At the same time software in the air needs to be certified in order to guarantee safety. The DO-178 series is the reference for any flying software. In november 2011 the DO-178C has been approved by RTCA/EUROCAE joint committee gathering certification authorities and the avionic industry. It introduces two new complementary documents regarding the Model based Development and Verification (MBDV) in DO-331, and the Software Tool Qualification Consideration in DO-330.
|DO178C software levels||Effect of software malfunction|
|Level A||Failure may cause multiple fatalities|
|Level B||Failure has a large negative impact on safety or performance|
|Level C||Failure significantly reduces the safety margin|
|Level D||Failure slightly reduces the safety margin|
|Level E||Failure has no impact on safety|
Chapter 23 of EASA Certification Memorandum on Software Aspects of Certification by European Aviation Safety Agency, 11 August 2011 regarding the validation and verification of model based software requirements and designs namely quotes SDL (LDS in the text) as a modeling technology to design embedded software of aircraft equipment as well as Scade, Matlab and SAO.
PragmaDev Studio is perfect to model communicating avionic systems and even though PragmaDev Studio code generator is not qualified, our customers in the aeronautics did certify their model and the code generated out of the model.
It is also a domain where several levels of sub-contractors from large key accounts to small SMEs work together. Communication between the different stakeholders is paramount since a slight misunderstanding might end up in a financial disaster.
Modeling is a well proven mean of communication. The more precise the model is, the less chance there is to misunderstand the needs. Because of the high degree of telecommunication in military systems an event driven approach is more suitable than any other. Not only the static interfaces should be adressed, but more importantly the sequence of events between the different equipments.
Because of the above PragmaDev Studio event driven executable modeling technology is a perfect match for defense systems and equipments.
Requirements engineering is currently identified as one of the weak points of the software development lifecycle. Many space project reviews identify weakness in the software requirements in the early development. This leads to an incomplete development, followed by difficulties in system integration and costly software reengineering.
The importance of having consolidated software requirements at avionics level [Requirement Baseline] makes desirable the use of modellisation techniques that help the specifiers to achieve complete and consistent requirements. At software level [Technical Specification], the modellisation assists with the verification of the requirements and, more and more, with the code design and generation.
The modellisation covers:
For the above reasons ESA has defined the TASTE framework, an open source tool for embedded software development. The main idea is to use the most appropriate language out of a selected list of mature and existing ones. The framework will then generate the glue between the different parts of the model. Some of the selected technologies are: