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b. 3D RNAV procedures based on acceptable full capability GNSS/SBAS(WAAS) augmentation
4.3.7.4. “3D” RNAV Procedures - Minima not less than 250 feet DA(H). Instrument approach operations that may be authorized Category I minima not less than 250 ft. DA(H) include:
a. NAVAID specific procedures flown using RNAV lateral and vertical guidance (e.g., “VOR Rwy 16R” flown using acceptable FMS LNAV and VNAV) such as a VOR, VOR/DME, NDB, Localizer, or Localizer Back Course approach flown using RNAV, when the procedural identified NAVAID(s) are referenced in the FMS position determination, or when the procedure is flown with the crew monitoring the specified facility(s) by instrument display cross reference (e.g., RDMI raw data display, or equivalent);
b. RNAV (FMS LNAV/VNAV) Procedures overlaying a NAVAID-specific procedure, when FMS position updating is referenced to “data base procedural tuning” of the specified facility(s) (e.g., “RNAV or VOR Rwy 16R” flown using acceptable LNAV and VNAV, with FMS using the appropriate procedurally identified NAVAID(s) along with any other applicable sensors for position determination);
c. RNAV (FMS LNAV/VNAV) Procedures overlaying a NAVAID-specific procedure, when FMS position updating is not based on the “data base procedural tuning” of the specified facility(s), but instead is based on the FMS’s selection of optimum NAVAIDs or sensors (e.g., “RNAV or VOR Rwy 16R” flown using an FMS which is using optimally identified sensors or NAVAID(s) combinations for position determination); These procedures may be flown with or without the underlying NAVAID operational;
d. RNAV (FMS LNAV/VNAV) Procedures not based on a specific ground based NAVAID, when suitable FMS position updating is used (e.g., a “GPS Approach” flown using a suitably capable FMS and appropriate updating capability); or
e. RNAV RNP based procedures with levels of RNP or vertical navigation capability other than as qualify paragraph under 4.3.7.2.
4.3.7.5. “2D” RNAV Procedures (e.g., VOR/DME-based RNAV, or GPS-based RNAV) - Minima not less than 250 ft. MDA(H). Instrument approach operations in this group may be authorized Category I minima of not less than 250 ft. MDA(H).
a. This group includes at least the following:
• 2D RNAV based on sensor inputs from GPS
• 2D RNAV based on sensor inputs from DME/DME
• 2D RNAV based on sensor inputs from VOR/DME
• 2D RNAV based on sensor inputs from combinations of LOC and VOR or DME
b. RNAV (2D - LNAV only) Procedures overlaying a NAVAID-specific procedure (e.g., FMS/RNAV, used to fly an underlying VOR or NDB approach, but flown as a 2D RNAV procedure - without procedural tuning of the specified NAVAID facility);
c. RNAV (FMS LNAV/VNAV) Procedures not based on a specific ground based NAVAID, when suitable FMS position updating is used (e.g., a “GPS Approach” flown using a suitably capable FMS and appropriate updating capability); or
d. Other FAA authorized RNAV-based approach procedures (e.g., Loran, Airborne radar).
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4.3.7.6. Procedures Other than xLS or RNAV (e.g., VOR, NDB, LOC, Back Course LOC, or ASR Procedures) - Minima not less than 250 ft. MDA(H). Instrument approach operations in this group may be authorized Category I minima of not less than 250 ft. MDA(H).
a. This group includes ICAO or U.S. NAVAID-specific procedures other than those based on xLS or RNAV, including at least the following:
• VOR
• VOR/DME
• NDB
• NDB/DME
• LOC
• LOC Back Course
• LDA, and
• SDF
b. NAVAID-specific procedures as listed in item (1) above, but when flown with vertical guidance (e.g., using VNAV)
c. NAVAID-specific procedures as listed in item (1) above, but when flown with an “open loop” vertical speed based descent profile, and
d. Radar Surveillance Approach Procedures including ASR.
4.3.7.7. Other Special Procedures or Authorizations. Other special procedures or authorizations may be issued as follows:
a. Lower than Standard Category I minima authorizations may be issued, as addressed in FAA Order 8400.13
(e.g., Authorization for HUD or Autoland RVR 1800 minima, when using limited facilities for approach lighting and runway lighting).
b. Special Obstacle Assessment Procedures may be issued for a particular runway, operator, or a group of Operators (e.g., KDTW RW21R). Special Authorization to use a 200 ft. HAT DA(H) based on an obstacle assessment of the runway touchdown zone region and operator use of flight director or autoflight guidance systems.
c. Airborne Radar Approach authorizations may be issued to qualified applicants, for use with qualified airborne systems.
d. Special Limited Use (Non-ICAO) Procedures (e.g., TLS, KRM).
4.3.7.8. Previously Approved Category I Operations or Use of Previous or New Category I Criteria.
Operators approved IAW criteria of earlier versions of AC 120-29 (e.g., AC 120-29 Change 3) for Category I, or operating IAW approved OpSpecs for instrument approaches other than ILS, MLS, or GLS may continue to operate IAW their previously approved program, consistent with current standard operations specifications or any special provisions approved for that operator in that Operator’s approved operations specifications.
a. Approval criteria used for a particular aircraft are typically listed in an AFM. If not shown in an AFM, the applicable FAA Aircraft Evaluation Group (AEG) may be consulted through the POI or CMO, to determine eligibility.
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b. Aircraft qualified using other than FAA criteria will be as designated in approved OpSpecs or as designated by the applicable AEG (e.g., through the FAA Flight Standardization Board Report for the aircraft type) or AFS-400.
c. Aircraft demonstrated to meet airworthiness provisions of previous versions of AC 120-29 through Change 3, or criteria previous to AC 120-29, may remain eligible for previously approved operational authorizations.
Additional airworthiness demonstration under provisions of this AC are not necessary for these aircraft unless additional credit based on meeting the criteria in the appendices of this AC is specifically sought.
d. Operators seeking credit provided for only by this version of AC 120-29A and which were not available in previous versions of AC 120-29 must meet operational criteria as described in the main body of this AC.
e. New airworthiness approvals addressing Category I, intended for use by an air carrier, may use criteria earlier than this AC only on a case by case basis as determined by FAA. Examples of cases where criteria prior to this AC may be acceptable include providing information from a service bulletin based on a previous version of AC 120-29 to ensure compliance status of an “in-service” aircraft. Another situation would be for continuing the production and delivery of an aircraft or autoflight system type which had a type certification basis using a preceding version of this AC, or when seeking certification of a new derivative aircraft which has an autoflight system the same as or very similar to one previously approved based on an earlier version of AC 120-29.
4.3.8. Requirements for Category II.
4.3.8.1. General Category II Requirements. The following requirements apply to the operational authorization of Category II instrument approach procedures:
a. The airborne system should meet the requirements of the applicable paragraph of 5.2 for the type of Category II procedures to be flown,
b. Appropriate NAVAIDs and airport/lighting facilities for the procedures to be flown, consistent with Paragraph 8, should be available,
c. Flightcrew qualification consistent with provisions of Paragraph 7 for Category II has been completed,
d. An acceptable airworthiness program for the airborne system is provided IAW Paragraph 9, and
e. An operational authorization has been completed per Paragraph 10 for a U.S. operator or Paragraph 11 for a Non-U.S. operator.
4.3.8.2. Specification of a Category II DA(H). To simplify description of Category II operations and minima, the lowest authorized DA(H) for Category II is cited in this paragraph as an equivalent DH related to wheel height above touchdown zone elevation (e.g., HAT value of 100 ft.). This is done even though operational minima for Category II are typically specified as an equivalent DH value based on radio altitude height above the underlying approach terrain.
a. DH for a Category II procedure may be set and procedurally identified by the following nominal conditions:
(1) The aircraft’s navigation reference point tracks the center line of the glide path and FAS,
(2) Standard wheel to navigation reference point height and distance assumptions are used,
(3) A 100 foot or 150 foot wheel height HAT is assumed for the landing aircraft at DH, depending on minima to be specified, and
(4) A determination is made of the actual radio altitude above underlying terrain that occurs when an aircraft with nominal wheel to navigation reference height reaches the point on approach where its wheel height first reaches 100 ft. HAT.
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b. Alternately a Category II DH may be set based on specifying use of a 100 foot DH above underlying terrain, regardless of circumstance in which the 100 foot above terrain point is reached. In this instance, the first point or time in which any aircraft, with any arbitrary wheel to navigation reference height, pitch attitude, configuration, lateral displacement, or speed, first reaches the point at which 100 ft. radio altitude is indicated above underlying terrain, the aircraft is considered to have reached DH.
c. While a DA is conceptually not precluded for use with Category II, DAs are not currently operationally used for Category II, except as a backup for inner marker-based minima when irregular terrain precludes reliable radio altimeter use to determine minima.
4.3.8.3. Eligibility for Category II Minima not less than 100 ft. DA(H). Instrument approach operations that may be authorized Category II minima not less than 100 ft. DA(H) include:
a. ILS,
b. GLS (GBAS/LAAS), and
c. MLS.
4.3.8.4. Use of Inner Marker. Use of Inner Marker may be authorized in lieu of a DA(H). An Inner Marker is typically used at runways designated by the applicable procedure, such as where radar altimeter use is limited due to irregular underlying terrain (e.g., RA NA).
4.3.8.5. Barometric Altimeter DAs not currently used for 14 CFR Parts 121 or 135 Category II. Barometric altimeter-specified DAs are not currently used as a basis for minima for air carrier Category II, except for those Operators electing to discontinue an approach upon reaching either the DA or DH, which ever is reached first, when visual reference is not established, or upon reaching either the DA or IM, which ever is reached first, when using an IM as the basis for Category II minima.
