d. RTCA, Inc. Documents. You may buy copies of RTCA documents from RTCA, Inc., 1828 L Street, NW, Suite 805, Washington, D.C. 20036. Alternatively, you may buy copies online at http://www.rtca.org/. RTCA documents relevant to this AC are:
(1) RTCA, Inc., Document RTCA/DO-178B, Software Considerations in Airborne Systems and Equipment Certification, dated December 1, 1992.
(2) RTCA, Inc., Document RTCA/DO-248B, Final Report for Clarification of DO-178B Software Considerations in Airborne Systems and Equipment Certification, dated October 12, 2001.
e. Society of Automotive Engineers (SAE) Documents. You may buy copies of SAE Aerospace Recommended Practices (ARP) from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. Or, you may buy copies on-line at http://www.sae.org/. The following SAE ARPs are relevant to this AC:
(1) ARP4754, Certification Considerations for Highly-Integrated or Complex Aircraft Systems.
(2) ARP4761, Guidelines and Methods for Conducting the Safety Assessment Process on Civil Airborne Systems and Equipment.
Susan J.M. Cabler Acting Manager, Aircraft Engineering Division Aircraft Certification Service Page 23 (and 24)
Appendix 1 APPENDIX 1. DEFINITIONS OF TERMS The RTCA/DO-178B Annex B definitions and the following definitions apply to this AC:
a. Acceptance is credit the FAA grants for fully or partially meeting RTCA/DO-178B objectives for an RSC. The FAA shows acceptance by issuing an RSC acceptance letter.
b. Access mechanism is the manner in which a software component performs its intended function. This includes invocation mechanisms and data flow to and from the component. This is typically part of the interface description data.
c. Applicant is the manufacturer seeking certification of the product or authorization of the equipment. The applicant may be applying for a TC, STC, ATC, ASTC, or TSO authorization.
d. Certification authority is the organization or person in the state or country, who certifies compliance with the requirements. The certification authority is typically the FAA or foreign certification authority engineer.
e. Credit is compliance to one or more RTCA/DO-178B objectives supported by RTCA/DO-178B software life cycle data. This compliance shows the equipment meets the certification basis and may receive a certificate. This AC refers to three types of credit:
(1) Full credit – fully meets the RTCA/DO-178B objective and requires no further activity by the applicant or integrator.
(2) Partial credit – partially meets the RTCA/DO-178B objective and requires more activity by the applicant or integrator to complete compliance.
(3) No credit – does not meet the RTCA/DO-178B objective, and the applicant or integrator must complete the objectives for compliance.
f. Designee is a person authorized to make compliance findings on the FAA’s behalf for the specific project.
g. First use of RSC is the first acceptance of an RSC in a certification project.
h. In-service experience is experience gained while using the RSC in a certificated aircraft or engine.
i. In-service problem report is the documentation of a problem or difficulty discovered during an in-service experience.
j. Integrator is the manufacturer, who integrates the RSC into the target computer and system with other software components.
k. Interface description data identify the interface details of the RSC. The RSC developer gives the data to the integrator or applicant. The interface description data should Page A1-1
Appendix 1 clearly define what the integrator or applicant must do to ensure the RSC will perform per its approval basis.
l. Maintenance code is code in an airborne computer-based system that interfaces with an onboard maintenance computer or computer used by maintenance personnel. This code usually reports to the maintenance computer any problems detected during normal operations.
m. Reusable software component (RSC) is the software, its supporting RTCA/DO-178B software life cycle data, and other supporting documentation being considered for reuse. The component designated for reuse may be any collection of software, such as libraries, operating systems, or specific system software functions.
n. RSC developer is the manufacturer of the RSC.
o. RSC user is an integrator or applicant who uses the RSC.
p. Settable parameters are software component data that are set before execution of the component.
q. Softw are characteristics include the Executable Object Code size, timing and memory margins, resource limitations, and the means of measuring each characteristic (see Section 11.20(d) of RTCA/DO-178B).
r. Softw are component is some part of the airborne system’s software. It usually performs a specific function in the system.
s. Software life cycle data are data produced during the software life cycle to plan, direct, explain, define, record, or provide evidence of successful completion of activities (see RTCA/DO-178B, Section 11.0). Sections 11.1 through 11.20 of RTCA/DO-178B describe different kinds of software life cycle data.
t. Stakeholders are all the persons and groups involved in the development, integration, and acceptance of the RSC. Stakeholders in this AC are the RSC developer, integrator, applicant, and certification authority. One or more manufacturers may assume the roles of the RSC developer, integrator, and applicant.
u. Subsequent use of RSC is the follow-on use of an accepted RSC. That is, it is not the first use of the RSC.
v. Target computer is the physical processor that will execute the program while airborne.
w. Target computer environment is the target computer and all its support hardware and systems needed to function in its airborne environment.
x. Target environment is the same as target computer environment (above).
y. User – see “RSC user” above.
Page A1-2
Appendix 1
z. Variables are memory locations that contain data that will change during software execution.
Page A1-3 (and A1-4)
Appendix 2
APPENDIX 2. ACRONYMS The following acronyms are used in this AC:
AC Advisory Circular AD Airworthiness Directive ARP Aerospace Recommended Practice ASTC Amended Supplemental Type Certificate ATC Amended Type Certificate CFR Code of Federal Regulations CMR Certification Maintenance Requirement CSTA Chief Scientific and Technical Advisor FAA Federal Aviation Administration PSAC Plan For Software Aspects Of Certification RSC Reusable Software Component SAE Society of Automotive Engineers SAS Software Accomplishment Summary SCI Software Configuration Index SCMP Software Configuration Management Plan SDP Software Development Plan SQAP Software Quality Assurance Plan STC Supplemental Type Certificate SVP Software Verification Plan TC Type Certificate TSO Technical Standard Order Page A2-1 (and A2-2)
AC 20-148 Appendix 3 APPENDIX 3. SAMPLE FORMAT FOR RSC DEVELOPER'S TABLE Activities Remaining For Integrator or Applicant Note 4 Note 4 Note 4 NOTE 4: List the activities remaining for the integrator or applicant to complete the objective. This should be in enough detail that the integrator or applicant and the certification authority can clearly understand what remains for the overall acceptance of the system Means of Compliance for the Objective Note 3 Note 3 Note 3 Note 3 Note 3 NOTE 1: Include if seeking FULL, PARTIAL, or NO credit for the RSC. See Section 5d(1) of this AC. NOTE 3: List data that documents the compliance to this objective. See Section 5d(3) of this AC.
Assumption Note 2 Note 2 Note 2 Note 2 Note 2 NOTE 2: List all assumptions made for the credit claim. See Section 5d(2) of this AC.
Credit Sought Note 1 Note 1 Note 1 Note 1 Note 1 Objective Description Software development and integral processes activities are defined. Transition criteria, inter- relationships and sequencing among processes are defined Software life cycle environment is defined. Additional considerations are addressed Software development standards are defined. using the RSC. See Section 5d(4) of this AC.
DO-178B Obj # 1-1 1-2 1-3 1-4 1-5 and so on Page A3-1 (and A3-2)