AC 120-79A

Change 1

Advisory circular · Developing and Implementing an Air Carrier Continuing Analysis and Surveillance System

Approved
May 17, 2013
Last reviewed
August 20, 2024
This change
CHG 1 to AC 120-79A.
Cancels
AC120-79A
Family
AC 120-79 · 3 versions
Revision
A, change 1
14 CFR parts
121, 135, 119, 1, 129, 125, 133, 137, 43

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 21, 2025.

Show pages 41–52

Par 11-1 Page 55 (and 56) CHAPTER 11. ADMINISTRATIVE INFORMATION

11-1. HOW TO OBTAIN THIS AND OTHER FAA PUBLICATIONS.

a. AC 00.2 and AC 00-44. The current edition of AC 00.2, Advisory Circular Checklist and Status of Other FAA Publications, contains a listing of all ACs. The current edition of AC 00-44, Status of Federal Aviation Regulations, contains a listing of the Code of Federal Regulations (CFR) and current prices.

b. ACs Online. You can get copies of this and other ACs online at http://www.faa.gov/regulations_policies/advisory_circulars.

c. Regulations Online. You can also obtain a copy of current regulations online at http://www.gpoaccess.gov/ecfr.

d. CFR and ACs by Mail. You can obtain the CFR and ACs for a fee from the following address:

Superintendent of Documents P.O. Box 371954 Pittsburgh, PA 15250-7954

e. Mailing List. For placement on our mailing list of free ACs, contact:

U.S. Department of Transportation Subsequent Distribution Office SVC-121.23 Ardmore East Business Center 3341Q 75th Avenue Landover, MD 20785

f. FAA Web Site. Our Web site is located at http://www.faa.gov. The FSIMS Web site is located at http://fsims.faa.gov.

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Appendix 1 APPENDIX 1. SAMPLE CASS FOR A LARGE CERTIFICATE HOLDER Type of Certificate Holder Fleet composition 250 turbojet airplanes; B-737, B-757, A-320.

Number of maintenance base and line stations Base station and 25 line stations.

Proportion of maintenance contracted to third parties All letter checks, overhauls, and major maintenance performed in-house. Some line maintenance, parts work, and off-wing engine work is contracted.

Scheduled or on-demand Scheduled (Title 14 of the Code of Federal Regulations (14 CFR) part 121).

Size and structure of the maintenance organization Engineering and maintenance organizations include extensive engineering capability, quality assurance (QA) department, full range of shops for support, components, electronics, engines, etc.

a. Continuing Analysis and Surveillance System (CASS) Management and Planning.

b. General Priority. This certificate holder prioritizes in the following general manner:

(1) Safe operations (air and ground).

(2) Detect and prevent noncompliance.

(3) Improve operating efficiency.

c. CASS Written Procedures (A System Safety Attribute: Procedures). A separate CASS manual contains the CASS written procedures. The CASS appendix is detailed, including specific procedures for root cause and systems analysis and discussion of how to address human factors.

d. CASS in the Certificate Holder Organization. The senior vice president of engineering and maintenance (14 CFR part 119, § 119.65 Director of Maintenance (DOM)) has overall authority and responsibility for this air carrier’s maintenance program, including the CASS. The CASS specifically appears on the functional organizational flowchart.

e. Authority for CASS (A System Safety Attribute: Authority). The director of QA holds the direct authority for the CASS.

f. Responsibility for CASS (A System Safety Attribute: Responsibility). The CASS board has direct responsibility for the CASS. The manager of the CASS chairs the board and reports to the director of QA.

Appendix 1

g. Policy for CASS Auditor/Analyst Independence from Production (A System Safety Attribute: Controls). CASS auditors/analysts are in a separate department under QA.

Operational data collection and analysis are assigned to the reliability group (within the certificate holder’s Federal Aviation Administration (FAA)-approved reliability program) in the engineering department. The reliability group reports CASS information directly to the CASS board.

h. Policy Regarding Personnel Actions Resulting from CASS Findings/Results. The certificate holder’s policy is consistent with its participation in Aviation Safety Action Programs (ASAP) and the Voluntary Disclosure Reporting Program (VDRP). Inadvertent errors do not lead to disciplinary action or FAA enforcement action. Full reporting and disclosure are encouraged to facilitate system corrections.

i. Surveillance and Analysis of Performance of Maintenance Program.

Audits Responsibility Manager of CASS.

Prioritization CASS board develops a surveillance plan based on risk assessment.

Cycles The CASS board assigned each area an onsite audit accomplished semiannually to every 5 years, depending on the risk assessment. Also depending on the risk assessment, some areas never receive an onsite audit assignment. The CASS board updates the annual audit plan quarterly.

