U.S. Department of Transportation Federal Aviation Administration
Subject: Airborne Software Assurance
Initiated by: AIR-120
AC No: 20-115C
1. Purpose of this Advisory Circular (AC).
a. This AC describes an acceptable means, but not the only means, for showing compliance
with the applicable airworthiness regulations for the software aspects of airborne systems and
equipment certification. This AC is not mandatory and is not a regulation. Other ACs may
describe alternate means.
b. We, the Federal Aviation Administration (FAA), wrote this AC to recognize the
following RTCA, Inc. documents (RTCA DO):
(1) RTCA DO-178C, Software Considerations in Airborne Systems and Equipment
Certification, dated December 13, 2011.
(2) RTCA DO-330, Software Tool Qualification Considerations, dated December 13,
(3) RTCA DO-331, Model-Based Development and Verification Supplement to DO-
178C and DO-278A, dated December 13, 2011.
(4) RTCA DO-332, Object-Oriented Technology and Related Techniques Supplement to
DO-178C and DO-278A, dated December 13, 2011.
(5) RTCA DO-333, Formal Methods Supplement to DO-178C and DO-278A, dated
December 13, 2011.
Note: RTCA DO is hereafter referred to as DO.
c. References to use of DO-178C in this AC include use of supplements and DO-330 as
d. This AC also establishes guidance for transitioning to DO-178C when making
modifications to software previously approved using DO-178, DO-178A, or DO-178B.
e. This AC also explains the use of DO-178C for Technical Standard Order (TSO)
f. This AC does not obligate the FAA to approve any data or perform any activities as
specified within the referenced RTCA documents.
g. If you use the means in this AC as a means of compliance, you must follow it entirely.