1. LDRA Technology Pvt. Ltd
Software Technology
A Practitioner's Guide to DO-178B, Certification and the Emerging DO-178C Standard
Shinto Joseph
Operations Director,
LDRA Technology Pvt. Ltd
Bangalore 1

2. Verification Activities
Agenda
Introduction
DO-178B Overview
Verification Activities
Review
Testing
Analysis
What’s Coming with DO-178C?
DO-178C Structure
Software Development Landscape
Traceability
Indian Scenario
Summary 2

3. Agenda
DO-178B Overview

4. DO-178’s Timeline DO-178, November 1981 DO-178A, March 1985
Basic guidance
DO-178A, March 1985
3 failure conditions / software levels
critical/1, essential/2, non-essential/3
Development/verification steps
DO-178B, December 1992
5 failure conditions / software levels
Catastrophic/A, Hazardous/B, Major/C, Minor/D, no effect/E
Objectives-based
DO-178C, 2011?
A modest update to DO-178B (If C based development)
Adds guidance on model-based development,
formal methods, object-oriented technology & tool qualification

5. F-16 Falcon
Unstable airframe

6. F-16 Falcon
Unstable airframe
Flipped crossing 0o

7. ? What failures can occur Severity Probability Hazard Analysis
Result - System level Safety Integrity Level (SIL)

8. Probability of Failure
DO-178B Safety Integrity Levels
Software Level
Impact
of Failure
Probability of Failure
(per operating hour)* A
Catastrophic
10-9 B
Hazardous
10-7 C
Major
10-5 D
Minor
10-3 E
No effect
N/A
*FAA System Safety Handbook, Chapter 3: Principles of System Safety; December 30, 2000

9. DO-178B process
Safety Assessment Process Guidelines & Methods (ARP 4761)
Intended
Aircraft
Functions
Safety Information
System Design Information
Aircraft and System Development Processes
(ARP 4754)
Guidance for Integrated Modular Avionics (DO-297)
Electronics Hardware Development Lifecycle (DO-254)
Electronics Hardware Development Lifecycle (DO-254)
Electronics Hardware Development Lifecycle (DO-254)
Software Development Lifecycle (DO-178B)

10. …..DO-178B process
Intended to ensure that avionics software performs its
intended function with an appropriate level of confidence in
safety.
Defines 5 processes:
Planning, development, verification, configuration management and quality assurance
Defines 5 levels of design assurance and 66 objectives:
Level A: 66 objectives (25 with independence)
Level B: 65 objectives (14 with independence)
Level C: 57 objectives
Level D: 28 objectives
Level E: no objectives
Provides guidelines for implementing these processes
and meeting these objectives. 10

11. Structural Coverage Technique
DO-178B (cont.)
Certifiable Software became central goal
Deterministic Verification Techniques
Software Level
Impact
of Failure
Structural Coverage Technique A
Catastrophic
MC/DC B
Hazardous
Decision C
Major
Statement
MC/DC code coverage ensures that all conditions
that independently affect a programmatic result have
been tested

12. Verification Process
Purpose: Detect and report errors that have been introduced during the software development process.
Objectives:
System
Requirements
satisfies
Software
Requirements
satisfies
Software
Architecture
satisfies
satisfies
satisfies
Executable
Object Code
Source
Code 12

13. Verification Activities
Review
A qualitative assessment of accuracy, completeness consistency and correctness.
Testing
Demonstrate that the software satisfies its requirements.
Demonstrate, to an appropriate degree of confidence, that errors that could lead to unacceptable failure conditions have been removed.
Analysis
A quantitative assessment of accuracy, completeness consistency and correctness. 13

14. Review
A review provides a qualitative assessment of accuracy, completeness consistency and correctness.
IP boilerplate
Comments
Indentation
Complexity …
- Compliance with requirements
Compliance with architecture
Verifiability
Accuracy and consistency …
standards
checklist
if (x < 0) then
z = y – 2;
else
z = y + 2;
Review
Result
source
code 14

15. Testing
Testing demonstrates, to an appropriate degree of confidence, that software satisfies its requirements and that errors that could lead to unacceptable failure conditions have been removed.
Requirements-based tests: verify implementation of requirements.
HW/SW integration tests: verify correct operation in the target computer environment.
SW/SW integration tests: verify software interfaces and interrelationships. 15

16. Test success Test failure Test Result Analysis Proceed
Incorrect software behavior
Incorrect requirement
Incorrect test case/procedure
Incorrect test environment/setup 16

17. Traceability Analysis
Requirements
Code
Tests
Objectives
Verify that every requirement is implemented.
Verify that every requirement is tested.
Verify that every line of code has “a reason to be”.
Common gaps
Requirement has no associated tests:
Missing trace information, missing tests.
Requirement has no associated source code:
Missing trace information, missing code, extraneous requirement.
Source code doesn’t trace to requirements:
Missing trace information, extraneous code. 17