4.3.8.6. Category II on U.S. Type I ILS. Category II on FAA Type I ILS (limited to FAA-specified locations) for certain qualified flight guidance systems. Instrument approach operations may be authorized Category II minima not less than 100 ft. DA(H). Criteria for special authorizations for air carriers to conduct Category II operations on certain FAA Type I ILS facilities is contained in FAA Order 8400.13
4.3.8.7. Category II using RVR 300 “Meter” Minima. Category II using RVR300m minima (at designated international locations) may be authorized when meeting special provisions of Standard OpSpecs paragraph C059a Table 1. (see Appendix 7). This provision permits an operator to be authorized use of Non-U.S. State minima of RVR300m with a DA(H) of 100 ft. HAT at certain international runways qualifying for a minima less than that specified by ICAO for Category II. A flight guidance system meeting provisions of Appendix 7, Paragraph C059, paragraph c, is required. Corresponding flightcrew procedures must be used. Following successful operational experience using this provision, FAA may determine that the above authorization may be also acceptable using an auto-coupled approach to 100 ft. HAT or other flight guidance system (e.g., HUD) without necessarily meeting other provisions for Category III. Following successful operational experience using this provision, FAA may determine that the above authorization may also be approved for use at certain U.S. facilities having appropriate Category II procedures with a minimum RVR of 1000 and a DA(H) of 100 ft. HAT. For use of this provision internationally, where such operations are authorized by the State of the Aerodrome (e.g., certain European airports), FAA considers the operation to be the equivalent of a limited U.S. Category III operation (1000RVR), even though the State may locally classify or consider it to be Category II.
4.3.8.8. Precision Approach Radar (PAR). Precision Approach Radar Minima may be authorized to minima of not less than 200 ft. HAT, or the published PAR minima, whichever is higher. PAR authorizations are limited to those Operators and crews specifically qualified to use PAR. Request for PAR operations with minima below 200 ft. HAT are approved only on a case by case basis, considering any special crew qualification required, the aircraft type and its characteristics (e.g., aircraft size, aircraft geometry, and PAR radar signature), and the specific facilities to be used.
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4.3.8.9. Previously Approved Category II Operations or Use of Previous or New Category II Criteria.
Operators approved IAW earlier versions of AC 120-29 (e.g., AC 120-29 Change 3) for Category II may continue to operate IAW their previously approved program, consistent with current standard OpSpecs or any special provisions approved for that operator in that Operator’s approved OpSpecs.
a. Approval criteria used for a particular aircraft are typically listed in an AFM. If not shown in an AFM, the applicable FAA Aircraft Evaluation Group (AEG) may be consulted through the POI or CMO, to determine eligibility.
b. Aircraft qualified using other than FAA criteria will be as designated in approved OpSpecs or as designated by the applicable AEG (e.g., through the FAA Flight Standardization Board Report for the aircraft type) or AFS-400.
c. Aircraft demonstrated to meet airworthiness provisions of previous versions of AC 120-29 through Change 3, or criteria previous to AC 120-29, may remain eligible for previously approved operational authorizations.
Additional airworthiness demonstration under provisions of this AC are not necessary for these aircraft unless additional credit based on meeting appendices of this AC is specifically sought.
d. Operators seeking credit provided for only by this version of AC 120-29A, and that were not available in previous versions of AC 120-29 must meet operational criteria as described in the main body of this AC.
e. New airworthiness approvals addressing Category II, intended for use by an air carrier, may use criteria prior to this AC only on a case by case basis as determined by FAA. Examples of cases where criteria prior to this AC may be acceptable include providing information from a service bulletin based on a previous version of AC 120-29 to ensure compliance status of an “in-service” aircraft. Another situation would be for continuing the production and delivery of an aircraft or autoflight system type which had a type certification basis using a preceding version of this AC, or when seeking certification of a new derivative aircraft which has an autoflight system the same as or very similar to one previously approved based on an earlier version of AC 120-29.
4.3.9. Runway Field Length Requirements and Runway Clutter. For Category I or II, landing distance requirements are as specified by 14 CFR 121.185, 121.187, 121.195 or 121.197.
a. The following typical means of complying with the above provisions of part 121 are considered to be acceptable. Examples are provided for turbine aircraft. Aircraft other than turbine powered aircraft, or aircraft operating under 14 CFR parts other than part 121, may apply equivalent provisions in a similar manner.
b. Part 121 turbine aircraft operations must meet provisions of section 121.195(b). Normally these landing distances (e.g., that already include the specified 60% factor) are factored into the AFM data provided for landing distance. They do not have to be added additionally or separately to the AFM data.
c. If it is determined during dispatch, in weather forecasts or reports, that the landing runway may be wet (e.g., may is considered to include “chance,” “occasional,” “temporary,” or a probability equal to or greater than 10%), the effective runway length must be at least 115% (i.e., IAW section 121.195(d)) of the distance determined under section 121.195(b).
d. Unless otherwise authorized by FAA, wet is considered to be any condition “not clear and dry” on any part of the useable area of the runway (useable area does not include edges, sides, melting of ice or snow banks at edges or sides, area beyond the advertised plowed and sanded surface, overruns, etc.).
