Editing Avionics software (section)

===Hazard analysis===
Safety-critical avionics usually have a [[hazard analysis]].  The early stages of the project, already have at least a vague idea of the main parts of the project.  An engineer then takes each block of a block diagram and considers the things that could go wrong with that block, and how they affect the system as a whole.  Subsequently, the severity and probability of the hazards are estimated.  The problems then become requirements that feed into the design's specifications.

Projects involving military cryptographic security usually include a security analysis, using methods very like the hazard analysis.