Safety is a complex topic that is hard to precisely quantify. In terms of aircraft structural design,  Structural Safety relates to the failure of a component that results in an accident. This distinction between safety and structural safety is important, as many aspects that relate to the overall safety of an aircraft do not have anything to do with the structure it is comprised of.

Responsibility for safety in the aerospace industry is shared between three parties. First, the Airworthiness Authorities regulate safety by creating and monitoring compliance with safety regulations. Second, you have the Aircraft Manufacturers that have to design and fabricate aircraft which comply with the regulations. Third, you have the Aircraft Operators that maintain, inspect, and report on safety related issues. All three parties work together to ensure the high level of safety we enjoy today in air travel.