Par 5 Page 71 operational evaluations are nonetheless appropriate for certain airports having difficult pre-threshold terrain conditions. These special evaluations consider each particular aircraft type, the particular flight control system, and may include consideration of particular system elements such as the type of radar altimeters installed or other equipment. The need for such a special evaluation of a part 97 instrument approach procedure is identified by FAA order 8400.8, Procedures for Approval of Facilities for FAR Part 121 & Part 135 CAT III Operations. Criteria for the evaluation of irregular Pre-threshold terrain airports is contained in FAA Appendix 8 of AC 120-28D. Criteria for approval of Operators or procedures regarding operations at runways with irregular Pre-threshold terrain are addressed in paragraphs 6.2.5 and 10.7.
5.19. Airborne System Evaluation and Approval. Category I and Category II airborne systems may be IAW the applicable airworthiness criteria contained in Appendix 2 or 3 during type certification or STC approval, or they may be evaluated in conjunction with a FAA-approved program with an air carrier. To be acceptable for Category I or II landing minima, the airborne equipment should meet the criteria in Appendix 2 or 3 of this AC and be able to conduct Category I or II operations IAW the operational concepts discussed in Paragraph 4 above. However, if a determination of compliance with Appendix 2 or 3 has not been made, airborne equipment which is shown to meet the operational demonstration criteria in the applicable subparagraphs below may also be acceptable for Category I
(e.g., RNP Operations) or Category II landing minima if it is demonstrated that this equipment permits safe Category I or II operations, as applicable, IAW the operational concepts discussed in Paragraph 4 above.
5.19.1. “Operator Use Suitability” Demonstrations - Applicability. The following criteria in paragraphs 5.19.2 through 5.19.3 (also see paragraph 10.5) apply to applicants desiring airborne equipment approval for those systems which do not have a statement in the approved airplane flight manual which indicates that the equipment meets the relevant performance standards of this AC, previous editions of this AC, or equivalent criteria (e.g., either for Category I such as applicable to FTE demonstrations for RNP, or for Category II). The criteria of paragraphs 5.19.2 and 5.19.3 are not intended to apply to those aircraft types or variants which already include a statement in the approved airplane flight manual indicating that the airborne flight guidance system was evaluated IAW criteria of this AC.
5.19.2. Airborne Equipment Operational Validation. The applicant should provide an acceptable test and evaluation plan which establishes satisfactory performance of the flight guidance system for either the Category I or Category II operations intended, as applicable. To be acceptable, the applicant should conduct an appropriate number of approaches and missed approaches, or other applicable operations, for representative instrument procedures to be flown. For such assessments under this provision, an applicant may be considered to be an operator, a group of Operators, or an aircraft manufacturer or avionics manufacturer in conjunction with one or more Operators. An aircraft manufacturer or avionics manufacturer seeking to demonstrate alternate levels of FTE without involvement of an operator would normally be expected to do so as part of a TC or STC process, IAW criteria of an Appendix of this AC.
5.19.2.1. Category II Assessments. For Category II, the applicant should typically be expected to perform at least 300 successful approaches to appropriate Category II DA(H) minima, in each aircraft type intended. The 300 approaches may be allocated to several variants within a type if the flight guidance systems used by each variant are the same or similar. If a related or similar aircraft type is configured with the same or a similar flight guidance system and is already approved for Category II, or for special case consideration such as consideration of an engine inoperative Category II approach, the number of approaches for a particular type or variant may be reduced by an appropriate amount depending on the degree of system similarity, flight guidance performance similarity, or aircraft similarity, as determined appropriate by the CMO, AEG, or AFS-400. Approaches may be accomplished in line operations, during training flights, or during specific demonstration flights, or in any combination. Not less than ninety percent of the total demonstrated approaches conducted should be successful. No unsafe approaches or missed approaches should occur. (See 5.19.3.3 for a definition of a successful approach). Approaches should be accomplished IAW the following criteria:
a. A minimum of three facilities/runways should be used during the demonstrations, unless Category II operations will be conducted only at fewer than 3 facilities by that operator. At least 10 percent of the total number
Page 72 Par 5 of approaches should be conducted on each of at least three of the facilities selected. The number of approaches conducted on additional facilities may be at the applicant’s discretion.
b. At least some approaches should be accomplished using facilities approved for Category II or Category III Procedures. However, at the applicant’s option, demonstration may be made using facilities used only for Category I Procedures.
c. No more than 15 approaches per day should be conducted on a single facility.
d. No more than 60 percent of the approaches should be conducted in any single aircraft, unless the operator has 3 or fewer aircraft to be evaluated, and performance of the other aircraft may be considered to be equivalent.
e. Where an applicant has different variants of a type aircraft which utilize the same or similar flight guidance system, the applicant should ensure that each of the variants can meet the necessary performance criteria.
f. If flight director performance is to be assessed, a representative number of pilots should be used to conduct the necessary approaches. No single pilot should perform more than 20 percent of the approaches, unless a small total number of pilots assigned to the aircraft type requires the use of a greater percentage.
g. An acceptable sample of the approaches conducted should be observed by an FAA Aviation Safety Inspector or other suitably qualified evaluator(s) (e.g., a check airman representatives of the operator, an APD or equivalent, or representatives from the aircraft or avionics manufacturer), as determined acceptable by FAA.
