Safety: Part 2 - Development Assurance and Design Assurance

The Development Assurance and the Design Assurance are the terms generally used in the Avionic sector.

These terms are identified and defined in international guidelines such as EUROCA ED-79A/SAE ARP-4754A and EUROCAE ED-80/RTCA DO-254.

The Development Assurance and the Design Assurance consist on the complete set of systematic and planned actions used to substantiate, at an adequate level of confidence, that errors in requirement, design and implementation have been identified and corrected such that the system, equipment or item satisfies the applicable Certification Basis.

This means that during the planning activities it shall be necessary to identify and plan all actions that shall be performed during the development activities in order to guarantee the adequate level of confidence necessary.

The level of confidence requested during the development of a System, Equipment or Item is not the same, but it depends on the type of function implemented and the relevant effect that a failure can generate at aircraft level.

The Design Assurance Level or the Development Assurance Level (DAL) is used to identify the level of confidence necessary to establish the level of confidence necessary.

The term DAL is used in general to specify the Design Assurance Level, while the F-DAL is used to specify the Functional Design Assurance Level and the I-DAL is used to identify the Item Design Assurance Level.

In general the Design Assurance Level identified by the rules and international guidelines are defined as follow:

• Level A: It is the highest level of Design Assurance applicable to an Equipment / Airborne Electronic Hardware / Avionic Software. It will be assigned when the potential failure or malfunction could contribute to a Catastrophic failure at aircraft level.
• Level B: It will be assigned when the potential failure or malfunction could contribute to an Hazardous failure at aircraft level.
• Level C: It will be assigned when the potential failure or malfunction could contribute to a Major failure at aircraft level.
• Level D: It will be assigned when the potential failure or malfunction could contribute to a Minor failure at aircraft level.
• Level E: it will be assigned when the potential failure or malfunction does not have any safety effect at aircraft level.