I would like to understand the design philosophies of aviation embedded systems that provide real time control and instrumentation like EICAS/FMS/GPWS & TCAS.

  1. What kind of embedded OS platforms do they use? VxWorks Linux, RT Linux

  2. Is there a specific design philosophy in Computer Science that is used for ensuring real time behavior? (Just like fault tolerant hardware for fail proofing?)

  • $\begingroup$ Hi and welcome! Please consider whether question might be better suited for the Computer Science SE or a similar one. While related to aviation, the gist is about software architecture, which is not the main topic here. $\endgroup$ – AEhere supports Monica Jul 29 '19 at 21:19
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    $\begingroup$ Possible duplicate of What type of computers are in a flight system? $\endgroup$ – Gerry Jul 29 '19 at 21:30
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    $\begingroup$ Voting to leave open. It is a question about the specifics of aviation related computer systems, which differ from your generic Windows desktop. Question 2. makes it not a duplicate. $\endgroup$ – Koyovis Jul 29 '19 at 22:00
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    $\begingroup$ I think this question is about aviation and deserves to remain. It’s not just about piloting. Otherwise things like N1/N2 blades, drags, VOR frequencies etc... all become technical quickly and automatically disqualified $\endgroup$ – Ace Jul 29 '19 at 22:11

There are various standards out there and ways of doing things but DO-178C is the latest iteration of the document that outlines how real time avionics are to be programed. Certifying agencies like the FAA may have their own supplements/orders that specify specifics for a given jurisdiction, for example here is the FAA's order.

Avionics themselves often connect over the ARNIC data bus.

Many avionics and aircraft companies design their own OS's when they needed them for real time applications

Honeywell, for example, created the digital "engine" operating system (DEOS) and Rockwell Collins, the virtual machine operating system (VMOS), which it engineered from an earlier LynuxWorks product in the late 1990s. Collins licensed the changes back to LynuxWorks in the 2002-2003 time frame, and LynuxWorks now offers the new version of the software as LynxOS-178.

WindRiver did the OS for the dreamliner

Smiths Aerospace chose Wind River Systems' VxWorks 653 RTOS for the B787's common core system (CCS), a cabinet that will host 80 to 100 applications, including Honeywell's FMS and health management software and Collins' crew alerting and display management software.

There is a great podcast on designing spacecraft software (basically the same use case) that you can find here.

Its worth noting that the cost to certify avionics tends to be quite high (under the FAA) so code and methodology dont change all to much. Once avionics get certified companies have a way of continuing to make them for a very, very, very long time.


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