5.19.2.2. Flight Technical Error (FTE) Assessments. Flight Technical Error (FTE) assessments for approach or missed approach, or other defined operations, may be made by an aircraft manufacturer, an avionics manufacturer, or an operator to establish alternate levels of expected FTE to be used for navigation system or procedure authorization.
Alternate levels of FTE may then be applied to instrument procedure development or authorization, in lieu of standard assumed FTE values, when the assumptions or conditions of the alternate FTE levels can be met or satisfied.
a. FTE levels may be established by analysis (e.g., of existing data), by simulation (e.g., in a suitable flight training simulator), through flight verification (e.g., data collected from flight demonstration(s) with an appropriately configured aircraft), or in any combination of these methods. Regardless of the method(s) used, sufficient assessment should take place to ensure that any resulting FTE information or values are valid for the navigation conditions or procedures to which they are to be applied. The assessment should key to types of procedures to be flown, appropriately consider normal, non-normal and rare normal operations, should address pilot capability or system variability to the extent necessary, and should have sufficient repeatability to have confidence in the FTE level(s) that result.
b. Any FTE assessment related exceptions to industry criteria found in sources such as RTCA DO-236 for RNP should be clearly identified, if necessary (e.g., navigation systems for which 22nm constant radius turns are not intended to be applicable).
5.19.3. Data Collection and Analysis for an Airborne System Evaluation.
5.19.3.1. FTE Data Collection and Analysis. For an FTE assessment demonstration, sufficient data should be collected to establish the suitability of the levels of FTE sought. The data collection and consequent analysis should match and at least consider the types of procedures to be flown (e.g., representative leg types and leg geometry), aircraft configurations to be used (e.g., map display, flight director, autopilot), representative environmental conditions, pertinent normal or non-normal conditions, and representative pilot qualification and experience. Data collection may be from a dedicated FTE assessment, or from data collected during line operations, if appropriate conditions are experienced (e.g., weather) and assumptions satisfied (e.g., pilot sample variability). FTE data collection and analysis may separately address flight on stabilized portions of straight segments, and flight during curved segments or during leg to leg captures. Use of statistical methods for analysis of data is acceptable, but is not
Par 5 Page 73 necessarily required (e.g., for treatment of certain rare normal or non-normal conditions). The analysis methods or techniques to be used by the applicant and any demonstration program to be used should be determined to be acceptable to FAA prior to commencement of the FTE assessment program.
5.19.3.2. Data Collection for a Category II Demonstration. For a Category II system suitability demonstration, each applicant or designated representative should provide the information listed below, as necessary and as requested by the CHDO. This information should be related to performance of the airborne flight guidance system and display system regardless of whether an attempted approach demonstration is successful, unsuccessful, or discontinued. The information, along with recommendations and any clarifying information regarding unsuccessful or discontinued approaches should be provided to the FAA CHDO:
a. Specify the total number of approaches attempted, the number of successful approaches, and the number of and reasons for unsuccessful or discontinued approaches, if known.
b. If an approach is discontinued, specify the height above the runway at which the approach was discontinued.
c. Specify the acceptability of lateral position, vertical position, track, vertical path/vertical speed, speed error, and pitch trim acceptability at 200 ft. HAT, 100 ft. HAT or at DA(H), and note if the approach was in any way inconsistent with continuing an approach to a normal landing within the touchdown zone.
d. Specify the NAVAIDs and runway facilities used and the reported weather and wind conditions in which the assessment was conducted.
e. Evaluate the tracking performance stability, and suitability of the flight director or autopilot, as applicable, for the intended operation.
f. If not otherwise based on data recording, the evaluator(s) should note and record the lateral and vertical position of the airplane relative to the localizer and glide slope at least at the 200 ft. HAT, 100 ft. HAT or at DA(H), and the estimated runway touchdown point achieved consistent with following the flight guidance system, as applicable to the system used.
g. If unable to initiate an approach due to a deficiency in the airborne equipment, note the reason for the deficiency and any recommendation for addressing the deficiency.
h. Provide any other relevant associated recommendations or circumstances.
NOTE: Unsuccessful approaches attributed solely to Air Traffic Service (ATS) circumstances may be excluded from the data (e.g., flights vectored too close to a final fix or at large angles preventing adequate localizer and glide slope capture; termination of an approach at the request of an Air Traffic Facility or due to an amended air traffic clearance;
evidence of inappropriate ILS critical area protection). Also, unsuccessful approaches may be excluded from consideration due to faulty NAVAID or non-aircraft sensor signals.