Scope CASS covers all internal and third-party areas of maintenance.

Coordinating Agencies for Supplier’s Evaluation (C.A.S.E.) audits may indicate the need for followup audits or may be integrated into the CASS.

Process Full-time CASS auditors use checklists and conduct annual interviews of personnel at all levels of maintenance to uncover concerns or latent problems. The CASS department receives reports of all maintenance-related events, such as rejected takeoffs, for analysis and use in risk assessment for audits. Schedule special audits as needed.

The CASS also reviews self-audits from all departments. Some vendors conduct their audits by document reviews, written questionnaires, telephone followup, or combinations of these. Followup is required if preliminary results raise concerns.

Flow Report the initial results to the manager of CASS. The CASS board reviews summaries of all findings/initial analyses and details of issues as deemed necessary by the manager of CASS.

Appendix 1 Analysis Responsibility Auditors conduct preliminary analysis based on specific experience and training and internally developed guidelines that channel analysis to system root causes.

Perform preliminary root cause analysis Auditor/analyst.

Classify hazards/ perform risk assessment CASS board and analysts.

Flow The CASS board transmits results to the affected department, which assigns personnel to participate on the corrective action team under direction of the CASS board.

j. Surveillance and Analysis of Effectiveness of Maintenance Program.

Operational Data Collection Responsibility Manager of CASS.

Prioritization The reliability group determines priority based on risk assessment.

Scope Extensive. Ranges from pilot reports, Engine Condition Monitoring (ECM), mechanical delays, and teardown reports to data from special authorizations such as category II/III, extended range operation with two-engine airplanes, and operations in Reduced Vertical Separation Minimum (RVSM) airspace and minimum navigation performance specifications (MNPS) airspace.

Process In accordance with the certificate holder’s FAA-approved reliability program. Data collection is oriented toward detecting trends, positive or negative, before the occurrence of events. However, data collection (and analysis) may vary based on maintenance-related events. The CASS board formally reviews the list of operational data sets collected by the CASS board every 2 years to determine if it needs to be adjusted. The initial list is based on the current edition of Advisory Circular (AC) 120-17, Maintenance Control by Reliability Methods, and CASS board determinations.

Flow The reliability group, although located within the engineering department, has a direct reporting relationship to the manager of CASS.

Analysis of Operational Data Responsibility Reliability group.

Prioritization Reliability board.

Process Technical experts within the reliability group perform the analysis and make preliminary determination of possible root causes.

Flow Results are reported to the manager of CASS and the CASS board.

Appendix 1

k. Corrective Action.

Final Root Cause Analysis (RCA) Responsibility Manager(s) of technical area(s) affected.

Procedures The director of CASS transmits preliminary analysis results to the manager of the affected department, who designates technical personnel to coordinate final RCA with the auditor/analyst. The CASS auditor/analyst oversees the process and ensures that the formal RCA process, including human factors and systems analysis, is followed.

Use of specific analytical systems Internally developed analytical process and industry tools.

Flow The auditor/analyst and technical department develop a joint final report and submit it to their respective managers.

Determination of Corrective Action Options Responsibility The CASS board appoints a corrective action team to include the CASS auditor/analyst, reliability group, technical area(s) affected, and related areas potentially affected (for example, flight operations).

Procedures The team leader is from the technical area affected. Perform risk assessment of the problem and develop corrective action options. The CASS auditor/analyst or reliability group representative does not propose corrective actions but reviews options for systems considerations and relevance to RCA.

Flow The manager(s) of the affected area(s), working with the team, transmits options to the CASS board.

Selection of Corrective Action and Corrective Action Plan Responsibility CASS board.

Procedures Decision based on a priority for safety and regulatory compliance. Risk assessment is the basic tool to support the decision. CASS personnel do not participate in the development of the corrective action but review for systems considerations and relevance to RCA.

Flow Depends on the level of the problem and the corrective action. Routine issues may be resolved at the team level with direct implementation by the affected area manager; the CASS board is then advised of this action. More significant program changes may require prior review and concurrence from the CASS board. The CASS board may raise highest level decisions to the director of QA or senior vice president of engineering and maintenance.

Appendix 1 Followup Responsibility Manager of CASS.

Procedures CASS auditor/analyst or reliability group, as applicable, assigned to develop a followup plan based on the seriousness of the problem.

Followup may include communications from technical area verifying effectiveness, followup audits or data collection, and/or a followup evaluation.

Flow The technical area reports implementation status to the manager of the CASS, who informs the CASS board. The CASS board may inform the director of QA if the problem is sufficiently serious or the implementation plan is not followed.

NOTE: The above tables provide many examples of the system safety attributes: controls and procedures.

l. Communications Between CASS and Other Personnel (A System Safety Attribute:

Interfaces).

