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e. SA CAT I. SA CAT I differs from standard CAT I by allowing for reduced runway lighting and RVR requirements while lowering the DA/DH, offset by the use of additional onboard equipment. The SA CAT I approach procedure has a visibility minimum as low as RVR 1400 and a DH as low as 150 feet HAT therefore requiring the use of radio altimeter (RA) minima or approved substitute. Minimum required lighting includes a medium intensity Approach Light System (ALS) with runway alignment indicator lights (RAIL) (MALSR) or better ALS (i.e., ALSF or simplified short ALS with RAIL (SSALR)) and High Intensity Runway Lights (HIRL) on the runway. TDZ and runway CL lights are not required. Refer to Order 8400.13 for additional information on airfield infrastructure requirements (i.e., lighting, power, air traffic control, etc.) if required. A single RVR system in the TDZ is also sufficient. SA CAT I requires less runway lighting, approach lighting, and RVR reporting than would normally be required for approach operations at this low visibility, but requires a higher level of aircraft capability than is normally necessary for a CAT I operation. Operators are approved for this operation by the appropriate OpSpec/management specification (MSpec) or LOA. Single-pilot operations are prohibited from using SA CAT I landing minima.
(1) Visual references required for approved SA CAT I operations are discussed below in subparagraph 3-7i(2).
(2) Future use of navigation signals other than ILS for SA CAT I operations (e.g., GLS) may require further evaluation of signal suitability and airborne system compatibility via approved New Technology Demonstration (NTD).
(3) The following, along with any applicable equipment otherwise specified for CAT I, is the minimum aircraft equipment considered necessary for an authorization for SA CAT I:
(a) Two independent navigation receivers, or equivalent, of each type intended for use.
(b) A radio altimeter is required. Two independent radio altimeters are recommended. A certified substitute for the radio altimeter may be approved in coordination with the Flight Technologies and Procedures Division.
(c) Rain removal equipment for each pilot (e.g., windshield wiper, bleed air, and rain repellant).
(d) A suitable manual or automatic flight guidance system (FGS) certified and maintained to support a DH of 150 feet or lower. This system will contain the following attributes in a manner acceptable to the FAA:
1. Manual FGSs must provide each pilot with course and glide path command guidance to the DH, while simultaneously providing the pilot flying (PF) with a continuous indication of the desired trajectory to the runway TDZ independent of the guidance used for the approach. The guidance system must also provide the PF with dynamic perception of aircraft position relative to the TDZ of the runway of intended landing in order to facilitate the transition to the visual segment of the approach by reducing the time needed for the acquisition of visual cues. An aircraft type and/or system previously approved for SA CAT I, based upon HUD equipment, is considered to meet the requirements of this paragraph.
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2. Automatic FGSs certified for CAT II per AC 20-191 and operated and maintained in accordance with the provisions of this AC for CAT II may be authorized. The approved automatic FGS may not be used below 100 feet HAT for this operation, unless otherwise authorized by the Flight Technologies and Procedures Division. This type of authorization requires coordination with the Flight Technologies and Procedures Division and may require further evaluation via an approved NTD.
f. SA CAT II.
(1) SA CAT II differs from standard CAT II primarily by decreased runway and approach lighting requirements (i.e., TDZ lighting and runway centerline lights not required). A MALSR or a SSALR can be substituted for (normally required) ALS with Sequenced Flashing Lights (ALSF-1/2). HIRLs are still required for SA CAT II operations. Refer to Order 8400.13 for additional information on airfield infrastructure requirements (e.g., lighting, power, air traffic, etc.) if required. Operators must be authorized for SA CAT II operations via OpSpec/MSpec/LOA paragraph C060 and must use aircraft currently operationally approved for autoland or HUD with guidance to touchdown capability. Operators who are authorized to conduct SA CAT II ILS approaches may also continue CAT II operations at runways with standard CAT II/III lighting and a CAT II minimum when TDZ and/or runway centerline lights fail as long as the authorized operator uses autoland or HUD to touchdown. Instrument approach operations may be authorized CAT II minima not less than 100 feet DA/DH. See Table 3-2 for associated approach RVR minima.