Airborne system failures attributed to maintenance failures or maintenance factors should be documented for subsequent joint resolution by FAA and the operator.
5.19.3.3. Definition of a Successful Approach for a Category II Demonstration. For the purpose for the airborne system suitability demonstration for Category II, a successful approach is one in which, at least at the 100 ft.
HAT point or DA(H), through touchdown, meets the following criteria:
a. The airplane is continuously in a position to complete a normal landing using normal maneuvering.
Typically this is considered to require that below 200 ft. HAT the flight deck is positioned within and is tracking to remain within, the lateral confines of the extended runway.
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b. The deviation from glide slope does not exceed + 75 microamps (1/2 scale) as displayed on the ILS, MLS, GLS, or equivalent system/indicator at least down to the DA(H). Below the DA(H) a normal approach path is followed and a normal flare occurs, with a landing safely within the touchdown zone at normal sink rates and attitudes.
c. The indicated airspeed, track, vertical speed, alignment, and heading are satisfactory. Indicated air speed does not exceed + 5 knots of planned approach airspeed but may not be less than computed threshold or reference speed.
d. No unusual maneuvers or excessive attitude changes or attitude rates occur.
e. The airplane is generally in trim so as to preclude any excessive control forces.
5.20. Ground Proximity Warning System (GPWS) or Terrain Awareness Warning System (TAWS) Interface. Airborne equipment used for approach should have appropriate interfaces with or compatibility with GPWS and TAWS. This is to ensure nuisance free operation at routine airports. Special procedures may be used for non-normal procedures or at airports with unusually difficult underlying terrain, or other such factors.
5.21. Flight Data Recorder (FDR) Interface. Airborne equipment used for approach should have appropriate interfaces with or compatibility with flight data recorders, and if applicable cockpit voice recorders (e.g., alerting audio audibility on CVR).
5.22. Takeoff, or Dispatch, with Inoperative Navigation Receivers, Instruments, or Displays for Category I or II. Notwithstanding the airborne equipment installation provisions of paragraphs 5.2 and 5.3 above, and IAW any other FAA applicable MMEL and MEL provisions (e.g., as specified by the FAA FOEB or FSB for the type), a pilot may depart or an operator may dispatch an aircraft for Category I or Category II using the following guidelines
(e.g., the operator may address MEL provisions stating “As required by the CFR,” or equivalent provisions, as shown below):
5.22.1. Inoperative System Departure or Dispatch for Category I. For departure, or dispatch for Category I, if applicable, two navigation receivers are typically required, with each suitable for the route of flight and expected approaches to be conducted (e.g., dual ILS, if flying a route based on expected use of ILS for landing).
a. If the flight is based on use of a planned approach procedure that specifically requires dual navigation capability (e.g., /E required, or dual NDB required, or dual VOR required) then two pertinent systems are required for takeoff or dispatch.
b. If an approach procedure planned for use is not precluded from being conducted using one navigation source
(e.g., one NDB, one FMS, one ILS), a minimum of one navigation receiver, or equivalent, of each type required for the intended flight is required. That navigation receiver’s indication, or equivalent, should be able to be displayed at or be visible to each required pilot station, for each type of facility(s) intended for landing. Use of this provision requires considering subsequent failure of the one system intended for use (e.g., the ILS) and the need to be able to safely use any alternate remaining navigation system(s) (e.g., VOR or RNAV) while enroute, during approach, or during missed approach. In any instance, after the first failure in flight, there must still be another suitable navigation capability available to the aircraft to safely land. The other navigation capability required above may be based on use of a different NAVAID type, use of acceptable RNAV capability, or use of an alternate airport with the same or a different type of instrument procedure.
c. Instruments, or displays, or display elements may be inoperative if, considering the remaining instruments or displays, each pilot can accomplish that pilot’s respective assigned crew duties for flying and monitoring the flight
(e.g., failure of an ILS raw data display on the F/O’s ADI or PFD may be permissible if that information or equivalent is available by other acceptable means - such as by using the F/O’s HSI LOC or ND LOC indication in lieu of the ADI LOC indication). When considering inoperative component(s), subsequent failure of any single additional instrument, or display, or display component must not put the aircraft or crew in an unsafe situation for
Par 5 Page 75 which the pilots cannot safely compensate (e.g., it is determined to be acceptable in the above example that after a subsequent failure the F/O will be able to acceptably monitor the Captain’s corresponding instruments, or standby instruments).
5.22.2. Inoperative System Departure or Dispatch For Category II. For departure, or dispatch, for Category II, a minimum of two LOC or GLS navigation receivers of each type to be used are normally required for Category II.
