Certification Authorities Software Team

Certification Authorities Software Team
Abbreviation	CAST
Formation	1990
Products	CAST Position Papers
Fields	Certification of airborne software and hardware
	No meetings since 2016.

Last updated April 09, 2024

The Certification Authorities Software Team (CAST) is an international group of aviation certification and regulatory authority representatives. The organization of has been a means of coordination among representatives from certification authorities in North and South America, Europe, and Asia, in particular, the FAA and EASA. The focus of the organization has been harmonization^[1]^[2] of Certification Authorities activities in part though clarification and improvement of the guidance provided by DO-178() and DO-254().

Activities

Since 1982, RTCA publication DO-178 has provided guidance on certification aspects of safety-critical software use in civil aircraft. In 1985, the first revision DO-178A was issued. The CAST organization first met November 1990 to develop consistent international certification authority input to the drafting of the next revision, DO-178B, which was released in 1992. In 2003, the organization expanded its scope to address the published certification guidance for airborne electronic hardware provided in the RTCA publication DO-254 released in 2000.^[1]

With application of DO-178B, it was discovered that many projects were not complying with DO-178B, but there was also wide variations in how various certification authorities conducted project assessments. In response, the CAST developed a standard software compliance assessment approach. In a manner similar to standard staged engineering design review practices (e.g., 10%-50%-90%-100% Complete), this introduced four standard milestones in a software development project where an FAA authority or representative would assess the applicant's progress towards compliance. A goal was to detect issues in time to for the applicant to make adjustments to maximize successful accomplishment of all certification objectives. The FAA further developed this approach in the "Mega" FAA Order 8110.49 Chapter 2, defining the four Stages of Involvement (SOI) Audits as Planning, Development, Verification (Test), and Final.^[3]

From 1998 on, the CAST provided informational recommendations in the form of a series of position papers that were neither policy nor guidance documents.^[4] These position papers were among the inputs to the joint RTCA/EUROCAE committee that developed DO-178C, DO-278A, DO-248C, and DO-330, and the technology supplements to these publications (DO-331, DO-332, and DO-333).^[1]

The model for international certification authority harmonization has changed since CAST's inception.^[5] Certification Management Team Collaboration Strategy now emphasizes direct collaboration with industry on technical topics.^[6] CAST has not met since October 2016 and the FAA has removed links to past CAST position papers from its website; Position Papers 1-26 were archived in 2015 and this archive was removed in 2017. All but one remaining position papers were later removed from the website and the link to the remaining CAST-32A will be removed after publication of AC 20-193.^[5]

Even though these legacy items have been removed, not all information they contain has been included in replacement publications, so, they remain a source of insight into present guidance.