(2) The future use of navigation signals other than ILS or vision guidance equipage for SA CAT II operations (e.g., GLS) may require further evaluation of signal suitability and independent airborne system position validation via approved NTD.
(3) SA CAT II operations require the use of an automatic flight control system or a manual FGS designed to meet CAT III criteria of AC 20-191.
(4) An aircraft type and/or system previously approved for CAT III using AC 120-28 or equivalent criteria is considered to meet the requirements of this AC for SA CAT II approval.
g. CAT II Using RVR 1000 Minima. CAT II using RVR 1000 minima may be authorized when meeting provisions of standard OpSpec, MSpec, or LOA paragraph C060 (see Appendix 3). Only those operators with an authorized OpSpec, MSpec, or LOA for CAT II operations using aircraft that are currently certified and maintained for CAT III operations
(i.e., autoland or HUD certified to touchdown capability) may be considered eligible for these operations. The OpSpec, MSpec, or LOA must include the limitation requiring the use of autoland or HUD to touchdown as a condition of the minimum. See Table 3-2 for associated approach RVR minima.
Par 3-7 Page 19 TABLE 3-2. SPECIAL AUTHORIZATION CATEGORY II AND CATEGORY II
MINIMA MATRIX CAT II Authorization DH Approach/Landing System TDZ RVR Autopilot HUD FP HUD Autoland OUSD 100’ 1600 Standard 100’ 1200 100’ N/A 1000 SA CAT II 100’ N/A 1200 N/A = Operation not authorized FP HUD = Fail Passive Cat III certified Head-Up Display
h. Application of a DA/DH or Equivalent (e.g., IM), for CAT II. Procedures using CAT II minima typically use a radio altimeter and the associated DH (of the specified DA/DH) for minima determination.
(1) For CAT II, a DH of a published DA/DH, or an equivalent IM, is used as the applicable descent minima. Any “altitude” value specified is considered to be advisory. The altitude value is available for cross reference and backup. Use of the barometrically referenced DA element of a published DA/DH is not currently authorized for part 121, 129, or 135 operations at U.S. facilities.
(2) Procedures that have “Radio Altitude Not Authorized (RA NA)” (e.g., due to irregular underlying terrain) typically use the first indication of arrival at the IM as a means to establish DA/DH. In this instance, both radio altitude and barometric altitude are advisory.
However, an operator may elect to use first indication of arrival at either the IM or the barometric altitude DA, whichever comes first, as the means for minima determination. In this case, barometric altitude may be an acceptable means to establish DA/DH, but only if it occurs before arriving at the IM.
i. Visual Reference Requirements.
(1) For SA CAT I operations, the required visual references are those provisions listed in § 91.175(c) and (d).
(2) For all other instrument approach operations below RVR 1800, § 91.189 and Standard OpSpecs or MSpecs specify the required visual references to continue the approach.
(3) For SA CAT II operations, note that the ground lighting system configuration may be non-standard. Refer to subparagraph 3-7f for further detail.
(4) The reference to Visual Glide Slope Indicator (VGSI) in § 91.175 includes the use of Visual Approach Slope Indicators (VASI), precision approach path indicators (PAPI), Pulsating Visual Approach Slope Indicators (PVASI), or tri-color VASIs.
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(5) Section 91.176 contains the requirements pertaining to visibility and visual reference when operations are based on using EFVS.
j. Precision Approach Radar (PAR). PAR minima may be authorized via OpSpec to minima of not less than 100 feet HAT, or the published minima, whichever is higher. PAR authorizations are limited to those operators and crews specifically qualified to use PAR.
3-8. REQUIREMENTS FOR OPERATIONS BELOW RVR 1000.
a. General CAT III Requirements. The following requirements apply to the operational authorization of CAT III IAPs:
(1) The airborne system should meet the applicable requirements of Chapter 3 and AC 20-191,
(2) Flightcrew qualification consistent with provisions of Chapter 5 for CAT III has been completed,
(3) Appropriate NAVAIDs and airport/lighting facilities for the procedures to be flown, consistent with Chapter 6, should be available,
(4) An acceptable continuing airworthiness/maintenance program for the airborne system provided in accordance with Chapter 7, and
(5) An operational authorization has been completed per Chapter 8 for a U.S. operator or Chapter 9 for a non-U.S. operator.