NOTE 1: FAA may authorize a wet grooved runway with good braking friction characteristics, or equivalent, to be considered a dry runway for purposes of dispatch determination. A wet runway is considered to be a runway that is other than clear and dry, and has no standing water.
Page 28 Par 4 NOTE 2: Aircraft for which a special demonstration has been made for stopping distance on a wet runway for compliance with section 121.195(d) may use information from this determination for low visibility landing distance assessment (see AC 121.195-1A).
e. If any useable part of the expected landing runway or runways are slippery (e.g., wet and not-grooved or porous friction coarse (PFC), snow, slush, ice, or standing water) the provisions of section 121.195(d) apply. In addition, operators should consider the possible need for extra stopping distance beyond that required by section
121.195(d) if braking action is reported or expected to be worse than “good.” The amount of additional stopping distance, if any is determined by the operator to be appropriate, may be related to any estimated reduction in stopping capability for the assumed conditions.
f. Information on autobrake distance provided by the manufacturer may be used as the basis for Category I or Category II field length determinations. If AFM autobrake data is used as the basis for determining acceptable landing distance, the operator should ensure that appropriate factors for use of autobrakes are considered, and if appropriate, accounted for (e.g., brake configuration, autobrake setting(s), runway surface friction, and runway slope). If a dispatch process applies, dispatch should consider, and provide any necessary information to the flightcrew regarding any pertinent “autobrake settings” on which dispatch may be based. If autobrakes are to be used, it is not necessary to additionally factor autobrake stopping distance data by the 115% specified in section
121.195(d) beyond the stopping distance otherwise protected by section 121.195(d). However, if expected stopping distance based on using an autobrake system, or any particular setting(s) of an autobrake system, is greater than that protected by section 121.195(d), then the operator should take that fact into consideration and provide appropriate stopping distance information or stopping procedures to the flightcrew.
g. When an operator needs to provide for an instrument approach and low visibility landing following an emergency return after takeoff, or when using a takeoff alternate, the operator should consider the expected landing configuration, braking method, and initial braking speeds in assessing landing field length requirements (e.g., consider landing weight, engine out flap settings, engine inoperative speeds as applicable, potential for partial brakes, or partial antiskid, or inoperative reverse thrust).
h. When determining alternate airport field length provisions (e.g., section 121.187 or 121.197 as applicable) it is recommended that the operator consider the weights, flap settings and approach speeds that may be applicable to use of that alternate airport with an engine inoperative. For credit for use of an alternate airport based on “Engine Inoperative Category II” capability, the operator must consider such representative speeds, as applicable to the engine inoperative configuration, in assessment of the required landing distance.
i. The following field length factors and considerations are considered acceptable:
(1) Category I Field Lengths.
(a) For minima or conditions expected to be at or above RVR 3000, the runway field-length requirement for Category I is as specified by section 121.195 for either a dry or wet runway. For minima or conditions expected to be below RVR 3000, the field length requirement should be based on conditions for a wet runway (section 121.195(d)).
(b) Field length requirements are determined based on applicable weather reports and forecasts considered at the time of dispatch or release (i.e., section 121.195 reference to “takeoff”). Once an aircraft is enroute, it is recommended that field length requirements be reassessed if conditions significantly change from the conditions on which the departure was based.
(2) Category II Field Lengths. The Runway Field-Length Requirement for Category II is as specified by section 121.195(d) for a wet runway.
(a) When auto brake systems are used for Category II, information must be available to the flightcrew to assist in making the proper selection of a suitable auto brake setting consistent with the field length available for landing and the runway condition, including braking action.
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(b) Category II operations should not normally be conducted with braking action less than “fair” unless the operator has a method to ensure that timely updates of field conditions are provided to the flightcrew, and, if applicable, also provided to the dispatcher, and that the flightcrew considers that sufficient runway length is available for the landing in the conditions reported.
(3) Runway Field Length Airborne Considerations. Runway field length requirements are typically considered to be dispatch or release (pre-departure) requirements rather than “in-flight” assessment requirements. In the event of unforecast adverse weather enroute, or if braking system or other failures affecting stopping performance occur enroute, the crew should consider any adverse landing distance consequences that may result from a decision to make a landing on a particular runway (e.g., braking action reports, clutter).
