Tolerance for error
The design reduces dangers and the harmful effects of accidental or unintended actions.
Example
A power saw that needs the user to press two buttons at the same time before the blade turns on stops accidental starts and keeps safe users who may have trouble with hand movements or slower reactions.
Key point
Accepting some mistakes is not the same as stopping all mistakes. The principle says that mistakes should not cause serious harm. This is done by using warnings, safety features and designs that stop people from making accidental errors during important tasks.