The receiver’s indications to be used should be able to be independently displayed at or be visible to each respective pilot station, for each type of facility(s) intended for landing (e.g., ILS, MLS, or GLS). For ILS glide slope, only one receiver need be operative for departure or dispatch, if that receiver is a self monitored receiver with reliable failure indication, if the receiver information can be displayed at each pilots station, and if any other systems required for the Category II minima do not depend on having dual glideslope capability available (e.g., autoland, alerting and warning or monitoring systems).
a. Use of the “departure or dispatch with a single glideslope receiver” provision requires considering subsequent failure of the one GS system intended for use while enroute or on approach, and the need to be able to safely use alternate remaining navigation system(s) to safely land, after failure of the glideslope receiver in flight.
b. Instruments and displays provisions are the same as for Category I, except that at least one operative radar altimeter must be provided, and that one radar altimeter must at least be able to be displayed at each pilot station, or be easily visible to each pilot station.
NOTE: For Category II minima, if minima are intended to be based on use of an Inner Marker in lieu of a radar altimeter(s), and if the operator is not otherwise precluded from using the Inner Marker as a means to establish Category II minima, the radar altimeter need not be operative for takeoff or dispatch for purposes of establishing landing minima (e.g., for DA(H)). This provision does not address other MMEL/MEL provisions that may otherwise independently apply to radar altimeter availability, however, such as for appropriate GPWS function.
c. In addition to instruments and displays for Category II, there must be acceptable ice and rain removal protection available for the expected conditions during approach (e.g., windshield anti-ice for icing conditions, windshield wipers or equivalent for rain).
5.22.3. Inoperative System Departure or Dispatch for Either Category I or Category II.
a. For departure or dispatch for either Category I or II, for EFIS aircraft that have capability to switch entire display formats to different flight deck display locations, these systems typically may be dispatched with an inoperative display or with displays in alternate locations. For an alternate location, each pilot must be able to acceptably perform respective PF or PNF duties for approach and missed approach. Following failure of an additional display or display in an alternate position, the aircraft must still be able to be safely flown and landed using available instrument approach NAVAID capability and remaining displays.
b. Operators should ensure that planned operations consider any pertinent AFM or FCOM provisions for flight guidance system use that may relate to inoperative components (e.g., altimeter source, navigation source, or instrument source switching, and available flight director or autopilot modes, as applicable).
5.23. Continuation of Flight after Navigation System Failure Enroute, or During Approach for Category I or II.
Notwithstanding the airborne equipment installation provisions of paragraphs 5.2 and 5.3 above, MMEL and MEL provisions of paragraphs 5.22 above, and any other FAA applicable FSB provisions for the type aircraft, a pilot may continue enroute or initiate an approach to Category I or Category II minima using the following guidelines of 5.23.1 through 5.23.3.
5.23.1. Continuation of a Flight After Failures For Category I.
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a. The operator should establish a policy addressing typical failure conditions for which initiation or continuation of an approach in low visibility conditions is considered acceptable (e.g., failure of a single flight director, FCC, or instrument, for which switching to an alternate or common source still provides adequate information). Operators should also describe typical conditions for which the operator would expect that a pilot would divert to a different airport with better weather conditions, if possible (e.g., for complex engine or hydraulic failures where flight guidance or go-around performance may be significantly degraded).
b. Unless dual capability is specifically required for a particular procedure (e.g., /E required, dual NDB required), for initiation or continuation of approach, a minimum of at least one navigation receiver or sensor of each type required for the intended approach procedure is required. If an approach is initiated with only one receiver or sensor, the pilot should, to the extent possible, consider the potential consequence of subsequent failure of that system or sensor.
5.23.2. Continuation of a Flight after Failures For Category II. For continuation enroute or initiation of an approach, a minimum of one LOC or GLS navigation receiver of each type to be used is normally required for initiation or continuation of Category II approach. The receiver’s displacement indications, if applicable, should, however, be able to be independently displayed at or be visible to each respective pilot station, for each type of facility(s) intended for landing (e.g., ILS, MLS, or GLS). For ILS glide slope, only one receiver need be operative for approach if the receiver information can be displayed at each pilot’s station, and if any other systems required for the Category II minima do not depend on having dual glideslope capability available (e.g., autoland, alerting and warning or monitoring systems).
a. Instruments and displays provisions are the same as for Category I, except that at least one operative radar altimeter must be provided, and that one radar altimeter must at least be able to be displayed at each pilot station, or be easily visible to each pilot station.
NOTE: For Category II minima, if minima are intended to be based on use of an Inner Marker in lieu of a radar altimeter(s), and if the aircraft and crew are not otherwise precluded from using the Inner Marker as a means to establish Category II minima, the radar altimeter need not be operative for approach, for purposes of establishing landing minima (e.g., for DA(H)).
b. In addition to suitable instruments and displays, there must be acceptable ice and rain removal protection available for the expected conditions during approach (e.g., windshield anti-ice for icing conditions, windshield wipers or equivalent for rain).