4.3.10. NAVAIDs or Landing System Sensors and Aircraft Position Determination.
a. Various landing system sensors (NAVAIDs) or combinations of sensors may be used to provide the necessary position fixing capability to support authorization of Category I or II landing weather minima. While certain navigation sensors (NAVAIDs) are installed and classified primarily based on landing operations, the sensors described in this paragraph may also be used for takeoff, missed approach, or other operations (e.g., RNAV position determination). Regardless of the sensors, NAVAIDs, or combination of NAVAIDs used, the NAVAIDs and sensors must provide coverage for the intended flight path and anticipated displacements from that flight path for normal operations, rare normal operations (e.g., winds and wind gradients), and for specified non-normal operations where applicable (e.g., “VNAV out” flight path, “engine-out go-around” flight path). In addition, Category I or II authorizations should be consistent with the provisions or characteristics for specific sensors listed below in paragraph 4.3.10.1 through paragraph 4.3.10.3 unless otherwise accepted or approved by FAA.
b. For NAVAID-specific procedures (e.g., ILS), use of ICAO recognized NAVAIDs are eligible for authorization as either a Standard Instrument Approach Procedure or as a Special Instrument Approach Procedure.
NAVAID types that are not recognized by or in ICAO criteria (e.g., in Annex 6, Annex 10, ICAO Doc 9365/AN910 Manual of All Weather Operations) are eligible only for authorization as Special Instrument Approach Procedures.
4.3.10.1. Instrument Landing System (ILS). The ILS provides a reference signal aligned with the runway centerline and deviation signals when the airplane is displaced left or right of the extended runway centerline. The linear coverage area for this signal is approximately 3 degrees either side of the extended runway centerline from a point emanating at the far end of the runway. The ILS also provides a vertical flight path (nominally 3 degree descent angle) to a point in the landing zone of the runway. The vertical coverage is approximately 0.7 degrees on either side of the vertical reference path. ILS characteristics should be considered as defined in ICAO Annex 10, unless otherwise specified by FAA. U.S. ILS systems are classified by Type as defined in FAA Order 6750.24 (II/D/2, etc.).
4.3.10.2. Microwave Landing System (MLS). The MLS provides a reference signal aligned with the runway centerline and deviation signals when the airplane is left or right of the extended centerline. The linear coverage area is approximately 40 degrees either side of the extended runway centerline emanating from a point at the far end of the runway. The MLS provides a vertical flight path to the runway similar to ILS. MLS characteristics should be considered as defined in ICAO Annex 10, unless otherwise specified by FAA. U.S. MLS systems are classified by Type, similar to ILS.
4.3.10.3. Global Navigation Satellite System (GNSS) Landing System (GLS). GLS is a landing systems based upon the Global Navigation Satellite System (GNSS). For lowest Category I minima and Category II operations the landing system typically includes a local area differential augmentation system in the vicinity of the runway for which lowest Category I or Category II procedures are specified. The local area system may serve one or more runways, or nearby airports, depending on its classification for each particular runway. The classification of a GLS service may be different for different runway ends (e.g., III/E/3 for Runways 14L and 14R, but I/D/1 for RW 22L).
Desired path, centerline, and deviation signals as applicable, are computed by airborne avionics. The coverage area for GLS is typically within a 30 mile radius of a ground facility, but extended service volumes are possible. GLS
Page 30 Par 4 provides for both vertical and lateral flight path specification to the touchdown zone of the runway(s) served, and a lateral path for rollout or takeoff guidance. GLS characteristics should be considered as defined in ICAO Annex 10, unless otherwise specified by FAA (e.g., FAA-accepted references to RTCA SC-159 MASPS). U.S. GLS systems should typically be classified by “Type” of system for each runway end served, similar to ILS (e.g., GLS II/D/2), or by an equivalent schema. Authorization for use of GLS is for each specific air carrier, aircraft type, and GLS system type until pertinent GLS international standards accepted by FAA are promulgated.
4.3.10.4. Satellite Systems. Navigation Satellite systems currently consist of the U.S. Global Position System (GPS) and the Russian Federation Global Navigation Satellite System (GLONASS). These systems may be considered part of a GNSS.
a. Various forms of augmentation exist or are in development including Space Based Augmentation Systems (SBAS), Ground Based Augmentation Systems (GBAS), and Aircraft Based Augmentation Systems (ABAS).
b. These augmentation systems may also be classified as wide area (e.g., EGNOS, WAAS, MSAS) or local area augmentation systems (e.g., LAAS).
c. GNSS may be combined with certain augmentation systems (e.g., LAAS) to provide a GNSS based Landing System (GLS).
