scope:

PURPOSE.

This notice provides guidelines to Aircraft Certification Service (AIR) field offices and to Designated Engineering Representatives (DER) regarding the application of RTCA DO-178B, "Software Considerations in Airborne Systems and Equipment Certification," to software for systems that were developed prior the issuance of Advisory Circular (AC) 20-115B, "Radio Technical Commission for Aeronautics, Inc. Document RTCA/DO-178B," on January 11, 1993. These systems are referred to as legacy systems throughout this notice and refer to systems developed under DO-178 or DO-178A. AC 20- 115B recognizes DO-178B as an acceptable means of compliance for the evaluation of software in airborne systems. DO-178B guidance for legacy systems is frequently misinterpreted and is not being consistently applied. This notice does not change the intent of DO-178B with regard to legacy systems but clarifies the application of DO-178B. Notice 8110.53, "Transition to RTCA/DO-178B, 'Software Considerations in Airborne Systems and Equipment Certification,'" was originally released to address this issue but did not meet all of the needs of the industry and certification authorities. This new notice should be used to apply DO-178B to legacy systems.