Communication of Specific CASS Results and Actions Responsibility CASS board.

Procedures Audits based on updated checklists. The CASS collects and stores operational data in computer systems, and some analysis and alerting features are automated. Audit and analysis results communicated through company electronic mail system, with acknowledgements.

Corrective action tracking through computerized database system.

Flow Electronic mail and standard electronic reports of information flow among CASS board, corrective action teams, technical areas, and director of QA, when applicable.

Communications with Maintenance Personnel Responsibility CASS board.

Procedures The CASS initial and recurrent training included for all personnel, including lectures from CASS personnel. Monthly newsletter summary to production areas regarding CASS activities.

Flow The CASS department works with the training and company communications department, and receives feedback from managers and supervisors, particularly in the maintenance areas.

Appendix 1 Interfaces (A System Safety Attribute: Interfaces) Responsibility CASS board.

Procedures Reliability group provides regular reports on analysis results, trends, and concerns.

Auditors/analysts provide regular reports on findings, analyses, trends, and concerns.

VDRP manager provides summaries of disclosures and proposed comprehensive fixes for CASS review and input.

Copies of C.A.S.E. audit results.

To CASS Board CASS auditors review reports from company ASAPs and at least annually review maintenance-related Aviation Safety Reporting Program reports for consideration in setting audit and operational data collection priorities.

Feedback to technical areas regarding findings, trends, concerns, and followup results.

Feedback to VDRP manager regarding proposed comprehensive fixes;

coordination with manager of CASS.

Monthly reliability analysis summaries and other CASS summaries for distribution to the vice president of engineering and maintenance, director of QA and other senior management, department managers in maintenance, flight and ground operations, Internal Evaluation Program (IEP), safety office, and FAA principal inspector (PI).

CASS reports reflect VDRP comprehensive fixes without detailing the initiating circumstances.

Semiannual summary report to chief executive officer (CEO).

Copies of reliability reports and CASS summaries to the FAA PI. The FAA PI has online access to CASS reports and documents such as summaries, analysis, trends, and corrective action tracking.

From CASS Board CASS board meeting minutes.

Flow Communications channeled through manager of CASS.

m. Personnel Who Perform CASS Functions.

(1) Full-time auditors and analysts; in some cases, an auditor may also be an analyst.

(2) All members of the CASS board who have not participated in specific CASS training receive a total of 16 hours initial training covering CASS, root cause and systems analysis, and human factors.

(3) Company has hired a human factors specialist to address issues across all departments and to participate on the CASS board.

Appendix 1 How the Certificate Holder Evaluates Its CASS (A System Safety Attribute: Process Measurement) Responsibility Senior vice president of engineering and maintenance.

Procedures IEP evaluates CASS annually.

Flow The CASS transmits IEP reports directly to the CEO and to the senior vice president of engineering and maintenance.

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Appendix 2 APPENDIX 2. SAMPLE CASS FOR A MEDIUM CERTIFICATE HOLDER Type of Certificate Holder Fleet composition 75 turboprop and turbojet airplanes; ATR–42, Canadair Regional Jets.

Number of maintenance base and line stations Base station and five line stations.

Proportion of maintenance contracted to third parties A, B, and C checks and most major maintenance in-house. Off-wing engine maintenance, avionics, and instrument overhauls contracted.

Scheduled or on-demand Scheduled (Title 14 of the Code of Federal Regulations (14 CFR) part 121).

Size and structure of the maintenance organization Engineering and maintenance organizations, including small engineering capability, shops for support, components, electronics, engines, etc.; and quality assurance (QA) department.

a. Continuing Analysis and Surveillance System (CASS) Management and Planning.

b. General Priority. This certificate holder prioritizes in the following general manner:

(1) Safe operations (air and ground).

(2) Detect and prevent noncompliance.

(3) Improve operating efficiency.

c. CASS Written Procedures (A System Safety Attribute: Procedures). An appendix to the general maintenance manual describes CASS. The detailed CASS appendix includes specific procedures for root cause and systems analysis, and discussion of awareness of human factors.

d. CASS in the Certificate Holder Organization. The chief executive officer (CEO) supports the CASS. CASS specifically appears on the functional organizational flowchart.

e. Authority for CASS (A System Safety Attribute: Authority). The senior vice president of engineering and maintenance (14 CFR part 119, § 119.65 Director of Maintenance (DOM)) has overall authority and responsibility for this air carrier’s maintenance program, including the CASS. In this case, the senior vice president of engineering and maintenance also has the direct authority for this air carrier’s CASS.

f. Responsibility for CASS (A System Safety Attribute: Responsibility). The director of QA heads the CASS board, which includes key department heads in engineering and maintenance, training, and flight operations.

g. Policy for CASS Auditor/Analyst Independence from Production (A System Safety Attribute: Controls). CASS auditor/analysts are in a separate department under QA.