b. Concepts and Objectives. CAT III minima were formerly classified as CAT IIIa, CAT IIIb, and CAT IIIc. Title 14 CFR part 1 no longer contains definitions of these classifications. CAT III landing minima are now based on and often described in terms of a three-legged stool (i.e., aircraft approach and landing system capabilities, crew qualification, and approach system classification). For example, for a crew authorized for minima as low as RVR 300, if either the aircraft or approach is limited to RVR 600, then the lowest actual minima is limited to RVR 600, which is the highest value of the three legs. Visual conditions encountered in CAT III operations range from visual references being adequate for manual control during rollout to visual references being inadequate even for taxi operations without special visual reference enhancements or suitable synthetic references. Failure effects and system capabilities after failure are associated with different levels of visual conditions (ceiling and visibility) to derive landing minima (AH, DH, and RVR).
(1) Aircraft having statements in the FAA-approved AFM indicating approval for certain CAT III operations (e.g., formerly CAT IIIa operations) are considered to continue to meet the requirements of this AC. Determination of equivalence between previous CAT IIIa, IIIb, and IIIc classifications and CAT III description in terms of failure effects and system capabilities are described below.
(2) CAT III operations may be conducted manually using approved FGSs, automatically using approved autoland systems, or with hybrid systems that employ both
Par 3-8 Page 21 automatic and flight guidance elements. If the particular FGS depicts F/D or other command guidance, it may be approved in accordance with AC 20-191 or equivalent. Additionally, other FGSs may be used if the NTD is satisfactorily demonstrated. When an automatic system is to be the primary means of control, the use of that system should not require pilot intervention. A means for crew intervention must be provided in the event the pilot detects inadequate system performance (e.g., the pilot determines that an automatic landing cannot be accomplished within the TDZ). If a hybrid system is employed, then the primary mode of operation must be automatic to touchdown, with manual control used as an alternate means to complete the operation.
(3) To be approved for CAT III operations, the airplane and its associated systems should be shown to be capable of safely completing an approach, touchdown, and rollout and permitting a safe go-around from any altitude to touchdown following any failure condition not shown to be extremely improbable. A single system failure should not cause total loss of CAT III capability. A combination of failures may cause a loss of CAT III but must not prevent a safe go-around.
(4) Flight deck design, instrumentation, annunciations, and warning systems should be adequate in combination to ensure the pilot(s) can verify the aircraft should touch down within the TDZ and safely rollout when the controlling visibility is reported at or above applicable minima. Concepts other than those currently authorized may be acceptable if NTD testing can demonstrate an equivalent or greater level of safety as presently specified for approval of automatic systems (e.g., hybrid systems or vision enhancement systems).
(5) To be approved for CAT III operations, the airplane and its associated systems should be shown to be able to perform to the necessary level of accuracy, integrity, and availability. This is typically shown initially by the manufacturer during airworthiness demonstration, confirmed during the operational authorization process, and is monitored by the operator on a continuing basis.
(6) CAT III operations are predicated on meeting requirements for CAT II, or equivalent, for that portion of the approach to 100 feet HAT.
(7) The provisions of this AC, or any version of the former AC 120-28 for aircraft previously certified, are considered to be the applicable criteria to assure the necessary performance from flare to landing and rollout.
c. Fail Operational (FO) CAT III Systems. An FO system is a system that, after failure of any single component, is capable of completing an approach, flare, and touchdown, or approach, flare, touchdown, and rollout by using the remaining operating elements of the FO system. The failure effects of single components of the system, airplane, or equipment external to the airplane that could have an effect on touchdown or rollout performance must be considered when evaluating FO systems. FO systems may be used to touchdown with or without a rollout system. Use of an FO system to touchdown in conjunction with a rollout system that is not FO is acceptable as long as suitable minimum RVR values are specified in the OpSpecs.
(1) As of the publication of this AC, the lowest authorized minima for U.S. operators are touchdown, mid, and rollout RVR 300.
Par 3-8 Page 22 NOTE: A landing system is considered to include each of the elements in the aircraft that are necessary to perform the landing and rollout function
(e.g., flight control, hydraulic system(s), electrical system(s), and sensors).
(2) The reliability and performance of the required operational systems should be such that continued safe operation to landing, or landing and rollout, can be achieved following any failure condition occurring below the AH that is not shown to be extremely improbable. Systems identified below and in AC 20-191 or equivalent are considered to meet the intent of this provision.
(3) The redundancy required for approval of an FO CAT III aircraft may be provided by multiple automatic landing systems, multiple automatic landing and rollout systems, redundant manual FGSs, or suitably redundant approved hybrid systems (NTD).
(4) Failure conditions that result in the loss or disconnect of all the redundant landing or landing and rollout systems, occurring below the AH, are permissible if the occurrence of these failure conditions is extremely remote and the loss or disconnect is accompanied by acceptable warning indications for the pilots. Airplanes that are demonstrated to meet the airworthiness assessments of AC 20-191 for FO systems are considered to meet these reliability and performance criteria.
(5) The following are typical arrangements that may be acceptable for FO systems:
(a) Two or more monitored fail passive (FP) autopilots or integrated autopilot F/D systems, each with dual channels making up an automatic FO system designed so that at least one autoflight system remains operative after the failure of one system, and the failed system is not used or cannot cause unacceptable autoflight system performance.
NOTE: Following a failure with this configuration, it is not intended that a landing be continued with F/D alone, unless a successful NTD has been completed.
(b) Three autopilots or integrated autopilot F/D systems designed so that at least two remain operative after failure to permit comparison and provide necessary monitoring and protection while continuing to a landing.
(c) A monitored FP automatic flight control system with automatic landing capability to touchdown and rollout, if applicable, plus an independent and adequately failure-protected manual FGS, suitable for landing and rollout with guidance provided for the PF and monitoring displays for the pilot monitoring (PM). An NTD may be necessary for this arrangement.
(d) Two independent and adequately monitored manual FGSs with independent displays for the PF and the PM, each capable of supporting a landing and rollout. An NTD would be necessary for this arrangement.
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(6) Aircraft meeting FO requirements of AC 20-191, or equivalent, for landing and rollout may be authorized for FO CAT III to the lowest currently applicable minima specified in OpSpecs for this type of system.
(7) Aircraft previously demonstrated to meet acceptable FO criteria may receive additional credit beyond those already authorized, as specified in provisions of this AC, through proof of compliance with applicable operational provisions of this AC and any subsequent amendment of applicable OpSpecs.
(8) Aircraft with an FO landing system, but without a rollout system, that were originally approved in accordance with previous versions of AC 120-28 may typically be approved for minima not less than TDZ and mid RVR 600. Eligibility for RVR 600 requires compliance with appropriate current Service Bulletins (SB) in accordance with the manufacturer’s recommendations, and a determination by FAA that “in-service” operational performance of the system is acceptable.
(9) Aircraft originally approved in accordance with FAA “Special Conditions” for a rollout system, or criteria of versions of AC 120-28, are considered to have rollout capability equivalent to FO for minima not less than TDZ, mid, and rollout RVR 300. For these aircraft, appropriate current SB compliance should be reviewed and completed, and line operational performance of the system must be shown to be acceptable. However, it is important to note that, as with other aircraft types, CAT III authorization for some of these aircraft may be restricted to certain runway facilities since landing or rollout performance may not necessarily be acceptable due to site-specific irregular underlying approach terrain, TDZ slope, or ILS beam characteristics.
d. Alert Height.
(1) FO CAT III is based on use of an AH. The AH is the height above a runway based on characteristics of the airplane and its FO system, above which a CAT III approach must be discontinued and a missed approach initiated if a failure occurs in one of the redundant parts of the flight control or related aircraft systems, or if a failure occurs in any one of the relevant ground systems. The AH design philosophy requires an aircraft be capable of safely completing a touchdown and rollout (if applicable) following a single failure occurring in the systems noted above, below the specified AH.
(2) Operational AHs must always be equal to or lower than that specified in the airworthiness demonstration, and may be specified at or below 200 feet HAT. The AH is specified by an operator of an aircraft and approved by the FAA. The operational AH used must be consistent with the aircraft design, training, ground facilities, and other factors pertinent to the air carrier’s operation. Typically, a minimum usable operational AH is 50 feet HAT. Lower AHs may be approved if there is an appropriate reason to do so (e.g., for certain types of hybrid systems).
