AC 120-29 CHG 1 Appendix 1 15 Dec 71 Page 5
(5) The glide slope receiving equipment should be adjusted in accordance with RICA Paper 23-63/DO-117, dated 14 March 1963, "Standard Adjustment Criteria for Airborne Localizer and Glide Slope Receivers."
* When deviating from the present 19 foot criteria in antenna location when the aircraft is flown either manually or utilizing an approved automatic landing system the following conditions must be met:
The vertical distance between the glide slope antenna and the main landing gear wheels shall not be greater than that which will result in a nominal height of wheels over threshold of 20 feet when the aircraft is flown at a recommended operationally acceptable landing weight along a glide path meeting the 50 foot + 10/- 3 threshold crossing When all tolerances are considered in reasonable probable combinations, the aircraft shall not be placed in a position where the wheels cross less than 10 feet over the threshold.
This analysis must consider meteorological effects and include reasonable values of windshear.
(c) The analysis must show that adequate safety margin is provided when the airplane is flown manually through the approach and landing and, if appropriate, along a path similar to that used by the automatic system and for manual landings resulting from takeover at any point during an * C. Automatic Pilot/Coupler. When an automatic pilot/coupler system is used as part of a Category Il installation, it should, in addition to complying with applicable ISO and FAR/advisory circular material, provide the following performance under the test condition stated:
(1) Airplane Speed - Maximum and minimum design approach speeds.
(2) Wind Conditions (the effects may be shown analytically) - Surface downwind component of 10 knots. Windshear of 4 knots per 100 feet altitude applied along the runway or across the runway individually, commencing at an altitude of 500 feet.
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Appendix 1 AC 120-29 CHG 1 Page 6 15 Dec 71
(3) Localizer Performance - "* орно поти іони прово". The airplane should be stabilized on the localizer for the purpose of demonstration before the outer marker is inter- From the outer marker to an altitude of 300 feet above runway elevation on the approach path, the automatic pilot/coupler should cause the airplane to track automatically to within † 35 microamperes (95 percent probability) of the indicated localizer course.
performance should be free of sustained oscillations.
(c) From an altitude 300 feet above runway elevation on the approach path to the decision altitude (100 feet), the automatic pilot/coupler should cause the airplane to track automatically to within + 25 microamperes (95 percent probability) of the indicated course. The performance should be free of sustained oscillations.
(4) Glide Slope Performance -
(a) So tet die the that (a) For the purposes of the demonstration, the airplane should be stabilized on the glide slope before an altitude of 700 feet above the field level is reached.
(b) From 700 feet altitude to the decision altitude the autopilot/coupler should cause the airplane to track the center of the indicated glide slope to within ‡ 35 microamperes or † 12 feet, whichever is the larger, without sustained oscillations.
NOTE: The criteria applicable to manual approaches should be applied when approving autopilots with force wheel steering.
d. Flight Director Systems. When Category II operations are predicated on two independent flight directors the installation should provide for the following performance under the test condition stated:
(1) Airplane Speed - Maximum and minimum design approach speeds.
(2) Wind Conditions (the effects may be shown analytically) - Surface crosswind component of 15 knots. Surface downward component of 10 knots. Wind shear of 4 knots per 100 feet altitude applied along the runway or across the runway individually, commencing at an altitude of 500 feet.
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AC 120-29 CHG 1 Appendix 1 15 Dec 71 Page 7
(3) Mode Selection and Indication -
(a) Manual selection should be positive, and the selection should be clearly identified.
(b) When the mode of operation is not shown by the manual mode selector and by the command display behavior, means should be employed to clearly annunciate the existing mode.
(4) Localizer Performance -
(a) The airplane should be stabilized on the localizer for the purpose of demonstration before the outer marker is intercepted on a normal inbound approach.
(b) From the outer marker to an altitude of 300 feet above runway elevation on the approach path, the flight director should cause the airplane to track within † 35 microamperes (95 percent probability) of the indicated localizer course.
The performance should be free of sustained oscillations.
(c) From an altitude 300 feet above runway elevation on the approach path to the decision altitude (100 feet), the [light director should cause the airplane to track to within † 25 microamperes (95 percent probability) of the indicated course. The performance should be free of sustained oscillations.
(5) Glide Slope Performance -
(a) For the purpose of the demonstration, the airplane should be stabilized on the glide slope before an altitude of 700 feet above the field level is reached.