Operational data collection and analysis assigned to a “CASS reliability group” that is contained

Appendix 2 within the engineering department. The CASS documentation is explicit that this certificate holder’s reliability program is not Federal Aviation Administration (FAA)-approved. The reliability group reports CASS information directly to the director of QA.

h. Policy Regarding Personnel Actions Resulting from CASS Findings/Results.

Inadvertent errors will not lead to disciplinary action. Encourage full reporting and disclosure to facilitate system corrections. Certificate holder participates in the FAA Voluntary Disclosure Reporting Program (VDRP).

i. Surveillance and Analysis of Performance of Maintenance Program.

Audits Responsibility Director of QA.

Prioritization CASS board develops audit plan based on risk assessment.

Cycles The CASS board reviews its established audit plan annually. The CASS board completes onsite audits on a semiannual or biannual basis, depending on the risk assessment. Also depending on the risk assessment, some areas never receive an onsite audit assignment.

Scope All internal and third-party areas of maintenance.

Process CASS board developed audit checklists for use by auditors. Auditors conduct their audits in accordance with the annual plan. The CASS department receives reports of all maintenance-related events such as rejected takeoffs for analysis and use in risk assessment for audits. The CASS may schedule special audits as needed. Some vendors conduct their audits by document reviews, written questionnaires, and telephone followup, or combinations of these. If preliminary results raise concerns, you must followup.

Flow Initial reports and summaries to director of QA.

Analysis Responsibility Director of QA.

Perform preliminary root cause analysis Auditor/analyst.

Classify hazards/ perform risk assessment CASS board and analysts classify hazards and perform risk assessment.

Flow Director of QA reports summaries of all findings/initial analysis and details of issues to the CASS board for review and concurrence. CASS board transmits results to affected department, which forms corrective action team.

j. Surveillance and Analysis of Effectiveness of Maintenance Program.

Appendix 2 Operational Data Collection Responsibility Director of QA.

Prioritization Reliability group.

Scope Includes pilot reports, Engine Condition Monitoring (ECM), mechanical delays, teardown reports, and other data.

Process Modeled after FAA-approved reliability programs. Data collection oriented toward detecting trends, positive or negative, before occurrence of events. However, data collection (and analysis) may vary based on maintenance-related events. The CASS board formally reviews collected operational data sets every 2 years; initial list based on Advisory Circular (AC) 120–17, Maintenance Control by Reliability Methods; and CASS board determinations.

Flow Reliability group, although located within the engineering department, has a direct reporting relationship to the director of QA.

Analysis of Operational Data Responsibility Director of QA.

Prioritization Reliability group.

Process Analysis performed by technical experts within the reliability group;

includes preliminary determination of possible root causes or possible procedural changes.

Flow Results are reported to CASS board.

k. Corrective Action.

Final Root Cause Analysis Responsibility Director of QA.

Procedures CASS board transmits preliminary analysis results to the manager(s) of the affected department(s), who designates technical personnel to conduct final RCA with CASS auditor/analyst. CASS analyst oversees the process and ensures the RCA process, including human factors and systems analysis, is followed.

Use of specific analytical systems Internally developed formal analysis process or common industry tools.

Flow Technical department develops final report and submits it to the director of QA.

Appendix 2 Determination of Corrective Action Options Responsibility Director of QA designates corrective action team, led by primary affected technical department(s), whose manager(s) designates a team leader.

Procedures Risk assessment of the problem and the options. The CASS auditor/analyst or reliability group representative does not propose corrective actions but reviews possibilities for systems considerations and relevance to RCA.

Flow Team presents recommendation to CASS board.

Selection of Corrective Action and Corrective Action Plan Responsibility Director of QA.

Procedures Decision based on a priority for safety and regulatory compliance. Risk assessment is the basic tool to support the decision. CASS board verifies systems considerations and relevance to RCA.

Flow Depends on the level of the problem and the corrective action. Routine issues may be resolved at the team level with direct implementation by the affected area manager; advise the CASS board of this action. More significant program changes may require prior review and concurrence from CASS board or elevation to vice president of engineering and maintenance.

Followup Responsibility CASS board.

Procedures CASS auditor/analyst or reliability group, as applicable, assigned to develop a followup plan based on the seriousness of the problem.

Followup may include communications from a technical area verifying implementation, followup audits or data collection, and/or followup evaluation.

Flow Technical area manager reports to director of QA, who reports to CASS board.

NOTE: The above tables provide many examples of the system safety attributes: controls and procedures.

l. Communications Between CASS and Other Personnel (A System Safety Attribute:

Interfaces).