5.23.3. Continuation of a Flight after Failures for either Category I or Category II. If a flight is to be continued to destination and the originally planned instrument approach procedure(s) (IAP) used after a failure enroute, or if an approach is to be continued, the pilot should consider the consequence to and alternatives available for the flight if remaining navigation receiver or sensor capability should subsequently fail.
a. For EFIS aircraft that have capability to switch entire display formats to different flight deck display locations following a failure, these systems typically may be switched to an operative display, or display in an alternate location. For a failed display or an alternate location, each pilot must be able to acceptably perform respective PF or PNF duties for approach and missed approach. Following failure of an additional display or display in an alternate position, the aircraft must still be able to be safely flown and landed using available instrument approach NAVAID capability and remaining displays.
b. Pilots should ensure that planned operations consider any pertinent AFM or FCOM provisions for flight guidance system use that may relate to inoperative components (e.g., altimeter source, navigation source, or instrument source switching, and available flight director or autopilot modes, as applicable).
c. A pilot exercising emergency authority may deviate from the above or any other provisions of this AC to the extent necessary to ensure safe flight and landing.
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6. PROCEDURES.
6.1. Operational Procedures. Appropriate operational procedures based on the approved operator program should be addressed. Operational procedures should consider the pilot qualification and training program, airplane flight manual (AFM), crew coordination, monitoring, appropriate takeoff and landing minima including specification of either a DA(H) or MDA(H), as applicable, for landing, crew call-outs, and assurance of appropriate aircraft configurations. Suitable operational procedures must be implemented by the operator and be used by flightcrews prior to conducting low visibility Category I or II landing operations.
6.1.1. AFM Provisions. The operator’s procedures for low visibility takeoff or Category I or II landing should be consistent with AFM provisions specified during airworthiness demonstrations. Adjustments of AFM procedures consistent with operator requirements are permitted when approved by the POI. Operators should ensure that no adjustments to procedures are made which invalidate the applicability of the original airworthiness demonstration.
6.1.2. Crew Coordination. Appropriate procedures for crew coordination should be established so that each flight crewmember can carry out their assigned responsibilities. Briefings prior to the applicable takeoff or approach should be specified to ensure appropriate and necessary crew communications. Responsibilities and assignment of tasks should be clearly understood by crewmembers. Tasks should be accomplished consistent with the operator’s specified provisions for the aircraft type or variant and each crewmember position unless otherwise approved by the POI (duties of each pilot, monitored approach, etc.).
6.1.3. Monitoring. Operators should establish appropriate monitoring procedures for each type of low visibility approach, landing, and missed approach. Procedures should ensure that adequate crew attention can be devoted to control of aircraft flight path, displacements from intended path, mode annunciations, failure annunciations and warnings, and adherence to minima requirements associated with DA(H) or MDA(H).
a. In the event that a “monitored approach” is used, (e.g., where the first officer is responsible for control of the aircraft flight path by monitoring of the automatic flight system) appropriate procedures should be established for transfer of control to the pilot who will be making the decision for continuation of the landing at or prior to DA(H) or MDA(H).
b. Monitoring procedures should not require a transfer of responsibility or transfer of control at a time that could interfere with safe landing of the aircraft. Procedures for calling out failure conditions should be preestablished, and responsibility for alerting other flight crewmembers to a failure condition should be clearly identified.
6.1.4. Use of the DA(H) and MDA(H). Decision Altitude (Height) is used for Category I and II operations.
Decision Altitude (Height) is used when vertical path guidance is available (e.g., ILS, GLS, MLS, VNAV). Decision Altitude (DA) is used for barometrically determined altitude minima (MSL), typically associated with Category I procedures where vertical guidance is available. If specifically authorized by FAA (rare uses) a DA may in some circumstances be used for Category II.
a. Decision Height (DH) is used for Category II operations, except where use of an Inner Marker is authorized in lieu of a DH, or where a DA is authorized (rare use).
b. When DAs or DHs are specified, procedures for setting various reference bugs in the cockpit should be clearly identified, responsibilities for DA or DH call-outs should be clearly defined, and visual reference requirements necessary at DA or DH should be clearly specified, so that flightcrews are aware of the necessary visual references that must be established by and maintained after passing DA or DH.
c. MDA(H) is typically used for procedures that do not have vertical path guidance (e.g., VOR, NDB, 2D- RNAV, Circling). U.S. Operators are authorized to use MDA. MDH may be used internationally by non-US Operators, and U.S. Operators may need to be aware of its existence and use when operating to international locations even though U.S. Operators are not typically authorized to use MDH. Any request for use of MDH must
Page 78 Par 6 be coordinated with AFS-400. Also the “height element (H)”, used with MDA(H), provides an advisory value for RA relative to the airport or TDZ elevation, and may be used for situation awareness, even if not used to actually define minima. Caution should be noted however, since irregular terrain in the vicinity of the airport may result in observed RA values that are significantly different than expected height (H) derived from the published procedure when not over or near the airport surface.
d. Procedures should be specified for call-out of the DA, DH, or MDA(H).
e. Procedures should be specified for conversion of the DA or DH to an MDA(H) in the event that the aircraft reverts from or loses vertical path guidance. However, any adjustments to approach minima or procedures made on final approach should be completed at a safe altitude (e.g., above 1000 ft. HAT).
f. Any use of QFE procedures for DA or DH for Operators that are not already so authorized (applicable to either Category I or II, whether inside the United States or outside the United States) must be specifically approved by the CHDO, after coordination with AFS-400.
g. For Category II, the operator should ensure that at each runway intended for Category II operations, the radar altimeter systems used to define DH provides consistent, reliable, and appropriate readings for determination of DH.
In the event of irregular terrain underlying the approach path an alternate method should be used. DH may be based on other means (e.g., inner marker) when specifically approved by FAA.
6.1.5. Callouts. Altitude/Height callouts should be developed, implemented, and used for Category I and Category II operations. When more than one Category of operation is used (e.g., Category I or II) callouts should be compatible, consistent, and preferably common to as many Categories of Operation as practicable.
a. Callouts may be accomplished by the flightcrew or may be automatic (e.g., using synthetic voice call-outs or a tone system). Typical call-outs acceptable for Category I or Category II include the following:
• “1000 ft.” above the touchdown zone,
• “500 ft.” above the touchdown zone,
• “approaching minimums,”
• “at minimums,” as applicable,
• any pertinent visual reference(s) observed, and resulting crew action, as applicable (e.g., “runway in sight,... landing”),
• key altitudes during flare, (e.g., 50, 30, 10) or AFGS mode transitions (e.g., flare, rollout), and
• as appropriate, auto spoiler, reverse thrust deployment and autobrake disconnect.
b. Combinations of these calls may also be used as appropriate. In any event, the calls made by the flightcrew should not conflict with the automatic systems or auto call-outs of the aircraft, and conversely the configuration selected for the aircraft should not conflict with expected call-outs to be made by the flightcrew. Compatibility between the automatic call-outs and the crew call-outs must be ensured. The number of call-outs made automatically, manually or in combination should not be so frequent as to interfere with necessary crew communication for abnormal events.
c. Also, call-outs should be specified to address any non-normal configurations, mode switches, failed modes, or other failures that could affect safe flight, continuation of the landing, or the accomplishment of a safe missed approach. Any use of crew initiated call-outs at altitudes below 100 ft. during flare should ensure that the call-outs do not require undue concentration of the non-flying pilot on reading of the radar altimeter rather than monitoring the overall configuration of the aircraft, mode switching, and annunciations. Automatic altitude call-outs or tones are recommended for altitude awareness, at least at and after passing DA(H) or MDA(H).
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6.1.6. Configurations.
a. Operational procedures should accommodate any authorized aircraft configurations that might be required for Category I or Category II approaches or missed approaches. Examples of operational procedures that an operator may need to accommodate include:
(1) Alternate flap settings,
(2) Use of alternate AFGS modes or configurations (e.g., with or without autopilot(s) or flight director(s), autoland, HUD),
(3) Inoperative equipment provisions related to engine(s) inoperative, or the minimum equipment list, such as a non-availability of certain, inoperative instruments (e.g., PFD, radar altimeter), air data computers, hydraulic systems or instrument switching system components,
(4) Availability and use of various electrical system components (e.g., generator(s) inoperative), alternate electrical power sources (e.g., APU) if required as a standby source, and
(5) If applicable, describing the relationship of approach minima to any decision or commit points for critical aircraft configurations that are identified by the operator (e.g., two engines inoperative procedures for three or four engine aircraft, or abnormal flight control configuration procedures)
b. Procedures required to accommodate various aircraft configurations should be readily available to the flightcrew to preclude the inadvertent use of an incorrect procedure or configuration. Acceptable configurations for that operator and aircraft type should be clearly identified so that the crews can easily determine whether the aircraft is or is not in a configuration to initiate a low visibility approach using a pertinent Category I or Category II procedure.
c. Configuration provisions must be consistent with, but are not limited to, those provided in the OpSpecs for that operator.
6.1.7. Compatibility between Category I, Category II, and Category III Procedures.
a. The operator should ensure that to the extent possible, flightcrew and operational procedures for Category I and Category II are consistent with the procedures for that operator for Category III, particularly to minimize confusion about which procedure should be used in variable weather.
b. The operator should to the extent practical, minimize the number of procedures that the crew needs to be familiar with for low visibility operations so that, regardless of the landing category necessary for an approach, the correct procedures can be used consistently and reliably.
6.1.8. Procedure Considerations During Non-Normal Operations. When procedures or configurations have been specified for non-normal situations, flightcrews are expected to apply those procedures and use good judgment in making the determination of any appropriate adjustments to safely use an instrument approach procedure. This may include identifying any necessary adjustments to DA(H), MDA(H), approach path, missed approach path, or required visibility believed to be necessary (e.g., assessing the climb gradient that can be achieved, identifying a safe engine out lateral and vertical flight path, requesting an appropriate length of final approach). Guidelines for nonnormal configurations, situations, or procedures may be provided by the aircraft flight manual or by the operator.
Crews are expected to be familiar with these guidelines and apply them to the extent practical.
a. Specific guidelines for initiation for a Category II approach with an inoperative engine are provided in paragraph 5.17.
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b. When procedures or configurations have not been specified for a non-normal situation or configuration, flightcrews are expected to use good judgment and select the safest course of action in making the determination of appropriate configurations or margins for an approach. The decisions to initiate, continue, or to discontinue an approach, divert to an alternate, and any adjustments to minima should be made considering relevant factors such as:
• Seriousness of the emergency
• Failure status of the aircraft
• Potential for unknown damage or further failures
• Navigation system status
• Runway, visual aid, and NAVAID status
• Procedure flight path and minima to be used
• Proximity to high terrain, obstacles, or adjacent approaching aircraft
• Potential altitude loss, flight path required, or cleanup altitude needed to change configuration and accelerate for a missed approach
• Obstacle clearance during transition to a missed approach (including the possible need to reject the landing from below DA(H) or MDA(H)
• Fuel on board
• Distance and suitability of alternate airports
• Likelihood of changing weather, NAVAID, or runway conditions,
c. It is not the intent of this AC to comprehensively define guidelines for each circumstance that might be possible (e.g., serious in-flight fire, minimum fuel). It should be noted, however, that flightcrews have both the authority and responsibility to consider relevant factors, such as those identified above, when deciding the safest course of action. If doubt exists on a course of action (e.g., initiating or continuing an approach with conditions potentially below minima), it is the flightcrews responsibility to exercise any necessary emergency authority to ensure safe flight.
6.2. Category I or Category II Instrument Approach Procedures.
6.2.1. Acceptable Procedures for Category I. Procedures acceptable for a Category I authorization for a U.S.
Operator in the Unites States, or internationally, under provisions of part 121, 125, or 135, or for a Foreign Operator under provisions of part 129 at U.S. Airports, are those listed in paragraphs 4.3.1.4, 4.3.2, and 4.3.3, and any others found acceptable to FAA and listed in Standard OpSpecs, Part C.
6.2.2. Acceptable Procedures for Category II. Procedures acceptable for a Category II authorization for a U.S.
Operator in the United States, or internationally, under provisions of part 121,125, or 135, or for a Foreign Operator under provisions of part 129 at U.S. Airports, are those listed in Paragraphs 4.3.1.4 and 4.3.2 above, and any others found acceptable to FAA and listed in Standard OpSpecs, Part C.
6.2.3. Standard Obstacle Clearance for Approach and Missed Approach. Standard approach and missed approach criteria for obstacle clearance for normal operations are as specified in FAA Order 8260.3, United States
Par 6 Page 81 Standard for Terminal Instrument Procedures, or as referenced in FAA Air Traffic criteria for terminal procedures (FAA Order 7100.11, Flight Management System Procedures Program), or for non-U.S. airports, ICAO PANS-OPS.
a. Standard VNAV criteria may be applied as specified in FAA Order 8260.40, Flight Management System (FMS) Instrument Procedures Development.
b. Standard RNP criteria may be applied as specified in Appendix 5 of this AC or pertinent paragraphs of AC 120-28D.
c. For non-normal operations (e.g., engine inoperative), criteria equivalent to that specified in 14 CFR for takeoff (e.g., section 121.189) may be applied for those portions of an approach or missed approach not otherwise addressed by procedure design for normal operations (e.g., engine out missed approach gradients, or engine inoperative flap retraction and acceleration segments, or a rejected landing climb back to procedurally protected airspace after loss of visual reference at an airport with significant nearby obstacles or mountainous terrain)
d. Regardless of criteria used, the operator should ensure appropriate consistency between obstacle clearance criteria used for takeoff, en route operations, terminal procedures, instrument approach procedures, engine inoperative procedures, and drift down procedures, as applicable.
6.2.4. Special Obstacle Criteria. Obstacle criteria for RNP is as identified in Appendix 5.
a. Obstacle clearance criteria for Category II procedures is identified in Appendix 6.
b. Obstacle clearance criteria to facilitate implementation of VNAV paths for approaches other than xLS are contained in FAA Order 8400.10
c. Other obstacle clearance criteria may be requested for use by an applicant and authorized by FAA, for specific applications (e.g., international operations, operations at military facilities, disaster relief). When other criteria are used, related compensating factors are typically considered, to ensure equivalent safe terrain or obstacle clearance.
6.2.5. Irregular Pre-threshold Terrain Airports. Irregular pre-threshold terrain airports identified by a 14 CFR part 97 procedure, or by FAA Order 8400.8, must be evaluated IAW FAA approved procedures prior to incorporation in OpSpecs for use by air carriers operating to Category II minima. (See the FAA worldwide web site for Category II/II Status L, for Restricted (irregular pre-threshold terrain) airports:
http://www.faa.gov/avr/afs/afs410/afs410.htm).