* (b) From 700 feet altitude to the decision altitude (100 feet), the flight director should cause the airplane to track the center of the indicated glide slope to within † 35 microamperes or + 12 feet, whichever is the larger, without * sustained oscillations.
e. Automatic Throttle System.
(1) An automatic throttle system, if used, should provide safe operation under conditions which can reasonably be expected in normal service, including wind shear, gusts and sideslips.
The system should:
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Appendix 1 AC 120-29 CHG 1 Page 8 15 Dec 71
(a) Automatically adjust throttles to maintain airplane speed to within + 5 knots of stabilized programmed airspeed, but not less than computed threshold airspeed under all intended flight conditions. Proper operating points such as reference speed or angle-of-attack may be set manually or automatically.
(b) Provide throttle application at a rate consistent with the recommendations of the appropriate engine and airframe manufacturers.
(c) Maintain stable short period and phugoid airplane modes for all intended flight situations during manual and automatic flight control.
(2) Malfunction of any part of the system should not restrict either pilot from maintaining safe control of the airplane or engines.
(a) Disconnect switch(es) readily accessible to both pilot and copilot should be provided.
(b) The throttle drive mechanism should be designed to permit manual overriding without application of excessive throttle forces.
(c) The maximum servo velocity attainable should be positively limited by design to that required for adequate performance.
(d) Appropriate indication of system engagement and disengagement should be provided.
£. Radio Altimeter. The radio altimeter system should provide the following performance under the test conditions stated:
(1) Display to the flight crew clearly and positively the altitude information in flight which indicates the airplane main landing gear wheel height above terrain. With respect to the basic tee, the barometric altimeter may be positioned to the flight and adjacent to the radio altimeter.
(2) Under the measurement conditions described, the flight crew presentation should:
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AC 120-29 CHG 1 Appendix 1 15 Dec 71 Page 9
(a) Display altitude to an accuracy of ‡ 5 feet or ‡ 5 percent of altitude, whichever is greater, under the following conditions:
Pitch angle zero + 5° about the mean approach attitude.
2 Roll angle zero to + 20°.
З Forward velocity from minimum approach speed up to 200 knots.
4 At altitudes from 100 to 200 feet with sink rates of zero to 15 feet/second.
(b) Over level ground the altimeter should track the actual altitude of the airplane without significant lag or oscillation.
With the airplane at an altitude of 200 feet or less, any abrupt change in terrain representing no more than 10 percent of the airplane's altitude should not cause the altimeter to unlock, and indicator response to such changes should not exceed 0.1 seconds. If the system unlocks, it should reacquire the signal in less than one second.
(d) Systems which contain a push-to-test feature should test the entire system (with or without antenna) at a simulated altitude of less than 500 feet.
(e) Failure Warning - The system should provide to the flight crew a positive failure warning display any time there is a loss of power or absence of ground return signal within the specified range of operating altitudes.
g. Aircraft Configuration Change. The aircraft should be stabilized on the approach at glide slope intercept in the landing configuration with no late stage configuration changes permitted. If the applicant elects to use a flap setting lesser than landing flap, suitable landing performance information must be provided.
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(2) (1) described below: guidance to the ILS reference datum and consists of the elements Category II performance standards and provides continuous electronic Electronic Guidance System. An instrument landing system which meets SECTION I - CATEGORY II GROUND SYSTEM basis of a comparable level of safety. may be approved in accordance with the provisions of ICAO Annex 3 on a Foreign airports served by United States carriers or commercial operators Standards or other Service as appropriate. Category II minimums. Such an evaluation shall be conducted by Flight equivalent level of safety exists, may be authorized appropriate ILS Appendix, but where an operational or other evaluation identifies that an conditions. Airports which do not meet the criteria established in this touchdown, and along the runway for rollout, under the appropriate RVR cues to the pilot from the decision height down to and including the accuracy. The visual guidance system must provide the correct visual guiding an aircraft to the ILS reference datum with a high degree of and visual Circular. Office or by writing to the address on the title page of this Advisory equipment characteristics and are available at any Airport District Orders, Notices, and Advisory Circulars define system performance and ance criteria for Category II ILS operations. Other FAA Selection PURPOSE. This Appendix outlines ground system and obstruction clear- APPENDIX 2. 9/25/70 AC 120-29 method of identifying the decision height. Category II ILS installation as a system requirement and is one beacons, a 75 mc inner marker beacon is provided at each VHF Marker Beacons. In addition to the outer and middle marker ence datum as indicated in the U.S. Flight Inspection Manual. plane from the specified coverage limit down to the ILS refer- Glide Slope. The glide slope provides guidance in the vertical indicated in the U.S. Flight Inspection Manual. specified coverage limit down to the ILS reference datum as Localizer. The localizer provides azimuth guidance from the guidance systems. The electronic system must be capable of A Category II ILS approach system consists of both electronic CATEGORY II OPERATIONS GROUND SYSTEM AND OBSTRUCTION CLEARANCE CRITERIA FOR Page 1 Appendix 2
Appendix 2 AC 120-29 Page 2 9/25/70 Visual Guidance System. The Category II lighting system provides continuous visual guidance from the point where transition from Category II instrument flight to visual reference is initiated. The Approach Lighting System. Pending retrofit to Category II lighting standards outlined in Selection Order 1010.39, ILS.
Category II operations will be authorized on the present Category I, Configuration "A", 3000-foot approach lighting system (ALS). When retrofitted, these and all subsequent Category II ALS will conform to Selection Order 1010.39 except that no negative gradient will be permitted in the inner 1500 feet. Where required, and when fixtures are available, approved flush approach lighting system may be installed, i.e., displaced landing threshold.
Touchdown Zone Lighting System. A touchdown zone lighting system will be provided for each Category II ILS runway defining the runway touchdown zone and conforming to AC 150/5340-4B.
Centerline Lighting System. A centerline lighting system will be provided for each Category II ILS runway defining the runway centerline and conforming to AC 150/5340-4B. Existing L-842 300 candlepower centerline lights on 25-foot spacing may be approved for 1600 RVR day, and 1200 RVR night. 1200 RVR day and night may be approved for existing L-843 and I-850 runway centerline lighting systems.
High Intensity Runway Edge Lighting. A high intensity runway edge lighting system will be provided for each Category II ILS runway defining the lateral and longitudinal limits of the runway and conforming to AC 150/5340-13A. The operating limit of existing L-818, L-819, or L-820 runway edge light systems will be determined by the FAA on an individual basis.
(5) Taxiway Turnoff Lighting Systems. Taxiway turnoff lighting systems are not required for Category II operations. The FAA policy on these systems is contained in FAA Selection Order 1010.40.
All-Weather Runway Markings. Category Il runways will be marked with all-weather runway markings as specified in AC 150/5340-1C.
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AC 120-29 Appendix 2 9/25/70 C• Other Requirements. The following additional systems are required as part of the Category Il ILS system.
(1) Runway Visual Range (RVB).
(a) For operations below 1600 RVR, two transmissometers are required to provide visibility information at the approach and rollout ends of the Category II runway. Where an initial transmissometer installation is being made on a Category Il runway, both transmissometers will be installed on a 250-foot baseline. Where a Category I runway is updated to Category II status, the touchdown zone transmissometer may be on a 500 or 250-foot baseline: On the rollout end of the Category II runway, the transmissometer will be installed on a 250-foot baseline.
(b) Transmissometers serving other runways may be used to provide the RVR information in the rollout area of the Category II runway. Where transmissometers from other runways are used for this purpose, the transmissometer will be located within a radius of 2000 feet of the rollout threshold of the Category II runway and will provide a minimum of 2000 feet coverage of the Category II rollout area as measured from the rollout threshold of the Category II runway.
(c) FAA Standard 008 prescribes installation criteria for RVR equipment.
(2) Radar (Radio) Altimeter Setting Height. Radar (radio) altimeter setting heights will be provided on the FAA Form 8260-7, indicating the vertical distance at the 100/150-foot decision heights between the glide slope and the terrain beneath these points, on the runway centerline extended.
(3) Remote Monitoring. Remote monitoring shall be provided for the following elements of the Category II ILS system:
(a) Glide slope, localizer, and marker beacons.
(b) Approach lighting system.
(4) Manual Inspection. The following systems are not remotely monitored and will require frequent inspection by airport management or FAA personnel or frequent pilot reports to determine if they are operated and maintained in accordance with the criteria.
(a) Touchdown zone and centerline lights.
(b) Runway edge lights.
(c) Runway markings.
