Overview on DO-178B

What is DO-178B?
DO-178B/ED-12B provides guidance on designing, specifying, developing, testing and deploying software in safety-critical avionics systems. In sum DO-178B is a guideline for determining, in a consistent manner and with an acceptable level of confidence, that the software aspects of airborne systems and equipment comply with FAA airworthiness requirements.

Scope of DO-178B:
• Cover engineering process and some support process
• Does not cover organization, management, and customer-supplier relationship processes
• Life cycle data description.

DO-178B Levels:
DO-178B software levels (A, B, etc.) are based on the potential of the software to cause safety-related failures identified in the system safety assessment. DO-178B has five levels of certification:

1.Level A: Software whose failure would cause or contribute to a catastrophic failure of the aircraft. (e.g., aircraft crash).
2.Level B: Software whose failure would cause or contribute to a hazardous/severe failure condition. (e.g., several persons could be injured).
3.Level C: Software whose failure would cause or contribute to a major failure condition. (e.g., flight management system could be down, the pilot would have to do it manually).
4.Level D: Software whose failure would cause or contribute to a minor failure condition. (e.g., some pilot-ground communications could have to be done manually).
5.Level E: Software whose failure would have no effect on the aircraft or on pilot workload. (e.g., entertainment features may be down).

According to the DO-178B-level the following test coverage (code coverage) is required :
DO-178B Level A:
Modified Condition Decision Coverage (MC/DC)
Branch/Decision Coverage Statement Coverage
DO-178B Level B:
Branch/Decision Coverage
Statement Coverage
DO-178B Level C:
Statement Coverage


DO-178B Documents needed for Certification:(All items are not required at all certification levels.)
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)
Software Requirements Standards (SRS)
Software Design Standards (SDS)
Software Code Standards (SCS)
Software Requirements Data (SRD)
Software Design Description (SDD)
Software Verification Cases and Procedures (SVCP)
Software Life Cycle Environment Configuration Index (SECI)
Software Configuration Index (SCI)
Software Accomplishment Summary (SAS)





DO-178B Records for certification :


Software Verification Results (SVR)
Problem Reports
Software Configuration Management Records
Software Quality Assurance Records

For each software level, DO 178B identifies a specific set of objectives that must be satisfied:
Level A – 66 objectives
Level B – 65 objectives
Level C – 57 objectives
Level D – 28 objectives
Level E – none



Advantages of DO-178B:
By using the DO-178B or similar standards like ED-12B, organizations will have the
following advantages.
1. High degree of product focus leading to quality product.
2. Safety assessment of the product done in accordance with its role. The safety assess
ment is done at the beginning of the development cycle and based on the assess
ment the objectives for the level are complied with.
3. Very good verification & validation procedures to remove defects at each stage.
Procedures like MCDC test are done to remove all possible defects in the system.
4. Gives framework for development of safety critical systems
5. Makes sure that qualified tools and other COTS (Commercial Off The Shelf software)software are only used for critical systems by evaluating the procedure adopted in the development of such tools &COTS software.
6. Clear documentation that will facilitate certification and long product life cycles.


The software life cycle processes are:
1.PLANNING Process
The software planning process that defines and coordinates the activities of the software development and integral processes for a project.

2.DEVELOPMENT Process

The software development processes that produce the software product.
1.Software Requirements Process
2.Software Design Process
3.Software Coding ProcessIntegration process.

3.INTEGRAL Process

The Integral Processes that ensure the correctness, control, and confidence of the software life cycle processes and their outputs.
1.Software Verification Process
2.Software Configuration Management Process
3.Software Quality Assurance Process
4.Certification Liaison Process

Note: The integral processes are performed concurrently with the software development processes throughout the software life cycle.