ARINC 645 PDF

This specification focuses on loadable data and software, primarily Aircraft Controlled Software (ACS). This software is controlled at an aircraft level, meaning the software is treated as an aircraft part – Loadable Software Aircraft Part (LSAP). The software does not affect the part number of the physical hardware in which it is loaded. For more information about ACS, reference ARINC Report 667: Guidance for the Management of Field Loadable Software.

Conversely, software that is not controlled as an aircraft part is Hardware Controlled Software (HCS). This software, when loaded into an instance of aircraft equipment, changes the effectivity and part number of the physical hardware. For more information about HCS, reference ARINC Report 849: Data Loading Specification for Avionics Components.