Acceptable procedures for evaluation of use of these airports may be found in AC 120-28D, Appendix 8. For aircraft not using autoland, this evaluation consists primarily of ensuring availability of an appropriate method for identification of DA(H) (e.g., assessing acceptable radar altimeter indications approaching and at DA(H), or substituting use of “Inner Marker” in lieu of Radio Altimeter). Assessing acceptable radar altimeter indications is done by ensuring sufficient Radio Altimeter display readout stability and continuity to be able to be easily read the Radar Altimeter when approaching DA(H) and at DA(H), while over-flying the irregular underlying terrain. This assessment may typically be done during operations using minima no lower than Category I, or may be based on operations at that runway by that operator with an equivalent radio altimeter installation (e.g., previously in a B757, for new B767 operations), or may be based on other U.S. Operators who have completed an assessment using the same aircraft type and radio altimeter system combination, or equivalent.
6.2.6. Airport Surface Depiction for Category I or II Operations.
a. Unless otherwise authorized for a particular airport or series of airports, a suitable airport surface depiction should be available to flightcrews for each regular, provisional, or alternate airport or any airport the operator could reasonably expect operations (e.g., section 121.161 ETOPS diversion airports, designated emergency airports), to
Page 82 Par 6 ensure appropriate identification of visual landmarks or lighting to safely accomplish taxing from the gate to the runway and from the runway to the gate. Airport depiction should be on an appropriate scale with suitable detailed information on gate locations, parking locations, holding locations, critical areas, obstacle free zones, taxi way identifications, runway identifications, and any applicable taxiway markings for designated holding spots or holding areas. Standard depictions provided by commercial charting services may be acceptable if they provide sufficient detail to identify suitable routes of taxi to and from the runway and gate positions for departure or arrival.
b. Electronic presentations of airport diagrams are considered an acceptable substitute for paper (hard copy) depictions if acceptable operational provision is made for failure of the electronic device providing the airport depiction, if each necessary flight crewmember can have access to the depiction when needed, and if equivalent scaling, orientation, chart detail, and information content is provided.
6.2.7. Continuing Category I or Category II Approaches in Deteriorating Weather Conditions. The following procedures are considered acceptable in the event that weather conditions are reported to drop below the applicable Category I or II minima after an aircraft has passed the final approach point or final approach fix, as applicable (reference section 121.651).
a. Operations based on a DA(H) may continue to the DA(H) and then land, if the specified visual reference is subsequently established by the pilot no later than the DA(H).
b. Operations based on an MDA(H) may continue to the MDA(H), and then to the point of intercept of the VNAV path to the runway, to the VDP, or equivalent, or to the MAP, as applicable, then land, if the specified visual reference is established by the pilot no later than point at which descent below the MDA(H) commences.
NOTE: For wind constraint applicability on final approach see paragraph 6.2.11.
6.2.8. “Approach Ban” Applicability. Sections 121.651, 125.381, and 135.225 generally require that weather conditions be at or above takeoff minima prior to takeoff, and above landing minima prior to initiating the final segment of an instrument approach. However the applicability of these rules can be different for certain Domestic and International Operations (e.g., pilots authority to initiate “Look-See” Approaches at non-U.S. airports when weather is reported below minima). This paragraph explains and clarifies applicability of weather reporting for takeoff minima, and applicability of the “approach ban” provision related to sections 121.651, 125.381, or 135.225 at U.S. and non-U.S. airports.
a. Accordingly, an instrument approach should not be continued beyond the applicable outer marker, final approach fix, or equivalent position in the final approach segment unless the reported visibility or controlling RVR is above the specified minimum. If no outer marker, final approach fix, or equivalent fix is available, or if such a fix is not used as the point of application of an approach ban when weather is reported below minima, the aircraft should in no case descend below an altitude of 1,000 ft. above the TDZE for the runway of intended landing, unless weather is reported to be at or above minima. Equivalent positions to the outer marker are considered to be, but are not limited to: DME, VOR, non-directional beacon, or other such fixes authorized in the standard instrument approach procedure (SIAP), which are located at a position similar to an outer marker, outer compass locator, or final approach fix. A corresponding surveillance radar fix may also be used as a point of application of an approach ban, in lieu of an outer marker, final approach fix, or such equivalent fix.
b. If, after passing the applicable approach ban fix or point (e.g., outer marker, equivalent fix, or an altitude 1,000 ft. above the TDZ Elevation), and the reported visibility or controlling RVR falls below the specified minimum, the approach may be continued to DA(H) or MDA(H). If suitable visual reference can be established prior to descending below DA(H) or MDA(H), a landing may be completed.
c. Controlling RVR means the reported values of one or more RVR reporting locations (touchdown, midpoint, rollout, or equivalent international locations) used to determine whether operating minima are or are not met. Where RVR is used, the controlling RVR is the touchdown RVR, unless otherwise specified by FAA (e.g., through operations specifications).