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OneNote/OSD/Safety/DO-254 Summary.md

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+**Simple and Complex hardware item:**
+
+_Something is simple if a comprehensive combination of deterministic tests and analyses ensures correct functional performance under all foreseeable operating conditions with no anomalous behavior._
+
+Everything else is a complex item.
+
+  
+
+- Simple hardware item: extensive documentation is unnecessary.
+- Complex items: design assurance should be agreed to by the certification authority.
+- Hierarchically analyse all levels for complexity. Include functions that are not testable such as unused modes or hidden states in sequential machines.
+
+# System Aspects of Hardware Design Assurance
+
+1. # System Aspects of Hardware Design Assurance
+    
+2. Allocate System functions to hardware (or software or combination of both)
+3. Assign system development assurance levels
+
+![FAR/JAR and Advisory Material 
+Systems 
+Safety 
+Assessment 
+Safety/ 
+Hardware 
+Hardware 
+Safety/ 
+Software 
+Safety/ 
+Hardware/ 
+Software 
+Software 
+Hardware 
+Software 
+Figure 2-1 Relationships Among Airborne Systems, Safety Assessment, 
+Hardware and Software Processes ](Exported%20image%2020231126172017-0.png)
+
+Overlaps are important: hardware function that contains safety requirements invokes safety assessment process and hardware design life cycle process.
+
+  
+
+- 3 Processes work in parallel:
+    
+    - System Development Process
+    - Hardware Design Life Cycle Process
+    - Software Life Cycle Process
+- Design assurance level: [defined](https://en.wikipedia.org/wiki/DO-178C) by impact on passenger safety.
+-   
+    
+- ![Level 
+    A 
+    B 
+    C 
+    D 
+    E 
+    Failure condition 
+    Catastrophic 
+    Hazardous 
+    Major 
+    Minor 
+    No Safety Effect 
+    [11] 
+    Objectives 
+    71 
+    69 
+    62 
+    26 
+    With independence 
+    30 
+    18 
+    5 
+    2 ](Exported%20image%2020231126172017-1.png)
+- Objective with independance: another person must verify the item.
+
+  
+
+Questions
+
+- [ ] What is our software assurance process
+
+Todo:
+
+- [ ] Define functions with associated requirements,  
+failure conditions and design assurance level
+
+Review:
+
+- [ ] Chap2