AC 120-29 Page 7 (and 8) 9/25/70
(b) When the pilot in command has demonstrated a raw data ILS approach, one system must be operative at the time air ore caste of flight release, if a combination of weather reports and forecasts indicates the weather at the destination airport will be below 3/4-mile visibility or RVR 4000 at the estimated time of arrival.
Category Il Operations. Both systems must be operative at the time of flight release if a combination of weather reports and forecasts indicates that Category Il weather conditions will exist at the destination airport at the estimated time of arrival.
b. Single Flight Director or Approach Coupler.
Category I Operations. The applicable system must be operative at the time of flight release if a combination of weather reports and forecasts indicates the weather at the destination airport will be below 3/4-mile visibility or RVR 4000 at the estimated time of arrival.
Category Il Operations - Two-Engine Propeller Aircraft ONLY.
The applicable system must be operative at the time of flight release if a combination of weather reports and forecasts indicates that Category II weather conditions will exist at the destination airport at the estimated time of arrival.
NOTE: Pilots MUST have demonstrated a raw data ILS approach.
FOREIGN AIR CARRIERS. The operations specifications of foreign flag air carriers may be amended to authorize the weather minima specified in Figure 1-1, provided such air carriers are authorized these minima Chap 1 Par 6
AC 120-29 CHG 2 Page 9 7/27/72 CHAPTER 2. ADDITIONAL CATEGORY I1 CRITERIA
8. GENERAL. The material contained in this chapter and Appendices 1, 2 and 3 is applicable to the approval of Category II weather minima.
9. OPERATIONAL PROCEDURES. Procedures and instructions to be used and adhered to by its flight crews are to be developed by each air carrier to include, as applicable, at least the following:
a. Approach monitoring. Crewmember duties during a Category Il approach are to be clearly delineated in the operations manual.
b. Testing of the radar (radio) altimeter by either a functional test or an acceptable operational procedure.
c. Use of RVR information.
d. Decision region. The region between the middle marker and the 100' point where the pilot must decide to either continue his approach or execute a go around. Instructions to pilots should include the maximum permissible excursions of the raw ILS deviation from which a landing can be made.
e. Missed approach procedure.
f. Use of airborne low approach equipment including cross-over system, if provided.
g. Instrument failure warning system.
10. AIRBORNE SYSTEM EVALUATION. Performance of the flight control guidance system may be demonstrated by showing compliance with either:
a. The criteria contained in Appendix 1, or
b. The provisions of paragraph 1l below.
* NOTE: Compliance with Appendix 1 or paragraph 11 constitutes equipment and installation approval only. The applicant must still comply with the maintenance program requirements of paragraph 13 before Category II operational approval can be obtained. *
11. OPERATIONAL DEMONSTRATION OF THE LOW APPROACH SYSTEM. The following provisions apply to an applicant selecting this method of demonstrating its airborne system:
a . Conduct at least 300 approaches to 100' in each aircraft type, except that if additional aircraft types are configured with the same basic low approach system, the additional approaches may be reduced by one-half. These approaches may be accomplished in line operations or during training and demonstration flights or any Chap 2 Par 8
Page 10 AC 120-29 9/25/70 combination thereof. Eighty-five (85%) percent of the total demonstrations conducted during line operations must be successful and 90 percent conducted during training or demonstration flights must be successful. (See paragraph 11.c. for a definition of a successful approach.) Approaches are to be accomplished in accordance with the following:
A minimum of three ILS facilities are to be used during the demonstrations and at least 10 percent of the total approaches are to be conducted on each of at least three of the facilities selected. The number of approaches conducted on additional facilities can be at the applicant's discretion.
(2) The low approaches should be accomplished on Category II ILS facilities. However, at the applicant's option, demonstration may be made on Category I ILS facilities.
(3) No more than 15 approaches per day are to be conducted on a single facility.
(4) No more than 60 percent of the approaches are to be conducted in any single aircraft.
(5) Where an applicant has different models of aircraft within a given type which utilize the same basic flight-control guidance system, the applicant is to assure that the various models comply with the basic system performance criteria.
(6) A representative number of pilots assigned to an aircraft type are to be used in the conduct of these approaches. No single pilot in command shall perform more than 15 percent of these approaches except when the total number of crews located at a small domicile requires a greater percentage.
(7) At least 30 percent of the approaches will be observed by FAA Air Carrier Operations Inspectors.
b. Data Collection During Airborne System Evaluation. Each applicant is to develop a form to be used by the flight crews to record data listed below. This form will be completed whenever an approach is attempted utilizing the airborne low approach system regardless of whether it is initiated, abandoned or concluded successfully.
The completed forms will be made available to the assigned FAA Principal Operations Inspector for his evaluation.
(1) If unable to initiate approach due to a deficiency in the airborne equipment, state deficiency.
(2) If approach is abandoned, give reasons and altitude above runway at which approach was discontinued.
Par 11 Chap 2
AC 120-29 Page 11 9/25/70
(3) Adequacy of speed control at the 100' point (if auto throttle used) .
(4) Was airplane in trim at the 100' point for continuation to flare and landing?
(5) Compatibility of flight director with auto coupler.
Diagram of cockpit raw ILS display and diagram of runway extended to middle marker. Flight crew to indicate position of airplane at middle marker, 100' point and estimated touchdown point.
(7) Quality of overall system performance.
NOTE: Unsuccessful approaches attributed to ATC instructions may be excluded from the statistical data; for example, flights vectored too close in for adequate localizer and glide slope capture and ATC requests to abandon approach. Also, unsuccessful approaches may be excluded from consideration when they are due to faulty ground station signals and where a pattern of such faulty performance can be established.
c. Definition of a Successful Approach. For the purpose of the airborne system evaluation, a successful approach is one in which, at the 100' point:
(1) The airplane is in trim so as to allow for continuation of normal approach and landing.
(2) The indicated airspeed and heading are satisfactory for a normal flare and landing. If an auto throttle control system is used, speed must be † 5 knots of programmed airspeed but may not be less than computed threshold speed.
(3) The airplane is positioned so that the cockpit is within, and tracking so as to remain within, the lateral confines of the runway extended.
(4) Deviation from glide slope does not exceed ‡ 75 microamps as displayed on the ILS indicator.
(5) No unusual roughness or excessive attitude changes occur after leaving middle marker.
Chap 2 Par 11
Page 12 AC 120-29 CHG 2 7/26/72
12. SYSTEM FAULT DETECTION. The applicant is to submit a description of the proposed Category II system which outlines the methods of detecting and protecting against the consequences of single failures. Warning flags that are used must be easily discernible under all lighting conditions. The following, as appropriate, will be treated in the des~ cription:
a. Attitude (vertical gyro).
b. Heading.
c. Auto throttle system.
d. Altitude.
e. ILS instrument.
f. Flight director system.
g. Any other equipment essential to the system.
13. MAINTENANCE PROGRAM. Each applicant is to establish a maintenance program, acceptable to the FAA, to assure that the airborne electronic equipment will continue at the level of performance and reliability demonstrated during the evaluation program. The following are the minimum requirements:
Reliability Reporting. For a period of one year after an applicant requirements, and reduced minima are authorized, the operator is to provide a monthly summary to the FAA of the following information:
(1) The total number of approaches where the equipment constituting the airborne portion of the Category II system was utilized to make satisfactory actual or simulated approaches to Category Il minima (by aircraft type).
The total number of unsatisfactory approaches and the reasons therefore (broken down into appropriate categories - airborne equipment faults, ground facility difficulties, aborts of approaches because of ATC instructions) by airport and aircraft registration number.
* (3) The total number of removals of avionic components within the systems upon which the applicants Category II approval was based.
b. Each applicant is to establish an initial and recurrent training program, acceptable to the FAA, for personnel performing maintenance work on Category II airborne systems and equipment. Training records for such personnel are to be kept current and made available to the FAA for inspection. * Par 12 Chap 2
AC 120-29 CHG 2 Page 13 7/26/72 Test Equipment and Standards. The operator's program for maintenance of line (ramp) test equipment, shop (bench) test equipment, and a listing of all primary and secondary standards utilized during maintenance of test equipment which relate to Category II operations are to be submitted to the FAA for determination of adequacy. Emphasis will be placed on standards associated with ILS receivers, flight directors, autopilot/couplers and altimeter systems.
d. patien or fatations d. Maintenance Procedures. Any changes to maintenance procedures, practices or limitations which were established in qualification for Category II operations are to be submitted to the FAA for acceptance before any such changes are adopted.
Engineering Modifications. Titles and numbers of all modifications, additions and changes which were made to qualify aircraft systems for Category II performance are to be provided to FAA.
