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Can the real time operating system used in aviation equipment be certified by itself, or must it be a part of some software certification effort?

I'm asking for getting a certificate of 178C. I don't understand if it is possible. There are a lot of resources that tell us about "certified operating system", but if is certified as a part of a project or it is certified just itself without any project... I have no practise in this field, but I was asked this question and it makes me puzzled.

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A DO-178C compliant RTOS (such as LynxOS-178 mentioned by @mins) is going to have a certification package you provide along with your DO-178C artifacts for your software.

Note that there is no such thing as a DO-178C "certificate". DO-178C is a process that generates certification artifacts that are packaged and provided to the Certification Authority as part of some approval application (TSO, TC, STC, PMA)

It is also usefull to recognize that most software on equipment installed on an aircraft is not going to run on an RTOS, but rather run directly on the hardware (bare metal)

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  • $\begingroup$ So the RTOS is certificated as part of a larger system. I would also say that almost every avionics product I've worked on in the last 20+ years had an RTOS of some type. Some were pretty small purpose-built OSes, but it's important to have an OS to provide an abstraction layer from the hardware. Writing directly to the HW will cause major rework when the HW go obsolete - and it will. The only ones I can think of without an OS were simple controllers that were based on Programmable Interface Controllers (PIC). $\endgroup$
    – Gerry
    Feb 14, 2019 at 1:43
  • $\begingroup$ IMA systems would likely use an RTOS to host various tasks/applications, which I haven't worked on. Everything else I've worked on have been custom PCBs with a microcontroller or microprocessor and custom software. An RTOS is either very expensive, difficult to certify, or entirely unnecessary for the product at hand. $\endgroup$
    – selectstriker2
    Feb 14, 2019 at 1:55
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    $\begingroup$ IMA systems require a DAL Level A RTOS as all applications on the IMA have to operate in their own protected partitions. They are complex and expensive. But even for simpler federated products we often used LynxOS or a simple custom RTOS. The reason was to provide a standard programming API to simplify the application software and resulting changes needed when the inevitable hardware changes came along. I will agree that for some products it wouldn't make sense to go through the effort to use an RTOS. $\endgroup$
    – Gerry
    Feb 14, 2019 at 3:37
  • $\begingroup$ I could see the likelyhood of using an RTOS on new projects increasing once a company has invested either in purchasing the cert artifacts for one or developing their own. $\endgroup$
    – selectstriker2
    Feb 14, 2019 at 14:48

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