(3) Airworthiness demonstration of an AH is specified in AC 20-191. To ensure the necessary reliability of aircraft systems, airworthiness demonstrations of AH should be from an altitude of at least 200 feet above the TDZ elevation.
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e. Fail Passive CAT III Systems.
(1) A fail passive system is a system that, in the event of a failure, causes no significant deviation of aircraft flightpath or attitude. The capability to continue the operation may be lost and an alternate course of action (e.g., a missed approach) may be required. An FP system is the minimum acceptable system for CAT III operation with a DH.
(2) FP approach operations meeting provisions of AC 120-28, AC 20-191, or equivalent, are typically conducted with a DH not lower than 50 feet, and are limited to RVR values that provide suitable visual reference to address normal operations as well as failure contingencies. Authorization of DH less than 50 feet HAT may require NTD.
(3) An FP CAT III system does not provide sufficient redundancy to successfully continue the approach and landing to touchdown following any failure in the flight control system not shown to be extremely remote. Therefore, a DH is specified in this instance. In the event of a failure of the airborne system at any point in the approach to touchdown, a missed approach is required. However, this provision does not preclude a pilot’s authority to continue an approach if continuation of an approach is considered by the pilot to be a safer course of action.
(4) Such a failure, however, does not preclude continuation to CAT I or CAT II minima if the necessary remaining elements of the aircraft system are operational and if the flightcrew qualification addresses necessary action to continue such an approach is met. Any adjustments to approach minima or procedures made on final approach should be completed at a safe altitude.
(5) An aircraft using an FP system for CAT III should be shown to provide the capability to touchdown in the TDZ or to complete a safe manual or automatic go-around. This capability should be demonstrated from any altitude to touchdown following any failure condition not shown to be extremely improbable.
(6) Typical arrangements that may be used to meet the requirements for CAT III FP operations using a 50 feet DH include the following:
(a) A single monitored automatic flight control system with automatic landing capability.
(b) An FO automatic flight control system with automatic landing that has reverted to an FP configuration or has been dispatched in an FP configuration. This provision is in place for dispatch and prior to initiating the approach. It is not intended to allow switching to an FP configuration if a FO system degrades during the approach. In that event, a missed approach should be initiated.
(c) An FGS designed for manual control by the PF (e.g., FP HUD), and for monitoring by the PM. Aircraft intended for FP CAT III operations should have aircraft systems that meet the criteria specified in AC 20-191. Aircraft previously demonstrated to meet earlier FP criteria may continue to operate using CAT III minima in accordance with approved OpSpecs.
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f. Decision Height.
(1) For CAT II and certain CAT III procedures (e.g., when using an FP landing system), a DH (or an approved equivalent) is used as the controlling minima. The “Altitude” value specified is considered as advisory and is available for cross reference. Use of a barometrically referenced DA for CAT III is not currently authorized.
(2) A DH is applied to all FP operations and is specified at certain international locations where FO minima are authorized. For CAT III, a DH is a specified radio altitude above terrain on the final approach or TDZ. The DH is established to ensure that prior to passing that point the pilot is able to determine that adequate visual reference exists to allow verification that the aircraft should touch down in the TDZ.
g. CAT III Operations with Not Lower than RVR 700 Landing Minima.
(1) Operations with landing minima of not lower than RVR 700 may be conducted with a FO or FP landing system, with or without a rollout control system (See Table 3-3, Lowest Minima Currently Authorized for Fail Operational or Fail Passive Landing Systems, or Landing and Rollout Systems, for specific minima). Previous testing and harmonization efforts led to lowering CAT IIIa minima to RVR 600; however, CAT III operations with RVR 700 minima are the lowest suitable for use on navigation facilities that support guidance for positioning through touchdown but do not support unmonitored rollout guidance. Some facilities and/or legacy aircraft are limited to RVR 700 based upon approach classification or aircraft certification. See subparagraph 3-8i, CAT III Operations RVR Minima Rationale, below for further discussion.