4.3.10.4.1. GPS/GLONASS and Reference Datum Information. Satellite position fixing systems authorized for use by U.S. Operators include GPS and FAA-authorized augmentation systems for use with GPS (e.g., WAAS or LAAS). These systems may be used in the U.S., in U.S. territories, in other States that authorize GPS use, and in international airspace.
a. When using GPS or navigation systems that base position fixing on GPS, it is the responsibility of the operator to ensure that in airspace outside of the U.S. that an appropriate Reference Datum (e.g., WGS-84) is used for definition of waypoint or critical path point coordinates. Information on states using WGS-84 or various other databases are typically available from commercial charting sources, and may be available on the worldwide web.
b. An example of one worldwide web data source for “Datum” information that is acceptable for use is:
http://www.jeppesen.com/qref.html
c. GLONASS, or other satellite position fixing systems than GPS, may be used only as approved by the CHDO/POI following coordination with AFS-400.
4.3.10.4.2. Local Area Systems. Ground Based Augmentation Systems (GBAS) are considered to include the FAA's Local Area Augmentation System (LAAS) and non-federally provided systems (e.g., SCAT I).
a. Initial GLS augmentation authorizations have been limited to use of a DA(H) not lower than 200 ft. HAT.
This value may be reduced as more capable airborne or ground based LAAS equipment is implemented or upgraded, amended criteria are issued, increasing numbers of GLS operational authorizations are issued for a wider variety of operating conditions, and satisfactory operating experience is gained.
b. Procedures based on any form of GBAS augmentation with performance that is equivalent to or better than a U.S. Type I ILS may be identified as “GLS” (GPS Landing System) procedures.
4.3.10.4.3. Wide Area Systems.
a. Space Based Augmentation Systems (SBAS) include the FAA’s wide area augmentation system (WAAS) and other internationally accepted wide area augmentation systems (e.g., EGNOS, MSAS).
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b. Credit for use of SBAS augmentation alone would currently be limited to use of DA (H) not lower than 200 ft. HAT. Procedures based on any form of SBAS augmentation alone or SBAS augmentation in multi-sensor systems such as FMS should be identified as “RNAV” or “RNAV RNP” procedures, as applicable.
4.3.10.5. LOC/LDA/SDF/Back Course. Localizer, Localizer Type Directional Aid (LDA), Simplified Directional Facility (SDF), and Back Course (BC) ILS procedures are authorized for air carrier use and may be authorized to Category I minima not less than 250 ft. HAT.
4.3.10.6. VOR Authorized Procedures. VOR based procedures, when based on VOR alone, when based on multiple VORs, or when specified in conjunction with use of DME, may be authorized to use Category I minima not less than 250 ft. HAT.
a. VOR or VOR/DME based procedures may be flown using any of the following flight instrument displays suitable for the procedure to be accomplished, and for course or intended flight path to be achieved, including:
• EHSI or ND Map Display
• EHSI or ND Raw data display (e.g., EHSI lateral deviation display or VOR needle(s))
• Electromechanical HSI
• RMI, RDMI, or equivalent, or
• raw data lateral deviation display (e.g., cross pointer display)
b. VOR procedures, when flown as a procedure without vertical guidance (e.g., without VNAV), should use an MDA(H).
c. Qualifying VOR procedures, when flown with approved vertical guidance (e.g., with VNAV), may use either an MDA(H) or a DA(H), as determined to be suitable by the operator for the procedure or group of procedures to be flown.
d. The aircraft navigation system or flight instrument system display(s) used should be determined to be acceptable by the POI, for the procedures to be flown, considering that operator’s routes, procedures, crew qualification, training, and recency of experience policies or programs.
e. Use of a Single VOR Airborne System.
(1) Under certain conditions, the use of a Single Airborne VOR system may be acceptable. The objective is for the pilot to have multiple ways of navigating, when operating with a single airborne VOR system such that, in the event of failure of a single element of the airborne navigation or display system, or the NAVAID, the approach can be safely discontinued at any point during the approach to touchdown, or at any time during a missed approach.
(2) Additionally, following initiation of the missed approach or rejected landing, a transition can be made to use some other NAVAID or NAVAIDs, other than the failed system or facility, to complete a safe missed approach and subsequent flight and an approach to an alternate.
NOTE: A period of dead reckoning may be permissible between the time the failure occurs and the time alternate navigation means are established for continuing the missed approach and flight to alternate. During this period of dead reckoning the aircraft should not be unduly exposed to loss of obstacle clearance due to proximity to terrain or significant obstacles. Suitable navigation performance should be achievable to safely complete the missed approach, fly to the alternate, and complete a subsequent approach using a different navigation system or NAVAID, without loss of knowledge of position, loss of appropriate obstacle clearance, or loss of terrain clearance.
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f. Use of RNAV for VOR, VORTAC, or TACAN Fix Substitution. VOR, NDB and TACAN fixes may be authorized for substitution use with “xLS” procedures.
(1) RNAV waypoints or along track fixes may otherwise be substituted for any VOR, TACAN, DME, NDB, Compass Locator, marker beacon, or other fix on any segment of a VOR, VOR/DME, ILS or MLS, LOC, LOC BCRS, or NDB procedure where a corresponding VOR azimuth (radial) or TACAN fix is procedurally specified or can be determined by the FMS to the necessary degree of accuracy and reliability.
