach to relevant minima for landing and rollout.
f. The definition, resolution, and maintenance of the waypoints which define the required flight path and flight segments is key to the integrity of this type of approach, landing, and rollout operation.
g. A mechanism should be established to assure the continued integrity of the flight path designators.
h. The integrity of any database used to define required path points for an approach should be addressed as part of the certification process. The flightcrew shall not be able to modify information in the database that relates to the definition of the required flight path for the final approach, and, if necessary, initial missed approach.
5.3.2. GLS Airplane Position Determination. The safety of an approach operation is, in part, predicated on knowing where the airplane is positioned relative to the required flight path. Navigation satellite systems exist which can provide position information to specified levels of accuracy, integrity, and availability. The accuracy, integrity, and availability can be enhanced by additional space and ground-based elements. These systems provide certain levels of capability to support present low visibility operations and are planned to have additional future capability.
a. Satellite systems have the potential to provide positioning information necessary to guide the airplane during approach. If operational credit is sought for these operations, the performance, integrity, and availability must be established to support that operation. Ground-based aids such as differential position receivers, pseudolites etc., and a data link to the airplane may be required to achieve the accuracy, integrity, or availability for certain types of operation.
b. A level of safety equivalent to current ILS-based operations should be established.
c. The role of the satellite-based elements in the landing system should be addressed as part of the airplane system certification process until such time as acceptable national or international standards for satellite-based systems are established.
Basic GNSS (Un-augmented). This is the basic navigation service provided by a satellite system. No additional navigation service elements are used to enhance accuracy or integrity of the operation.
Appendix 2 Differential Augmentation. The role of the differential station in the landing system should be addressed as part of the airplane system certification process, unless an acceptable national or international standard for the ground reference system is established.
Local Area Differential Augmentation. Local Area Differential (LAD) augmentation consists of a set of ground-based GNSS receivers that are used to derive pseudo-range corrections and integrity data referenced to a point on or near the airport. This augmentation data is then provided to the airplane via a local, ground-based data broadcast signal.
Wide Area Differential Augmentation. Wide Area Differential (WAD) augmentation may be used to provide approach capability supporting appropriate levels of Category I procedures.
5.3.3. Data Link [PoC]. A data link may be used to provide data to the airplane to provide the accuracy necessary to support certain operations (e.g., navigation waypoints, differential corrections for GNSS).
a. The integrity of the data link should be commensurate with the integrity required for the operation.
b. The role of the data link in the approach, or approach and landing system should be addressed as part of the airplane system certification process unless an identified acceptable U.S. or international standard(s) for the data link ground system is applicable and is used.
6. BASIC AIRWORTHINESS REQUIREMENTS. This section identifies airworthiness requirements including those for performance, integrity, and availability that apply to all types of airplane systems, independent of the type of approach and landing or navigation system used. The definitions of performance, integrity, and availability are found in Appendix 1. The basic airworthiness criteria are intended to be independent of the specific implementation in the airplane or the type of approach system being used. Criteria may be expanded further in later sections of this appendix as it applies to a particular airplane system or architecture.
NOTE: Continuity of Approach Function may involve aircraft systems, ground systems and, in some cases, space-based systems. This AC addresses the aircraft part of the system and aircraft criteria will be defined in terms of aircraft system availability to provide quantifiable criteria for airworthiness compliance.
6.1. General Requirements. An applicant shall provide a certification plan which describes how any non-aircraft elements of the Approach System relate to the aircraft system from a performance, integrity and availability perspective. Standard Landing Aids (SLA) can be addressed by reference to ICAO Standards and Recommended Practices (SARPS).
a. The plan for certification shall describe the system concepts and operational philosophy to allow the regulatory authority to determine whether criteria and requirements other than those contained in this appendix are necessary.
b. The Approach system performance should be established considering the environmental and deterministic effects that may reasonably be experienced for the type of operation for which certification and operational approval will be sought.
c. Where reliance is placed on the pilot to detect a failure of engagement of a mode when it is selected (e.g., goaround), an appropriate indication or warning must be provided.
d. The effect of the failures of the navigation facilities must be considered taking into account ICAO and other pertinent State criteria.
e. The effect of the aircraft navigation reference point on the airplane flight path and wheel-to-threshold crossing height shall be assessed.
Appendix 2
6.2. Approach System Accuracy Requirements. The following items are general criteria that apply to the various types of approach operations.
a. Performance shall be demonstrated by flight test, or analysis validated by flight test, using at least 3 different representative facilities for a minimum of 9 total approaches, with a representative range of environmental and system variables which have an effect on overall performance.
b. The performance assessment shall take into account at least the following variables with the variables being applied based upon their expected distribution:
(1) Configurations of the airplane (e.g., flap settings);
(2) Center of gravity;
(3) Landing weight;
(4) Conditions of wind, turbulence, and wind shear;
(5) Characteristics of ground and space based systems and aids (e.g., ILS, MLS, GLS, GNSS); and
(6) Any other parameter which may affect system performance (e.g., airport altitude, approach path slope, variations in approach speed).
c. The criteria for acceptable approach performance are based upon acquiring and tracking the required flight path to the appropriate minimum altitude for the procedure. The acquisition should be accomplished in a manner compatible with instrument procedure requirements and flightcrew requirements for the type of approach being conducted.
d. An approach guidance system shall not generate command information (e.g., flight director, HUD etc.) which results in flight path control that is oscillatory or requires unusual effort by the pilot to satisfy the performance requirements.
e. An approach control system shall not generate flight path control (e.g., autopilot) with sustained oscillations.
f. The approach system must cause no sustained nuisance oscillations or undue attitude changes or control activity as a result of configuration or power changes or any other disturbance to be expected in normal operation.
6.2.1. ILS. The performance standards for signal alignment and quality contained in ICAO Annex 10 or an equivalent State standard are acceptable standards for operations based on ILS. These standards shall be used in establishing the performance of the operation.
a. Lateral tracking performance from 1000’ Height Above Touchdown (HAT) to 200’ HAT should be stable without large deviations (i.e., within ±50 microamps deviation) from the indicated course.
b. Vertical tracking performance from 700’ HAT to 200’ HAT should be stable without large deviations (i.e., within ±75 microamps deviation) from the indicated path.
6.2.2. MLS. The performance standards for signal alignment and quality contained in ICAO Annex 10 or an equivalent State standard are acceptable standards for operations based on MLS. These standards shall be used in establishing the performance of the operation.
a. Lateral tracking performance from 1000’ HAT to 200’ HAT should be stable without large deviations (i.e., within ±50 microamps deviation) from the indicated course or path.