These operations were formerly defined as CAT IIIa in the CFR and FAA documents. They may still be defined as CAT IIIa in ICAO annexes and foreign documents.
NOTE: Some FAA instrument procedures may still retain CAT IIIa nomenclature until these procedures are updated or amended.
NOTE: Reported TDZ and mid RVR must meet the approach chart minima to conduct any CAT III operation. The reported rollout RVR, while still controlling, may be lower than charted minima, if authorized via OpSpec.
(2) Operations using an FO system without an operational rollout control system require the use of a DH to ensure suitable visual reference of the TDZ.
(3) For FO systems, there should be a sufficient combination of information from flight instruments, annunciations, and alerting systems to ensure the pilot can verify that the aircraft should touch down within the TDZ, and safely initiate rollout.
(4) Aircraft demonstrated to meet the airworthiness provisions of AC 120-28 for FP systems remain eligible for any previously approved operational authorization under provisions of this AC and do not require additional airworthiness demonstration. Aircraft previously having completed an airworthiness demonstration in accordance with AC 120-28 remain eligible for any operational authorization that was permitted by AC 120-28.
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(5) Aircraft demonstrated to meet airworthiness criteria prior to AC 120-28B, and not currently authorized in OpSpecs for CAT III, may be approved for new FP CAT III operations on a case-by-case basis depending on facilities to be used, SB compliance status, and other relevant safety factors.
(6) Aircraft that were authorized for FO CAT III, but have not been demonstrated to meet the provisions for FP systems shown in previous versions of AC 120-28 or AC 20-191, may be approved for FP operations with landing minima limited to RVR 1000 provided the following criteria are met:
(a) The aircraft must be shown to be in compliance with relevant SBs for the applicable flight control system and displays.
(b) An auto throttle system must be installed and operational.
(c) The system must be shown to provide reliable autoland performance in line operations.
(d) A demonstration using an appropriately approved full flight simulator (FFS) or aircraft must be completed for that operator and aircraft type, showing that the system and procedures applicable to FP operations can be practically applied for that air carrier’s operation.
(7) Aircraft not previously authorized or not currently authorized by the FAA to use minima less than RVR 1000 based on a FP system must meet the airworthiness requirements of AC 20-191 or equivalent for any new authorization of minima less than RVR 1000.
(8) New aircraft types or derivative aircraft with new flight control system designs should be demonstrated in accordance with AC 20-191 for FP systems, or equivalent requirements, if FP authorization is sought.
h. CAT III Operations with Landing Minima RVR 600 or Less.
(1) CAT III operations with landing minima of RVR 600 or less are usually conducted with FO systems. These operations were formerly defined as CAT IIIb in the CFR and FAA documents, and may still be defined as CAT IIIb in some ICAO annexes and foreign documents.
(2) Airborne systems authorized for landing at or below mid RVR 600 must include a rollout system. Either a manual FGS or an automatic rollout or control system for lateral steering may be acceptable. Either system must provide the means to control the aircraft until the aircraft slows to a safe taxi speed. Operations based on FO systems require the use of systems that, after passing AH, are capable of the safe completion of the approach, touchdown, and rollout, following any failure conditions not shown to be extremely remote. When FO systems are used, they do not require operating procedures which specify that the approach must be continued after a failure.
(3) Operations based on FO systems with an approved rollout system are generally conducted to an AH. The availability of visual reference is not a specific requirement for continuation of an approach to touchdown. The design of flight instrument systems,
Par 3-8 Page 27 annunciations, and alerting systems should be adequate to ensure the pilot can verify the aircraft should touch down within the TDZ and rollout.
(4) Operations may be conducted to a TDZ RVR of not less than 600 and a mid RVR not less than 400 with an FO or FP landing system and with any FAA-approved rollout control system.
(5) Operations may be conducted to a TDZ and mid RVR not less than 400 when using an FO landing system and a rollout control system shown to meet FP criteria of AC 20-191 (or earlier FAA criteria applicable to a rollout system).
(6) In all cases above, operations may be conducted with a rollout RVR as low as 300.
(7) Irrespective of CAT III definitions and certification standards which may reference lower RVR minima, as of the publication of this AC, the lowest authorized minima for U.S.
operators are touchdown, mid, and rollout RVR 300. A summary of the minima that may now be authorized based on the above criteria are shown below in Table 3-3.