Position Papers

Series	Subject	Year
CAST-1	Guidance for Assessing the Software Aspects of Product Service History of Airborne Systems and Equipment	1998
CAST-2	Guidelines for Assessing Software Partitioning/Protection Schemes	2001
CAST-3	Guidelines for Assuring the Software Aspects of Certification When Replacing Obsolete Electronic Parts Used in Airborne Systems and Equipment	1999
CAST-4	Object-Oriented Technology (OOT) in Civil Aviation Projects: Certification Concerns Status: Cancelled	2000
CAST-5	Guidelines for Proposing Alternate Means of Compliance to DO-178B	2000
CAST-6	Rationale for Accepting Masking MC/DC in Certification Projects	2001
CAST-7	Open Problem Report (OPR) Management for Certification	2001
CAST-8	Use of the C++ Programming Language	2002
CAST-9	Considerations for Evaluating Safety Engineering Approaches to Software Assurance	2002
CAST-10	What is a "Decision" in Application of Modified Condition/Decision Coverage (MC/DC) and Decision Coverage (DC)?	2002
CAST-11	Criteria for Assuring Complete Software Verification Processes Status: Superseded by CAST 11A	2002
CAST-11A	Criteria for Assuring Continuous and Complete Software Verification Processes	2007
CAST-12	Guidelines for Approving Source Code to Object Code Traceability	2002
CAST-13	Automatic Code Generation Tools Development Assurance	2002
CAST-14	Use of a Level D Commercial Off-the-Shelf Operating System in Systems with Other Software of Levels C and/or D Status: Cancelled	2002
CAST-15	Merging High-Level and Low-Level Requirements	2003
CAST-16	Databus Evaluation Criteria	2003
CAST-17	Structural Coverage of Object Code	2003
CAST-18	Reverse Engineering in Certification Projects	2003
CAST-19	Clarification of Structural Coverage Analyses of Data Coupling and Control Coupling	2004
CAST-20	Addressing Cache in Airborne Systems and Equipment	2003
CAST-21	Compiler-Supplied Libraries	2004
CAST-22	Reuse of Software Tool Qualification Data Across Company Boundaries (Applying the Reusable Software Component Concept to Tools)	2005
CAST-23	Software Part Numbering	2005
CAST-24	Reliance on Development Assurance Alone when Performing a Complex and Full-Time Critical Function	2006
CAST-25	Considerations When Using a Qualifiable Development Environment (QDE) in Certification Projects	2005
CAST-26	Verification Independence	2006
CAST-27	Clarifications on the use of RTCA Document DO-254 and EUROCAE Document ED-80, Design Assurance Guidance for Airborne Electronic Hardware	2006
CAST-28	Frequently Asked Questions (FAQs) on the use of RTCA Document DO-254 and EUROCAE Document ED-80, Design Assurance Guidance for Airborne Electronic Hardware	2006
CAST-29	Use of COTS Graphical Processors (CGP) in Airborne Display Systems	2007
CAST-30	Simple Electronic Hardware and RTCA Document DO-254 and EUROCAE Document ED-80, Design Assurance Guidance for Airborne Electronic Hardware	2007
CAST-31	Technical Clarifications Identified for RTCA DO-254 / EUROCAE ED-80	2012
CAST-32	Multi-core Processors Status: Superseded by CAST 32A	2014
CAST-32A	Multi-core Processors	2016
CAST-33	Compliance to RTCA DO-254/ EUROCAE ED-80, "Design Assurance Guidance for Airborne Electronic Hardware", for COTS Intellectual Property Used in Programmable Logic Devices and Application Specific Integrated Circuits	2014

Related Research Articles

DO-178B, Software Considerations in Airborne Systems and Equipment Certification is a guideline dealing with the safety of safety-critical software used in certain airborne systems. It was jointly developed by the safety-critical working group RTCA SC-167 of the Radio Technical Commission for Aeronautics (RTCA) and WG-12 of the European Organisation for Civil Aviation Equipment (EUROCAE). RTCA published the document as RTCA/DO-178B, while EUROCAE published the document as ED-12B. Although technically a guideline, it was a de facto standard for developing avionics software systems until it was replaced in 2012 by DO-178C.

A hazard analysis is used as the first step in a process used to assess risk. The result of a hazard analysis is the identification of different types of hazards. A hazard is a potential condition and exists or not. It may, in single existence or in combination with other hazards and conditions, become an actual Functional Failure or Accident (Mishap). The way this exactly happens in one particular sequence is called a scenario. This scenario has a probability of occurrence. Often a system has many potential failure scenarios. It also is assigned a classification, based on the worst case severity of the end condition. Risk is the combination of probability and severity. Preliminary risk levels can be provided in the hazard analysis. The validation, more precise prediction (verification) and acceptance of risk is determined in the risk assessment (analysis). The main goal of both is to provide the best selection of means of controlling or eliminating the risk. The term is used in several engineering specialties, including avionics, food safety, occupational safety and health, process safety, reliability engineering.

ARP4754, Aerospace Recommended Practice (ARP) ARP4754B, is a guideline from SAE International, dealing with the development processes which support certification of Aircraft systems, addressing "the complete aircraft development cycle, from systems requirements through systems verification." Revision A was released in December 2010. It was recognized by the FAA in AC 20-174 published November 2011. EUROCAE jointly issues the document as ED–79.

RTCA DO-254 / EUROCAE ED-80, Design Assurance Guidance for Airborne Electronic Hardware is a document providing guidance for the development of airborne electronic hardware, published by RTCA, Incorporated and EUROCAE. The DO-254/ED-80 standard was formally recognized by the FAA in 2005 via AC 20-152 as a means of compliance for the design assurance of electronic hardware in airborne systems. The guidance in this document is applicable, but not limited, to such electronic hardware items as

Integrated modular avionics (IMA) are real-time computer network airborne systems. This network consists of a number of computing modules capable of supporting numerous applications of differing criticality levels.

DO-160, Environmental Conditions and Test Procedures for Airborne Equipment is a standard for the environmental testing of avionics hardware. It is published by the Radio Technical Commission for Aeronautics (RTCA) and supersedes DO-138.

