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DO-178B, Software Considerations in Airborne Systems and Equipment Certification is a standard for software development. The standard was developed by RTCA and EUROCAE. The FAA accepts use of DO-178B as a means of certifying software in avionics.
Software level
The required level is determined from the safety assessment process and hazard analysis by examining the effects of a failure condition in the system. The failure conditions are categorized by their effects on the aircraft, crew, and passengers.
- Catastrophic - Failure may cause a crash.
- Hazardous - Failure has a large negative impact on safety or performance, or reduces the ability of the crew to operate the plane due to physical distress or a higher workload, or causes serious or fatal injuries among the passengers.
- Major - Failure is significant, but has a lesser impact that a Hazardous failure (for example, leads to passenger discomfort rather than injuries).
- Minor - Failure is noticeable, but has a lesser impact than a Major failure (for example, causing passenger inconvenience or a routine flight plan change)
- No Effect - Failure has no impact on safety, aircraft operation, or crew workload.
The number of objectives to be satisfied (with independence) is determined by the software level.
| Level | Failure condition | Objectives | With independence |
| A | Catastrophic | 66 | 25 |
| B | Hazardous | 65 | 14 |
| C | Major | 57 | 2 |
| D | Minor | 28 | 2 |
| E | No effect | 0 | 0 |
Processes and documents
The processes, activities and documents described here reflects naming and structure from DO-178B. This can be different in a real-life project.
Planning
Output documents from this process:- Plan for software aspects of certification (PSAC)
- Software development plan (SDP)
- Software verification plan (SVP)
- Software configuration management plan (SCMP)
- Software quality assurance plan (SQAP)
- System requirements
- Software requirements standard (SRS)
- Software design standard (SDS)
- Software code standard (SCS)
System requirements are typically input to the entire project.
The last 3 documents (standards) are not required for software level D.
Development
This process can be divided into sub-processes: requirements, design, code and integration.The development process output documents:
- Software requirements data (SRD)
- Software design description (SDD)
- Source code
- Executable object code
Traceability from system requirements to all source code or executable object code is typically required (depending on software level).
Typically used software development process:
Verification
Document outputs made by this process:- Software verification cases and procedures (SVCP)
- Software verification results (SVR):
- Review of all requirements, design and code
- Testing of executable object code
- Code coverage analysis
Analysis of all code and traceability from tests and results to all requirements is typically required (depending on software level).
This process typically also involves:
- Requirements based test tools
- Code coverage analyser tools
Other names for tests performed in this process can be:
- Unit testing
- Integration testing
- Black box and acceptance testing
Configuration management
Documents maintained by the configuration management process:- Software configuration index (SCI)
- Software life cycle environment configuration index (SECI)
This process handles problem reports, changes and related activities. The configuration management process typically provides archive and revision identification of:
- Source code development environment
- Other development environments (for e.g. test/analysis tools)
- Software integration tool
- All other documents, software and hardware
Quality assurance
Output documents from the quality assurance process:- Software quality assurance records (SQAR)
- Software conformity review (SCR)
- Software accomplishment summary (SAS)
This process performs reviews and audits to show compliance with DO-178B. The interface to the certification authority is also handled by the quality assurance process.
Certification liaison
- Typically a Designated Engineering Representative (DER) working for e.g. FAA in an airplane manufacturing company.
Certification in Europe
Tools
This part contains examples of software which can be used to automate, assist or otherwise handle or help in the DO-178B processes.
Requirements management
Development Environments
- SCADE and DO-178B Code Generator from Esterel Technologies
- SCORE from DDC-I
- Wind River Platform for Safety Critical DO-178B from Wind River Systems
- MULTI from Green Hills Software
Real-time operating systems and other commercial off the shelf software
- ''VAPS Qualifiable Code Generator (safety-critical embedded graphics tools) from Engenuity Technologies
- GL Studio® DO-178B (Graphics Display Development) from DiSTI
- INTEGRITY-178B RTOS from Green Hills Software
- LynxOS-178 from LynuxWorks
- QNX® Neutrino® RTOS from QNX Software Systems
Test, verification and analysis tools
- Cantata++ and AdaTEST from IPL
- CodeTest from Metrowerks
- Testbed from LDRA
- Test RealTime from Rational
- T-VEC from T-VEC Technologies
- VectorCAST from Vector Software
Configuration management
- A problem management tool can provide traceability for changes.
- SCI and SECI can be created from logs in a revision control tool.
Traceability tools
- Reqtify from TNI-Software
Resources
- FAR Part 23/25 §1301/§1309
- FAR Part 27/29
- AC 23/25.1309
- AC 20-115B
- RTCA DO-178B
- FAA Order 8110.49 Software Approval Guidelines
See also
- Avionics software
- ARP4761 (Safety assessment process)
- ARP4754 (System development process)
- DO-248B (Final Report for clarification of DO-178B)
- DO-254 (similar to DO-178B, but for hardware)
- Requirements Management (too general to be "directly applied" to DO-178B)
- IEC 61508
External links
Avionics | Safety | Embedded systems | Software development | RTCA standards
"DO-178B"