14. APPROVAL OF CATEGORY II WEATHER MINIMA.
U.S. Operators. When an applicant has complied with the appropriate provisions of these criteria, operations specifications authorizing 1600 RVR with a 150-foot decision height will be issued. During the six-month period following the issuance of these specifications, the air carrier, when practicable, should use the Category II airborne system regardless of weather minimums, to ensure continued performance and reliability of the system. If there is a significant deterioration in the performance and reliability of the airborne equipment, approval of 1200 RVR will be withheld and authorization for 1600 RVR may be suspended unless positive corrective action is taken. When the operator excercises its airborne systems at airports where the IlS is not of Category II quality, or when other conditions not normal for Category II approaches are encountered, the performance standards specified for normal Category II conditions need not be met. When the first six months of operations have been analyzed and found acceptable, the operator will be authorized to operate at 1200 RVR with a decision height of 100 feet.
b. Foreign Air Carriers. Foreign flag air carrier operations specifications may be amended to authorize Category II landing minimums in accordance with paragraph (a) above, provided the air carrier:
(1) Is authorized for these minima by the State of Registry, and
(2) Certifies that its Category II program is equivalent to that required for U.S. air carriers by this advisory circular.
Chap 2 Par 13
Par 1 ground navigation facilities and the Air Traffic Control System, and installation practices, freedom from interferences, compatibility with and in flight. It should include determination of satisfactory conformity inspections and tests to be conducted, both on the ground document should be issued. This document will specify the necessary prescribed criteria, a Type Inspection Authorization, or similar Category II installation indicating that the system will meet the evaluations on the combination of systems proposed as a basis for a Aviation Administration engineering design and ground testing program of the pertinent systems installed. Upon completion of Federal ducted to determine compliance with the requirements of this document applicant on his proposed flight test program, which should be con- INSPECTION AND TEST PROGRAM. Agreement should be reached with the of the appropriate Federal Aviation Regulations. validation which has been found to be compatible with the intent Administrator; e.g., military standards or a foreign government's c. Found to comply with other pertinent specifications adopted by the supplemental type certificate, or approved as part of an airplane under a type certificate or b. Found to comply with applicable Federal Aviation Regulations and standard order or type certificate, or a. Found to comply with the requirements of an applicable technical part of an installed system when it is: flight control equipment may be eligible for installation approval as EQUIPMENT APPROVAL CRITERIA. Airborne navigation instrument and/or found to be equivalent and approved by the FAA. cation based on other criteria may also be considered acceptable when airworthiness for use in Category II IFR operations. Type certifi- sidered acceptable methods of determining transport category airplane facilities. The guidelines and procedures contained herein are con- should be based on demonstrated compatibility with Category II ground accuracy, reliability and failsafe features. In addition, approval of factors such as the intended function of the installed system, its system installations and test methods should be based on a consideration GENERAL CRITERIA. The type certification approval for the equipment, Category II performance. statement in approved flight manuals that his equipment meets equipment and their installations when the applicant desires to have a This appendix contains criteria for the approval of airborne CATEGORY AIRCRAFT. NAVIGATION, INSTRUMENT, AND FLIGHT CONTROL SYSTEMS IN TRANSPORT APPENDIX 1. AIRWORTHINESS APPROVAL FOR CATEGORY II INSTALLATION OF AIRBORNE 9/25/70 Page 1 Appendix 1 AC 120-29
Appendix 1 AC 120-29 Page 2 9/25/70 performance of intended functions. Performance testing in flight should cover representative and critical phases of operation including equipment malfunction simulation.
RESERVED.
6. APPROVED AIRPLANE FLIGHT MANUAL OR MARKINGS OR PLACARDS. Upon satisfactory completion of an engineering inspection and test program, the FAA airplane flight manual or supplement thereto, or markings or placards should reflect the following:
a. The limitations, if any.
b. Revision to the performance section, if appropriate.
c. A statement of CAT II approval to the effect that, "The airborne instruments and equipment meet the performance standards of Appendix 1 of this advisory circular.
NOTE: Compliance with the performance standards referenced above, does not constitute approval to conduct Category II operations.