LDRA is a provider of software analysis, test, and requirements traceability tools for the Public and Private sectors. It is a pioneer in static and dynamic software analysis.

DO-178C, Software Considerations in Airborne Systems and Equipment Certification is the primary document by which the certification authorities such as FAA, EASA and Transport Canada approve all commercial software-based aerospace systems. The document is published by RTCA, Incorporated, in a joint effort with EUROC and replaces DO-178B. The new document is called DO-178C/ED-12C and was completed in November 2011 and approved by the RTCA in December 2011. It became available for sale and use in January 2012.

Advisory circular (AC) refers to a type of publication offered by the Federal Aviation Administration (FAA) to provide guidance for compliance with airworthiness regulations, pilot certification, operational standards, training standards, and any other rules within the 14 CFR Aeronautics and Space Title. They define acceptable means, but not the only means, of accomplishing or showing compliance with airworthiness regulations. Generally informative in nature, Advisory Circulars are neither binding nor regulatory; yet some have the effect of de facto standards or regulations.

AC 25.1309–1 is an FAA Advisory Circular (AC) that identifies acceptable means for showing compliance with the airworthiness requirements of § 25.1309 of the Federal Aviation Regulations. Revision A was released in 1988. In 2002, work was done on Revision B, but it was not formally released; the result is the Rulemaking Advisory Committee-recommended revision B-Arsenal Draft (2002). The Arsenal Draft is "considered to exist as a relatively mature draft". The FAA and EASA have subsequently accepted proposals by type certificate applicants to use the Arsenal Draft on development programs.

FAA Order 8130.34D, Airworthiness Certification of Unmanned Aircraft Systems, establishes procedures for issuing either special airworthiness certificates in the experimental category or special flight permits to unmanned aircraft systems (UAS), optionally piloted aircraft (OPA), and aircraft intended to be flown as either a UAS or an OPA.

The Advisory Circular AC 20-115( ), Airborne Software Development Assurance Using EUROCAE ED-12( ) and RTCA DO-178( ), identifies the RTCA published standard DO-178 as defining a suitable means for demonstrating compliance for the use of software within aircraft systems. The present revision D of the circular identifies ED-12/DO-178 Revision C as the active revision of that standard and particularly acknowledges the synchronization of ED-12 and DO-178 at that revision.

FAA Order 8110.105B, Airborne Electronic Hardware Approval Guidelines is an explanation of how Federal Aviation Administration (FAA) personnel can use and apply the publication

The Advisory Circular AC 20-152A, Development Assurance for Airborne Electronic Hardware, identifies the RTCA-published standard DO-254 as defining "an acceptable means, but not the only means" to secure FAA approval of complex custom micro-coded components within aircraft systems with Item Design Assurance Levels (IDAL) of A, B, or C. Specifically excluding COTS microcontrollers, complex custom micro-coded components include field programmable gate arrays (FPGA), programmable logic devices (PLD), and application-specific integrated circuits (ASIC), particularly in cases where correctness and safety can not be verified with testing alone, necessitating methodical design assurance.

DO-248C, Supporting Information for DO-178C and DO-278A, published by RTCA, Incorporated, is a collection of Frequently Asked Questions and Discussion Papers addressing applications of DO-178C and DO-278A in the safety assurance of software for aircraft and software for CNS/ATM systems, respectively. Like DO-178C and DO-278A, it is a joint RTCA undertaking with EUROCAE and the document is also published as ED-94C, Supporting Information for ED-12C and ED-109A. The publication does not provide any guidance additional to DO-178C or DO-278A; rather, it only provides clarification for the guidance established in those standards. The present revision is also expanded to include the "Rationale for DO-178C/DO-278A" section to document items that were considered when developing DO-178B and then DO-178C, DO-278A, and DO-330, as well as the supplements that accompany those publications.

CAST-32A, Multi-core Processors is a position paper, by the Certification Authorities Software Team (CAST). It is not official guidance, but is considered informational by certification authorities such as the FAA and EASA. A key point is that Multi-core processor "interference can affect execution timing behavior, including worst case execution time (WCET)."

DO-297, Integrated Modular Avionics (IMA) Development Guidance and Certification Considerations is one of the primary document by which certification authorities such as the FAA and EASA approve Integrated Modular Avionics (IMA) systems for flight. The FAA Advisory Circular (AC) 20-170 refers to DO-297.