(2) The substitution of RNAV capability based on FMS or GPS must be determined to be acceptable for that operator by the CMO or POI.
g. Inoperative or Unsuitable VOR, VORTAC, TACAN, or DME NAVAID. If VOR, VORTAC, TACAN, or DME updating is used in support of area navigation system (e.g., FMS) position determination, Operators and flightcrews should be aware of when and how to disable use of an unsuitable NAVAID or NAVAID element within the navigation system. This is especially true when the unsuitable NAVAID is likely to cause a significant map shift
(e.g., movement of a ground NAVAID to a new geographic location without making a corresponding update to that NAVAID’s recorded position in an aircraft’s navigation system database, thus leading to introduction of a sudden navigation system map display position error).
4.3.10.7. DME. DME based procedures, when used in conjunction with VOR, NDB, LOC, LDA, SDF, or BC are authorized for air carrier use, and may be authorized to Category I minima not less than 250 ft. HAT.
a. When used in conjunction with ILS or MLS, DME along track fixes may be authorized for use with Category I, II, or III procedures, as applicable to the specified procedure.
b. Except for Category II or Category III procedures that are specifically identified by FAA as requiring use of an Inner Marker, DME along track fixes may otherwise be substituted for any marker beacon, VOR, NDB, or Compass Locator on any segment of an ILS or MLS procedure where the corresponding DME value is procedurally specified or can be determined.
c. Use of RNAV for DME Fix Substitution. Suitable RNAV systems including FMS or GPS may be used to substitute for DME when equivalent DME fix information can be established by the flightcrew. For this substitution to be authorized, suitable chart information and flight deck navigation system display information (e.g., electronic navigation map displays) must be available to establish the equivalent DME fix capability required for the areas, airspace, routes, or procedures to be used by the operator. Such substitution may be applicable to normal inflight use, to continuation of flight after failure, or to dispatch with inoperative DME capability if consistent with the applicable MMEL for the aircraft type. The substitution of RNAV capability based on FMS or GPS must be determined to be acceptable for that operator by the CMO or POI.
d. Inoperative or Unsuitable DME NAVAID. If DME updating is used in support of area navigation system (FMS) position determination, Operators and flightcrews should be aware of when and how to disable use of an unsuitable NAVAID or NAVAID element within the navigation system. This is especially true when the unsuitable NAVAID is likely to cause a significant map shift (e.g., movement of a ground NAVAID to a new geographic location without making a corresponding update to that NAVAIDs recorded position in an aircraft’s navigation system database, thus leading to introduction of a sudden navigation system map display position error).
4.3.10.8. NDB Authorized Procedures. NDB based procedures, when based on NDB alone, when based on multiple NDBs, or when specified in conjunction with use of DME are authorized for air carrier use, and may be authorized to minima not less than 300 ft. HAT.
a. NDB or NDB/DME based procedures may be flown using an appropriate EHSI or ND Map Display, EHSI or ND Raw data display, Electromechanical HSI, RMI, RDMI, or ADF display for course guidance, as determined
Par 4 Page 33 acceptable to the POI considering the crew qualification, training, and recency of experience applicable to that operator.
b. NDB procedures, when flown as a procedure without vertical guidance (e.g., without VNAV), use an MDA(H).
c. NDB procedures, when flown as a procedure with approved vertical guidance (e.g., with VNAV), may use a DA(H).
d. Use of a Single NDB/ADF Airborne System. Other than following an in-flight failure of one of several installed airborne systems NDB/ADF receivers, instrument procedures based on NDB/ADF may be flown using a single airborne NDB/ADF receiver in lieu of two airborne NDB/ADF receivers (reference section 121.349) under the following conditions:
(1) The operator is authorized to conduct procedures using a single airborne NDB/ADF receiver;
NOTE: Authorization for use of a single NDB/ADF may be for a specific procedure, a group of procedures, for an operator’s particular fleet of aircraft (e.g., B727 fleet), for all of an operator’s aircraft, or for a geographic region (e.g., within the United States and U.S.
territories), as applicable to the operator’s route structure, and fleet.
(2) Instrument procedures requiring simultaneous use of more than one NDB/ADF NAVAID facility are not authorized, unless approved for that operator and each specific procedure;
(3) In the event of failure of the airborne NDB/ADF receiver, or other essential element of the airborne NDB/ADF navigation or display system, or the NDB/ADF NAVAID, the approach can be safely discontinued at any point during the approach to touchdown, or at any time during a missed approach, and
(4) Following initiation of the missed approach or rejected landing, a transition can be made to use some other NAVAID or NAVAIDs, other than the failed system or facility, to complete a safe missed approach and subsequent flight to an alternate.
