Functional Allocation
Section 11: Aircraft & Avionics Architecture
Definition
The process of assigning aircraft-level functions to specific systems, and subsequently allocating system functions to hardware items and software components within the system architecture. Functional allocation establishes which physical elements implement each required function and defines the interfaces between them.
Where This Shows Up
Functional allocation is a key step in the ARP 4754A system development process and has direct implications for certification. The allocation determines which equipment items are safety-relevant and at what DAL they must be developed. It also defines the failure modes that must be considered in the system safety assessment: a function allocated across multiple items must address the common-cause failure potential, while a function implemented in a single item must address all single-point failures. The functional allocation is documented in system-level requirements and architecture documents and feeds directly into the item definition process for hardware (DO-254) and software (DO-178C) development.
Primary Sources
Sections 5.2 and 5.3 — describe the functional allocation process as part of the system development lifecycle.
Related Terms
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