SYSTEMS PERFORMANCE REQUIREMENTS. For the combination of systems to provide the level of accuracy, reliability, and compatibility needed to assure an approach capability which is considered acceptable to the Administrator, each individual system should be found to perform its intended function in accordance with the following:
Control Functions. All systems which furnish signals directly to the airplane flight control system or the propulsion thrust control system should be so designed that if malfunction occurs, such malfunction does not result in an unsafe configuration. Means for quick disengaging or overriding of each automatic control function should be immediately available to the flight crew without requiring the application of excessive forces and the assuming of any unusual position.
b. Malfunction of Monitoring Functions. A reasonable probable malfunction in any monitoring subsystem should be incapable of causing a malfunction of any ESSENTIAL system unless such essential system malfunction is indicated to the flight crew.
COMBINED SYSTEMS CRITERIA.
a. Eligibility for Category II operations includes compliance with applicable sections of Federal Aviation Regulations, Part 25.
b. A combination of airborne navigation, instrument, and flight control systems, having individual system installation approvals, may be eligible for Category II installations approval when:
Par 4
AC 120-29 Appendix 1 9/25/70 Page 3
(1) Found to provide information to the flight crew with sufficient accuracy and reliability to permit the manual control of the airplane along the flight path within prescribed limits.
(2) Or found to provide signals to the airplane flight control systems with sufficient accuracy, and reliability to maintain the aircraft along the approach flight path within prescribed
(3) Or found to provide a combination of automatic flight, propulsion control, and other information to the flight crew to permit manual control of the aircraft, supplemented by automatic control, along the approach flight path within prescribed limits.
9. INDIVIDUAL SYSTEM CRITERIA. Individual Category II airborne systems should comply with the pertinent sections of this appendix and the following performance criteria:
Localizer. The localizer system installation should comply with the following:
The localizer equipment should meet or exceed the minimum performance standards set forth in Federal Aviation Administration dated 15 December 1965, "Minimum Performance Standards - ILS Technical Standard Orders C36, C36a, C36b, or RICA Paper DO-131 Localizer Receiving Equipment.
The localizer system installation should meet or exceed the minimum performance standards set forth in RTCA Paper 69-60/ DO-102, dated 12 April 1960, "Minimum In-Flight Performance Standards - ILS Localizer Receiving Equipment."
(3) Display to the pilot positive visual indication to show degradation of localizer system performance under the following conditions:
(a) The absence of either or both modulation signals.
(b) The reduction of both modulation signals to one-half the normal 20 percent.
(c) When a difference of depth of modulation equal to 0.093+
0.002 produces an output of less than one-half normal response to this standard localizer deviation signal.
(4) The localizer receiving centering error should be within 5 ua on a 95 percent probability basis under the following conditions, using a standard test signal:
Par 8
Par 9 Page 4 Appendix 1 installation approval. lined in RICA Paper 222-58/D0-89 are applicable for Category II Centering Error: - The glide slope centering requirements out- response to this standard glide slope deviation signal. .002 produces an output of less than one-half normal When a difference of depth of modulation equal to 0.091+ their normal 40 percent. (b) The reduction of both modulation signals to one-half of (a) The absence of either or both modulation signals. conditions: dation of glide slope system performance under the following (3) Display to the pilot positive visual indication to show degra- Standards - ILS Glide Slope Receiving Equipment." DO-101, dated 9 December 1959, Minimum In-Flight Performance minimum performance standards set forth in RTCA Paper 233-59/ (2) The glide slope system installation should meet or exceed the Standards - ILS Glide Slope Receiving Equipment." RICA Paper DO-132 dated 15 March 1966, Minimum Performance Administration Technical Standard Orders C34, C34a, C34b, or performance standards set forth in Federal Aviation The glide slope equipment should meet or exceed the minimum the following: Glide Slope. The glide slope system installation should comply with Slope Receivers." Standard Adjustment Criteria for Airborne Localizer and Glide ance with RICA Paper 23-63/D0-117, dated 14 March 1963, The localizer receiving equipment should be adjusted in accord- plane will require special coordination. over a different temperature range in a particular air- temperature range is defined as +10°C. to +40°C. Operation expected during a normal ILS approach. The nominal ambient (c) Variation of ambient temperature over the limited range AC power over the range of 105 to 120 volts. (b) Variation of DC power over the range of 24 to 28 volts or expected during the final phase of an ILS approach. NOTE: This represents the variation of R.F. signal level Variation of R.F. signal level from 50 to 1,000 uv. 9/25/70 AC 120-29