NOTE: A period of dead-reckoning may be permissible between the time the NDB/ADF airborne system or NDB/ADF NAVAID failure occurs and the time alternate navigation means are established for continuing the missed approach and flight to alternate. During this period of dead-reckoning the aircraft should not be unduly exposed to loss of obstacle clearance due to proximity to terrain or significant obstacles. Suitable navigation performance should be achievable to safely complete the missed approach, fly to the alternate, and complete a subsequent approach using a different navigation system or NAVAID, without loss of knowledge of position, loss of appropriate obstacle clearance, or loss of terrain clearance.
e. Use of RNAV for NDB Fix Substitution.
(1) Suitable RNAV systems including FMS and GPS may be used to substitute for NDB or ADF when equivalent NDB fix information can be established by the flightcrew. RNAV (FMS) fixes may be authorized for use as an NDB substitute with Category I, II, or III procedures, as applicable. RNAV fixes based on FMS may also be substituted for bearing or cross track fixes. RNAV waypoint or along track fixes may be substituted for any NDB, Compass Locator or other NDB based fix on any segment of a VOR, ILS or MLS, LOC, LOC BC, or NDB procedure where the corresponding NDB bearing is procedurally specified or can be determined by the FMS to the necessary degree of accuracy and reliability.
(2) For substitution to be authorized, suitable chart information and flight deck navigation system display information (e.g., electronic navigation map displays) must be available to establish the equivalent NDB fix
Page 34 Par 4 capability required for the areas, airspace, routes, or procedures to be used by the operator. Such substitution may be applicable to normal inflight use, to continuation of flight after failure, or to dispatch with inoperative ADF capability if consistent with the applicable MMEL for the aircraft type. The substitution of RNAV capability based on FMS or GPS must be determined to be acceptable for that operator by the CMO or POI.
f. Inoperative or Unsuitable NDB NAVAID. If NDB updating is used in support of area navigation system (FMS) position determination, Operators and flightcrews should be aware of when and how to disable use of an unsuitable NAVAID or NAVAID element within the navigation system. This is especially true when the unsuitable NAVAID is likely to cause a significant map shift (e.g., movement of a ground NAVAID to a new geographic location without making a corresponding update to that NAVAID’s recorded position in an aircraft’s navigation system database, thus leading to introduction of a sudden navigation system map display position error).
4.3.10.9. Radar Systems (e.g., PAR, ASR). Various other systems are in limited use (e.g., PAR, ASR). These systems are considered for air carrier operations only as described below.
a. Air carrier approach operations using ASR or PAR may only be approved if OpSpecs contain authority for their use.
b. For use of ASR, dedicated training is not specifically required unless the POI determines that the Operators general training and qualification program is not satisfactory for routine use of ASR procedures, and that specific ASR training is needed.
c. For use of PAR, dedicated PAR training is appropriate unless the POI determines that the Operators training and qualification program is otherwise able to ensure adequate crew preparation so that dedicated PAR/ASR training or demonstration is not needed (also see 4.3.8.8).
4.3.10.10. Other Systems, Procedures, and Special Systems.
a. Marker Beacons. 75 MHz marker beacons are used in the NAS or internationally as part of ILS, and for other limited or special applications (e.g., step-down fixes, departure turn points for instrument departure heading assignments). Use of marker beacons does not require dedicated crew training or qualification beyond that for conduct of ILS approaches.
b. Airborne Radar Approach. Operational authorization of use of any “airborne radar approach” procedure
(e.g., use of ground mapping radar or equivalent) for purposes of conducting an instrument approach requires coordination with AFS-400, and may require proof of concept demonstration acceptable to FAA.
c. KRM, RMS, SRE or other unique systems or procedures which are not necessarily used IAW ICAO criteria
(e.g., as used in certain parts of Europe) may only be approved for use by an air carrier if the aircraft is suitably equipped to receive and use the specified system and the system can meet the performance, integrity, and availability standards equivalent to those established for currently approved types of U.S. operations (e.g., ILS, LDA, ASR, RNAV using FMS). Minima authorized should not be less than any corresponding minima that would be applicable to an equivalent U.S. procedure. If not otherwise an ICAO standard NAVAID, operational authorization of use of such systems should include coordination with the state of the aerodrome and with AFS-400, and may require acceptable review of use or demonstration of use to FAA (e.g., to a POI, APM, or CMO).
d. Transponder Landing System. Transponder Landing System or other such “multi-lateration” systems may only be approved for an air carrier if the system can meet the performance, integrity, and availability standards equivalent to those established for currently approved types of operations (ILS, FMS, etc.), to corresponding minima. Operational authorization of use of any of these systems requires successful completion of a proof of concept demonstration acceptable to FAA.
e. Enhanced Vision Systems are intended to provide the flightcrew with a visual presentation of a view of the approach to a runway that may otherwise be obscured by weather or darkness. Air carrier approach operations using