The Advisory Circular AC 20-115( ), Airborne Software Development Assurance Using EUROCAE and RTCA (previously Airborne Software Assurance), recognizes the RTCA published standard DO-178 as defining a suitable means for demonstrating compliance with applicable airworthiness regulations for the use of software within aircraft systems. The present revision D of the circular identifies ED-12/DO-178 Revision C as the active revision of that standard and particularly acknowledges the synchronization of ED-12 and DO-178 at that revision.
This Advisory Circular calls attention to ED-12C/DO-178C as "an acceptable means, but not the only means," to secure FAA approval of software. The earliest revisions of the Advisory Circular were brief, serving little more than to call attention to active DO-178 revisions. The Advisory Circular revisions C and D are considerably longer, giving guidance in modifying and re-using software previously approved using DO-178, DO-178A, or DO-178B (preceding revisions of the DO-178 standard). Additionally, the expanded AC now provides guidance for Field Loadable Software and User Modifiable Software within aircraft software. Transition of legacy tool qualification from DO-178B to DO-330 is also discussed, with comparison of ED-12B/DO-178B Tool Qualification Type with ED-12C/ED-215 DO-178C/DO-330 Tool Qualification Level.
Simultaneously with the publication of FAA AC 20-115D, EASA issued AMC 20-115D. This EASA Acceptable Means of Compliance (AMC) publication resulted from 2 years of coordinate effort with the FAA on AMC 20-115D to improve harmonization and mutual recognition between the civil aviation authorities. AMC 20-115D and AC 20-115D are technically identical. However, there are some wording differences.