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Appendix 2 Page 4 AC 120-29 9/25/70
d. Critical Areas. Category II ILS glide slope, localizer, and operations. These areas are shown in Figure I and defined as * neo ares are stom a Figure one to ted a .
follows:
(1) Glide Path Critical Area. The glide path critical area is a rectangular area extending from the glide slope transmitting antenna to:
(a) 1000 feet in the direction of the approach end of the runway, or to the end of the runway, whichever is greater.
(b) "O" feet in the opposite direction.
(c) To the near edge of the runway which the ILS serves.
(d) 175 feet in the direction away from the runway.
Localizer Critical Area. The localizer critical area is a rectangular area extending from the localizer transmitting antenna 1000 feet in the direction of the approach end of the runway and 200 feet on either side of the runway centerline. An additional area is described as a circular area with a radius of 250 feet from the center of the localizer and connecting to the parallel lines on either side of the runway.
Obstacle Critical Area. The obstacle critical area is a rectangular area longitudinally centered on the runway centerline, extending from a point 200 feet outward from the Category II landing threshold (normal or displaced) and extending 3200 feet in the direction of landing and having a total width of 800 feet.
Aircraft on Ground. Procedures should be established to prevent taxiing aircraft awaiting departure from approaching closer than 400 feet to the runway centerline while a Category II ILS landing is being made. The distance shall be measured to the nearest point on the longitudinal axis of the aircraft with the aircraft positioned either parallel to or facing the runway.
4. OBSTACLE CLEARANCE CRITERIA. This section prescribes the obstacle clearance criteria for the final and missed approach areas for use in the formulation of ILS Category II procedures.
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ẠC 120- 29 Appendix 2 9/25/70 Page 5
• 008 , 00+ 1000' (SEE NOTE 2) SEE NOTE 1 15 ' MAX 200• NOTE 1. Location of hold lines when operations are permitted on a 400' parallel taxiway.
GLIDE SLOPE TRANSMITTER ANTENNA 32001 2. Or to the end of the runway, whichever is greater. CATEGORY IT CRITICAL AREAS
OPTIONAL TAXI SIGN LOCATION CENTER OF LOCALIZER ARRAY 1000' TAXI SIGN (TYP) PER TSO-N23 LOCALIZER CRITICAL AREA GLIDE PATH CRITICAL AREA OBSTACLE CRITICAL AREA SEE NOTE FIGURE 1.
Appendix 2 AC 120-29 Page 6 9/25/70 Final Approach. The final approach begins at the Final Approach Fix (FAF) and ends at the runway or missed approach point (DH).
The FAF in ILS procedures is the point where the glide slope is intercepted and descent to the authorized decision height has begun.
The FAF may be identified by an outer marker, compass locator, DME, radar, or other fix.
b. Final Approach Area. The final approach area has the following dimensions:
Length. The basic final approach area is 50,000 feet long, measured outward along the final approach course from a point 200 feet outward from the runway threshold. The final approach area used in a procedure shall be that portion of the basic area which is between the FAF and the 200-foot point outward from the runway threshold.
The final approach is centered on the extended runway centerline. It has a total width of 1,000 feet at the inner end and expands uniformly to a total width of 16,000 feet at the outer end which is 50,000 feet from the point of beginning.
Final Approach Surface. The final approach surface is an inclined plane which originates at the runway threshold elevation, 200 feet outward from the threshold, and which overlies the final approach area. The surface is divided into two sections; an inner 10,000- foot section and an outer 40,000-foot section. The slope of the surface changes at the 10,000-foot point. The exact gradient may differ according to the angle at which the glide slope is established. The 50:1 and 40:1 slopes which are applicable to the 2-1/2 degree glide slope shall be established unless other slopes must be used to assure required clearance over existing obstructions. The table below specifies slopes which provide minimum required obstruc- . tion clearance for several glide slope angles.
GS Angle Slope of Inner Section Slope of Outer Section 2 degrees 94:1 60:1 2-1/4 degrees 65:1 48:1 2-1/2 degrees 50:1 40:1 2-3/4 degrees 40:1 34:1 degrees 34:1 29.5:1 Final Approach Area Transitional Surfaces. Transitional surfaces are inclined planes with slopes of 7:1, which extend outward and upward from the edge of the final approach area, starting at the height of the approach surface and extending for a lateral distance of 5,000 feet at right angles to the runway centerline.
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