DO-178C Software in the Sky
An overview of DO-178C certification for airborne software: what it requires, why it matters, and how it shapes how we write code.
What is DO-178C?
DO-178C is the standard for developing airborne software. If your code runs on an aircraft, it must comply. There are no shortcuts.
Design Assurance Levels
| Level | Failure Condition | Example |
|---|---|---|
| A | Catastrophic | Flight control, autopilot |
| B | Hazardous | Engine control, navigation |
| C | Major | Fuel management, comms |
| D | Minor | Passenger entertainment |
| E | No effect | Maintenance logging |
What It Means in Practice
- 100% MC/DC coverage at Level A every boolean condition tested independently
- Traceability: Requirements → Design → Code → Tests (bidirectional)
- No dead code: Every line must be justified
- Formal reviews: Code reviews aren’t optional, they’re auditable artifacts
The Mindset Shift
In web dev, you ship fast and fix in production. In avionics, there is no “hotfix at 35,000 feet.” You prove correctness before the first flight.