18. Moving from DO-178B to C: The Essentials18

19. DO-178C
Core Document
Including DO-178B &
Revised Processes

20. Core Document DO-178C Including DO-178B & Revised Processes Formal
Methods
Supplement
Model-Based
Development
Supplement
Object-
Oriented
Technologies
Supplement

21. Core Document DO-178C Including DO-178B & Revised Processes
Formal
Methods
Supplement
Model-Based
Development
Supplement
Object-
Oriented
Technologies
Supplement
Tools Supplement

22. Software Development Landscape
DO-178C
Software Development Landscape

23. High Level
Requirements
Tier 1

24. High Level Requirements Modelling Tools Formal Methods Software Specs
Tier 1
Modelling Tools
Formal Methods
Software Specs
Hand Code
Tier 2

25. (Source Code / Assembly )
High Level
Requirements
Tier 1
Modelling Tools
Formal Methods
Software Specs
Hand Code
Tier 2
Implementation
(Source Code / Assembly )
Tier 3

26. (Source Code / Assembly )
High Level
Requirements
Tier 1
Modelling Tools
Formal Methods
Software Specs
Hand Code
Tier 2
Implementation
(Source Code / Assembly )
Tier 3
Host Tier
(Node 1 – n)
Tier 4

27. (Source Code / Assembly )
High Level
Requirements
Tier 1
Modelling Tools
Formal Methods
Software Specs
Hand Code
Tier 2
Implementation
(Source Code / Assembly )
Tier 3
Host Tier
(Node 1 – n)
Tier 4
Target Tier
(Node 1 – n)
Tier 5

28. Requirements Traceability Matrix
High Level
Requirements
Tier 1
Requirements Traceability Matrix
Design
Review
defects
LL Reqs
to HL Reqs
Modelling Tools
Formal Methods
Software Specs
Hand Code
Tier 2
Requirements Traceability Matrix
Code &
Quality
Review
defects
Code to
LL Reqs
Implementation
(Source Code / Assembly )
Tier 3
Test Results
& Defects
Requirements Traceability Matrix
Test Cases
to LL Reqs
Host Tier
(Node 1 – n)
Tier 4
Test Results
& Defects
Requirements Traceability Matrix
Test Cases
to LL Reqs
Target Tier
(Node 1 – n)
Tier 5

29. Traceability:
Complex

30. Low Level Requirements, or design?
Complexity: Sources
Formal
Methods
Model-Based
Development
Object-
Oriented
Technologies
Low Level Requirements,
or design?
Dynamic aspects:
Coverage must be performed on target
& combined with static traces to assure completeness

31. DO-178C Traces Level A, B,C and D
System requirements allocated to Software
High-Level Requirements
Test Cases
Low-Level Requirements
Test Procedures
Review and
Analysis Results
Source Code
Test Results
Executable Object Code
SW Architecture

32. DO-178C Traces Level A, B,C and D
System requirements allocated to Software
Level A, B and C
High-Level Requirements
Test Cases
Low-Level Requirements
Test Procedures
Review and
Analysis Results
Source Code
Test Results
Executable Object Code
SW Architecture

33. DO-178C Traces Level A, B,C and D
System requirements allocated to Software
Level A, B and C
Level A
High-Level Requirements
Test Cases
Low-Level Requirements
Test Procedures
Review and
Analysis Results
Source Code
Test Results
Executable Object Code
SW Architecture

34. Requirements Traceability Matrix
IBM® Rational® DOORS®
& Visure IRQA...
High Level
Requirements
TBreq®
Requirements
Traceability
TBmanager®
System Test
Management
Unit Test
Requirements Traceability Matrix
LDRA Testbed®
Design Review
Defects
Modelling Tools
Formal Methods
Software Specs
Hand Code
Requirements Traceability Matrix
TBvision®
Code Review
Defects
Implementation
(Source Code / Assembly)
Requirements Traceability Matrix
TBrun®
Host
Testing
Host Tier
(Node 1 – n)
Requirements Traceability Matrix
TBrun®
Target
Testing
Target Tier
(Node 1 – n)

35. -Lack of safety awareness -Gap between local and global practices
Indian Scenario
-Lack of safety awareness
-Gap between local and global practices
-Sudden demand for aerospace skills
-Need for a healthy ecosystem, backed by
long term govt. policies
-Committed engineers ready to work on
Indian projects
-Role of technology vendors
-Regulatory framework- Defense and Civilian

36. Verification is an important component of DO-178
Summary
Summary
Verification is an important component of DO-178
Review
Testing
Analysis
Bottom line
Detect and report errors that have been introduced during the software development process.
Ensure that the software performs its intended function to an appropriate degree of confidence. 36

37. Future: ......Summary …Requirements management / traceability
paradigm no longer adequate
Future:
Should accommodate emerging technologies, methodologies
Requires distributed, collaborative, bidirectional traceability mechanism
Security
India- an aerospace powerhouse…..

38. Copyright © 2011 Liverpool Data Research Associates Limited
Software Technology
Thank you for your time today. If you require any further information please visit the LDRA website, or me direct with any questions you may have.
Copyright © 2011 Liverpool Data Research Associates Limited 38