Problem: Many military aviation systems have a civil heritage with software developed using the civil aviation guidelines, DO-178B. Furthermore, major suppliers developing systems for both civil and military aircraft are basing their software development processes on the DO-178B guidelines. Consequently, the MoD is increasingly being offered COTS systems (or COTS with minor modifications) with software developed to DO-178B.

For bespoke systems, the release of Def Stan 00-56 issue 3 (and the change of Def Stan 00-55 issue 2 to "obsolescent" status) has left procurers and developers with no detailed guidance as to how software should be developed safely. There are proposed software guidance annexes to Def Stan 00-56 issue 3 due in the autumn. Nevertheless, aviation developers would like to use or adapt DO-178B to provide design assurance of software within the context of a safety programme following Def Stan 00-56 issue 3. The MoD is increasingly being asked by suppliers to consider new systems for procurement containing software that is proposed for development using the DO-178B guidelines.

Challenge: The challenge for the MoD is to provide a mechanism for the acceptance of systems for both previously developed systems (where the software has been developed to DO-178B) and bespoke systems (where the software is to be developed to DO-178B). The use of DO-178B may not be the optimal approach (as considered by the MoD) but, in principle, its use can be accommodated within a safety programme compliant with Def Stan 00-56 issue 3 .

As regards bespoke software, it is essential that a DO-178B development is afforded the oversight required to ensure that sufficient design assurance is demonstrated to meet the safety integrity requirements derived from Def Stan 00-56. DO-178B has been designed for the applicant (i.e. the developer) to produce appropriate outputs that meet the objectives of RTCA DO 178B. The outputs are presented for Certification Approval from a national body such as the CAA, FAA, and EASA.

With regard to a military procurement the MoD, with initial delegation to the IPTs, is responsible for providing comparable oversight or subcontracting oversight to an approved Competent Authority.

Solution: ASSC Guidance on DO-178B Development:
The ASSC has produced a guidance document for IPTs to facilitate the acceptance of systems containing software previously developed to DO-178B and/or software proposed for development using DO-178B.

For bespoke software, the guidance is written using process flow charts and checklists to describe the oversight required by the IPTs at each of the software lifecycle stages, that is planning, requirements, design, detailed design and coding, and various levels of integration.

For both bespoke and previously developed software (including COTS), the guidance includes the allocation of software design assurance levels (Software Levels) and the evidence required for the incorporation of COTS software.

ERA now runs courses regarding DO-178B, to find out more click the link >>>

For further information please e-mail: assc@era.co.uk or call: +44 (0) 1372 367141