The Advisory Circular AC 00-69, Best Practices for Airborne Software Development Assurance Using EUROCAE ED-12( ) and RTCA DO-178( ), initially issued in 2017, supports application of the active revisions of ED-12C/DO-178C and AC 20-115. The AC does not state FAA guidance, but rather provides information in the form of "best practices" complementary to the objectives of ED-12C/DO-178C.

CAST-31, Technical Clarifications Identified for RTCA DO-254 / EUROCAE ED-80 is a Certification Authorities Software Team (CAST) Position Paper. It is an FAA publication that "does not constitute official policy or guidance from any of the authorities", but is provided for educational and informational purposes only for applicants for software and hardware certification.

CAST-15, Merging High-Level and Low-Level Requirements is a Certification Authorities Software Team (CAST) Position Paper. It is an FAA publication that "does not constitute official policy or guidance from any of the authorities", but is provided to applicants for software and hardware certification for educational and informational purposes only.

References

1 2 3 Leanna Rierson (19 December 2017) [7 January 2013]. Developing Safety-Critical Software: A Practical Guide for Aviation Software and DO-178C Compliance. CRC Press. pp. 52–55. ISBN 9781351834056 . Retrieved 2022-03-03.
↑ Cary Spitzer; Uma Ferrell; Thomas Ferrell, eds. (2015). Digital Avionics Handbook, Avionics, Development and Implementation (3rd ed.). Boca Raton, FL: CRC Press. pp. 14–18. ISBN 978-1138076983. CAST was formed to promote harmonization of certification and regulatory positions on software and complex hardware aspects of safety.
↑ Rierson. p. 289-313.
↑ Cary Spitzer; Uma Ferrell; Thomas Ferrell, eds. (2015). Digital Avionics Handbook, Avionics, Development and Implementation (3rd ed.). Boca Raton, FL: CRC Press. pp. 14–18. ISBN 978-1138076983. CAST position papers are for education and information purposes and do not constitute official [FAA] policy or guidance.
1 2 "Certification Authorities Software Team (CAST)". Federal Aviation Administration. Retrieved 2021-10-29.
↑ "ANAC-EASA-FAA-TCCA Certification Management Team Collaboration Strategy" (PDF). Federal Aviation Administration. 2016. Retrieved 2021-10-29. The CMT should actively engage with industry and promote common solutions and approaches to aircraft certification within the international community.

External links

CAST Position Papers 1-31 at the Wayback Machine (archived 2013-05-27). Retrieved 2021-11-02.
CAST Position Papers 27-33 at the Wayback Machine (archived 2016-03-29). Retrieved 2022-08-19.
CAST Position Papers 27-33 with CAST-32A at the Wayback Machine (archived 2019-06-30). Retrieved 2022-08-19.

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[Rierson5255-1] 1 2 3 Leanna Rierson (19 December 2017) [7 January 2013]. Developing Safety-Critical Software: A Practical Guide for Aviation Software and DO-178C Compliance. CRC Press. pp. 52–55. ISBN 9781351834056 . Retrieved 2022-03-03.

[Spitzer2015a-2] Cary Spitzer; Uma Ferrell; Thomas Ferrell, eds. (2015). Digital Avionics Handbook, Avionics, Development and Implementation (3rd ed.). Boca Raton, FL: CRC Press. pp. 14–18. ISBN 978-1138076983. CAST was formed to promote harmonization of certification and regulatory positions on software and complex hardware aspects of safety.

[Rierson289-3] Rierson. p. 289-313.

[Spitzer2015b-4] Cary Spitzer; Uma Ferrell; Thomas Ferrell, eds. (2015). Digital Avionics Handbook, Avionics, Development and Implementation (3rd ed.). Boca Raton, FL: CRC Press. pp. 14–18. ISBN 978-1138076983. CAST position papers are for education and information purposes and do not constitute official [FAA] policy or guidance.

[FaaCast-5] 1 2 "Certification Authorities Software Team (CAST)". Federal Aviation Administration. Retrieved 2021-10-29.

[6] "ANAC-EASA-FAA-TCCA Certification Management Team Collaboration Strategy" (PDF). Federal Aviation Administration. 2016. Retrieved 2021-10-29. The CMT should actively engage with industry and promote common solutions and approaches to aircraft certification within the international community.

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