(8) See note below for criteria, and subparagraph 3-8c above for examples of various aircraft types, systems, and minima that may be authorized.
NOTE: AC 120-28D Appendix 3 amended criteria for FO rollout control systems. As a result, certain systems previously certificated using the criteria of AC 120-28B or 120-28C, which were not considered FO due to conditions noted in the AFM as exceptions, were considered under AC 120-28D to meet FO criteria.
i. CAT III Operations RVR Minima Rationale.
(1) The concept of CAT III approach requires no visual segment. However, TDZ RVR values must be sufficient such that adequate visual reference exists to allow verification that the aircraft should touch down in the TDZ when using FP landing systems. The TDZ RVR values shown in Table 3-3 for FP systems are not sufficient for an unguided, visual landing, but are only sufficient for the pilot to verify aircraft position to land when arriving at DH. TDZ RVR values must also be adequate for initial pilot control of rollout after touchdown either without a rollout system or in case of FP rollout system failure.
(2) Mid RVR reports must be sufficient to allow pilot visual confirmation of rollout guidance system performance and also be sufficient to support safe, unguided, manual control during the high speed rollout segment in case of FP system failure.
(3) Minimum rollout RVR in all cases must support low speed (40 knots or less) rollout and taxi operations. For aircraft or operator procedures known to require the maximum allowable rollout distance and commensurate higher speed in the rollout RVR area, a higher required RVR report may be necessary.
(4) RVR 600 is the lowest RVR that provides visual cues necessary in verifying that the aircraft should touchdown in the TDZ using a 50 foot DH or during unguided rollout. RVR 600
Par 3-8 Page 28 is therefore the minimum required for landing operations using a 50 foot DH (i.e., with FP landing systems) and high speed rollout in the mid RVR area without a rollout system. Lower RVR values and associated DH using hybrid systems may be acceptable upon completion of NTD testing. RVR 400 is the minimum visibility necessary to confirm proper rollout system operation or for control in case of rollout system failure. Therefore, RVR 400 is the lowest visibility assigned for FP system controlled rollout in the mid RVR area. RVR 400 is also necessary for an FO landing system if the rollout system is FP. RVR 300 is the lowest visibility used for operations with FO landing and rollout systems. While visual references for touchdown or rollout are not required for FO systems, RVR 300 is used for all FO CAT III operations as a practicable minimum value for final, low speed rollout to runway turnoff. RVR 300 is also accepted as the lowest generally useable minimum for safe ground operations using natural vision. Lower RVR values for FO systems may be achievable through the use of advanced vision or sensor systems upon successful completion of an NTD.
(5) A summary of the minima that may now be authorized based on the above criteria are shown below in Table 3-3.
TABLE 3-3. LOWEST MINIMA CURRENTLY AUTHORIZED FOR FAIL
OPERATIONAL OR FAIL PASSIVE LANDING SYSTEMS, OR LANDING AND
ROLLOUT SYSTEMS Landing System Type Rollout System Type TDZ RVR Mid RVR Rollout RVR FP or FO None 600 (175m) 600 (175m) 300 (75m) FP FP or FO 600 (175m) 400 (125m) 300 (75m) FO FP 400 (125m) 400 (125m) 300 (75m) FO FO 300 (75m) 300 (75m) 300 (75m)
NOTE: “Relevant” or “applicable” mid or rollout RVR is considered to be any RVR sensor report (or equivalent instrumentally derived RVR measurement) considered to be covering a portion of the runway where the aircraft is operating at a speed above a safe taxi speed (See subparagraph 6-4b).
j. Previously Approved CAT I/II/III Operations or Use of Previous or New CAT I/II/III Criteria. Operators approved in accordance with AC 120-29 or AC 120-28 may continue to operate in accordance with their previously approved program, consistent with current standard OpSpecs or any special provisions approved for that operator in that operator’s approved OpSpecs.
(1) Approval criteria used for a particular aircraft are typically listed in an AFM. If not shown in an AFM, the applicable FAA Aircraft Evaluation Division may be consulted through the POI or certificate management office (CMO) to determine eligibility.